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Gravitational-wave detection provides humanity with unique access to extreme astrophysical and cosmological phenomena. In space-based missions, however, the Doppler frequency pulling induced by orbital motion severely limits the precise extraction of gravitational-wave signals. This work shows that by introducing properly designed low-pass filters into established laser arm-locking systems, it is possible to maintain a high suppression ratio of laser frequency noise while drastically reducing Doppler pulling. Moreover, with the proposed scheme, the arm-locking system can precisely predict the Doppler frequency without the need to know the real-time distance between satellites, thereby greatly simplifying the complexity of hardware implementation. These results can be generalized and applied to other arm-locking configurations operating in more complex multi-perturbation environments.

Classical gravitational waves (GWs) are stable in vacuum. We show that treated as coherent graviton states, they decay into photon pairs, a quantum process forbidden classically and semiclassically and enhanced by the graviton number squared $N^2$. We estimate the resulting rates for compact binaries and a stochastic background, including the effect from stimulated decay to the CMB. In theories with light degrees of freedom, an analogous decay into them is also possible, and more relevant for ultralight dark matter, as it can entail huge occupation numbers. We derive first constraints on cosmological GW sources by the corresponding injection of photons from CMB spectral distortions, extragalactic backgrounds, and light-nuclei photofission. In summary, the decay of GWs into photons offers a new (challenging) handle into the detection of GW sources, with the extra appealing feature of being only possible by the quantum nature of the gravitational field.

We present optical photometric and spectroscopic observations of the Type~II supernova SN~2022xus. The SN reached its peak {\em V} band magnitude of $-16.32$ mag within $\sim$7 days of explosion, followed by a plateau phase lasting $\sim$94 days with a declination rate of $\sim$1.2 mag (100 day)$^{-1}$. Early time spectra exhibit broad features that could be caused by the blending of several high-ionisation lines, likely arising from a relatively weak interaction between the SN ejecta and the surrounding circumstellar medium (CSM). Compared to typical Type~IIP SNe, SN~2022xus exhibits a smaller H$α$ absorption-to-emission ratio ($a/e$), indicating a relatively small hydrogen envelope mass at the time of explosion. From nebular-phase spectroscopy and bolometric light curve modelling, the progenitor mass is estimated to be in the range of 12 -- 15 M$_\odot$. The multi-band light curve modelling using \texttt{REDBACK} infers a similar progenitor mass, a low mass-loss rate, and a confined CSM. Although several photometric and spectroscopic characteristics place the SN within the Type~IIL population, it displays mixed properties of both Type~IIP and Type~IIL SNe and cannot be cleanly classified into either subclass. We therefore identify SN~2022xus as a transitional event between Type~IIP and Type~IIL SNe, providing further evidence for a continuum between these two classes.

This contribution considers constraints from analyses of gravitational wave data from binary black hole coalescence, on possible corrections to the Bekenstein-Hawking Area Formula for black hole entropy. Most recent analyses of gravitational wave data from the LVK Consortium appear to confirm the Hawking Area Theorem for black holes at a $5 σ$ accuracy, for the `loudest' signal (SNR of the order of $80$) of binary black hole merger inherent in the recent observation GW250114. Amalgamating this result with Bekenstein's ideas of black hole entropy and the generalized second law of thermodynamics, we constrain leading inverse area corrections for large horizon area spherical black hole solutions of classical $F(R)$ gravity, using the Wald entropy function formalism. The implementation of the observational constraints entails the notion of `absolute consistency' which we introduce and contrast with `relative consistency'. This absolute consistency criterion is shown to relate some of the parameters of $F(R)$ gravity. Next we consider leading quantum general relativistic corrections to the Area formula, arising both from the non-perturbative matter-free Loop Quantum Gravity and matter-dependent, perturbative Entanglement entropy approaches. Combining the leading logarithmic corrections in horizon area (for large areas) from both approaches, and imposing absolute consistency with the observational validation of the Area Theorem, is shown to lead to significant restrictions on the spin and number of species of Beyond Standard Model spectrum of elementary particles, some of which are often assumed to be Dark Matter candidates.

Context. Overall, $γ$ Cas analogues represent a class of OBe stars displaying bright and hard X-ray emission. This emission was recently determined to be the result of accretion onto a companion white dwarf (WD), which might possibly be a magnetic WD. Aims. We present a systematic review of the properties of $γ$ Cas analogues on short-term (kilosecond, ks) scales to further investigate the nature of the X-ray source. In particular, the presence of periodicities could be associated with the rotation of a magnetic WD. Methods. We generated the power spectra and a generalised Fourier algorithm. We applied an epoch folding method, along with Z2n approaches, to 131 X-ray detections of 26 $γ$ Cas analogues and two candidate sources. Results. We identified five sources ($γ$ Cas, $ζ$ Tau, HD45314, V771 Sgr, and $π$ Aqr), with recurrent periodic variability (P $\sim$ 1.2-5.4 ks) across observations. Period values and pulsed fractions are consistent with those reported for intermediate polars. However, while similar periods are found in all exposures of an object, the exact period value or folded light curve shape can vary. We also identify another nine sources displaying periodicities that cannot be confirmed, as there was only one observation available for their analysis. In other cases, periodicities appear (at best) transient and/or marginally significant. Aperiodic variability could be fitted by a power law in 18 of the sources, while the power-law index always is $\sim$ 1, as observed in other accreting WDs. Conclusions. The global properties of the observed short-term X-ray variability of the $γ$ Cas analogues are consistent with those observed from other accreting WD systems.

We present a neural network surrogate model that emulates the NRSur7dq4 gravitational waveform model for precessing binary black hole mergers. The surrogate decomposes the waveform into constituent quantities and trains an independent multilayer perceptron (MLP) for each. We validate the surrogate against NRSur7dq4 on 10,000 waveforms spanning its full parameter space ($1 \leq q \leq 4$, $|χ_{A,B}| \leq 0.8$). For representative total masses between 60 and 300 $M_\odot$, median sky-averaged frequency-domain mismatches range from $8.0 \times 10^{-5}$ to $1.7 \times 10^{-4}$, with 95th percentiles below $10^{-3}$. On an NVIDIA L40S GPU the JAX surrogate evaluates a single waveform in about 1 ms end-to-end, roughly 10 times faster than the LALSimulation C implementation of NRSur7dq4, and sustains about 140 times the LALSimulation throughput at batch size 64, making it well suited for both low-latency parameter-estimation samplers and large-scale waveform generation. The full NRSur7dq4 NN waveform-to-likelihood pipeline is implemented in JAX and is differentiable. This is the first neural-network surrogate of a precessing numerical-relativity waveform model to combine validated NR-faithful accuracy with a fully differentiable, GPU-accelerated inference pipeline, enabling gradient-based inference approaches via automatic differentiation including Fisher information matrices, GPU-accelerated nested sampling, gradient-based MCMC and importance sampling.

Modifications to General Relativity can significantly alter the perturbative response of black holes, leaving imprints on quasinormal-mode spectra, waveform amplitudes and phases, and late-time tails. The parametrized beyond-Teukolsky framework was introduced to capture possible deviations from Kerr dynamics, but the ringdown has so far only been explored as an eigenvalue problem. We present the first time-domain implementation of this framework and perform (2+1)-dimensional scattering experiments with Gaussian wave packets. This approach provides the full linear evolution of the perturbation, from the initial prompt response through the ringdown and into the late-time regime. Using frequency-domain eigenvalue results as benchmarks, we find excellent agreement for low azimuthal numbers, while higher azimuthal numbers are affected by mode mixing, which limits the precision of the extracted modes. We further use the time-domain waveforms to estimate quadratic and mixed coefficients within the linearized modified-potential model, providing a diagnostic for the regime of validity of the linear approximation. Beyond mode frequencies, we show that the deformation parameters can strongly affect the ringdown amplitude and phase, with trends that can be understood from the near-horizon structure of the modified potential. We also analyze the late- time behavior, finding that near-horizon deformations leave the tail exponent unchanged but can substantially shift the onset of the power-law decay. These results demonstrate that time-domain evolutions provide a complementary and flexible framework for testing parametrized deviations from General Relativity in black-hole perturbation theory.

The discovery of S301 (GRAVITY Collaboration et al., 2026) with pericenter distance rp= 280rg and eccentricity e=0.9825, opens the prospect of measuring the spin parameter of Sgr A* through Lense--Thirring (LT) nodal precession. A major obstacle is Newtonian confusion: any non-spherical extended mass distribution can also induce nodal precession. We aim to separate the LT spin signal of S301 from the Newtonian nodal precession. We compare the secular Newtonian torque exerted by a disk or flattened mass distribution on the orbits of S301 and of the apocenter-matched reference stars S2, S55, and S38, using analytic estimates validated by numerical orbit-averaged torque calculations. For a disk or flattened distribution extending beyond the stellar pericenters, the secular Newtonian torque on a highly eccentric orbit is controlled mainly by the apocenter, whereas the LT signal is controlled mainly by the pericenter. Thus stars with apocenters comparable to S301's but much larger pericenters, in particular S2, but also S55, and S38, experience comparable Newtonian torques while having ~ 30 times smaller LT signals (for S2). Their measured precessions, or upper limits on them, can therefore calibrate the mass and orientation of the Newtonian background for subtraction from S301's precession. The Schwarzschild apsidal advance of S301 further rotates the orbit's pericenter relative to any disk, producing a systematic time dependence in the Newtonian contribution, while the LT signal remains fixed by the spin vector. Granularity of the perturber population sets a stochastic floor on this subtraction, which orbit- and star-averaging suppress. With continued GRAVITY+ astrometry and Extremely Large Telescope (ELT) spectroscopy, the in-plane spin projection may be within near-term reach; the full spin vector requires a much longer-term accumulation of the LT apsidal signal.

In recent years, Gaia has been the primary driver of the expansion of the white dwarf (WD) initial-final mass relation (IFMR) in open clusters. The increased sample size has highlighted a pronounced observational gap at progenitor masses of $\simeq2$--$2.7\,M_\odot$, with no spectroscopically confirmed cluster-member WDs in this range. Analysis of the Milky Way open cluster census shows that this absence is primarily driven by the scarcity of appropriately aged, nearby clusters capable of hosting Gaia-detectable WDs, implying that deeper, targeted photometry will be required to build a substantial sample in this progenitor mass range. We further searched for previously unexamined Gaia WD candidates in clusters with ages consistent with producing gap progenitors and identified two viable targets, which we observed spectroscopically with Gemini GMOS-N. Both targets yield inferred progenitor masses within the observational gap, making them the first spectroscopically confirmed cluster-member WDs in this progenitor mass range. The NGC 6991 candidate, in particular, is confirmed as a DA WD with an inferred progenitor mass of $2.12^{+0.04}_{-0.15}\,M_\odot$, providing further support for a non-monotonic trend in the IFMR.

We investigate the end stages of circular white-dwarf--compact-object binaries by developing a novel integrator implementing mass transfer and 2.5-order Post-Newtonian kinematics. White-dwarf--compact-object binaries are subject to two phases: a slow inspiral during which binary evolution is dominated by weak-gravity radiation reaction and a quicker ``outspiral" dominated by mass transfer. These systems have unique gravitational waveforms with several characteristic features including an accumulation of signal near the maximum cutoff frequency set by the transition between in- and outspiral. We investigate trends in gravitational wave parameters based on component masses. In particular, maximum cutoff frequency depends strongly on white dwarf mass and compactness. It is unlikely that extragalactic binaries will be measured by LISA or current or future terrestrial detectors. However, white-dwarf--compact-object binary end stages will be an important source for future decihertz detectors such as DECIGO and LGWA: The final inspiral of tens of white-dwarf--neutron-star binaries will be detected annually by LGWA, and millions of inspirals along with thousands of outspirals will be detected by DECIGO. The ultimate fates of these binaries are diverse and dependent upon the intricacies of angular momentum loss. In particular, we show that white dwarfs with partners of sufficiently low/high mass can end their lives in common envelopes/mergers, while white dwarfs do not enter contact with partners of intermediate mass. The highest frequencies produced by white-dwarf--compact-object binaries in our tests are 10--20 Hz---incapable of mimicking sub-solar-mass compact object signals in terrestrial detectors or explaining S251112cm-like signals.

We study equilibrium sequences of magnetized strange dwarfs composed of a self bound MIT bag strange matter core, with \(B_{\rm bag}^{1/4}=145\,{\rm MeV}\), and an ordinary crystalline crust. The aim is to determine how nuclear composition changes and magnetic pressure anisotropy in the crust modify the mass radius relation. The strange core is kept isotropic, while the crust is described either by pure nuclei stopped at the first inverse beta threshold or by electron capture sequences extended to neutron drip for C, O, Ne, and Mg compositions; selected mixed crusts are also considered up to the first instability. The stellar structure is solved with the radial pressure as the integrated pressure and with the anisotropic contribution \(2(P_t-P_r)/r\) restricted to the crust. This treatment is compared with ordinary white dwarf sequences and with scalar pressure branch calculations. We find that extending the crust to neutron drip produces more compact strange dwarf branches than stopping at the inverse beta threshold, because the evolved crust is softer and the core crust transition occurs at higher pressure. Magnetic anisotropy further shifts the selected branches toward smaller radii, with the effect visible across the compositions studied and clearer at fixed stellar mass. The comparison with compact objects from the Montreal White Dwarf Database is used only as an observational reference plane, but it indicates that compact white dwarf candidates are a relevant region for testing small core strange dwarf scenarios.

Galactic compact binaries are expected to form a dominant foreground in the millihertz band of the Laser Interferometer Space Antenna (LISA). Residual power from injected sources that do not meet the adopted recovery criteria can bias stochastic gravitational-wave background (SGWB) inference or increase its uncertainty. We use LISA Data Challenge 2A Sangria injections and the Erebor comparison table to construct a catalog residual spectrum between 0.4 and 6.0 mHz with orbit-averaged long-wavelength Michelson \(X\) source powers. The source power concentration in each frequency bin determines the excess kurtosis of a random-phase source sum; instrumental noise and fiducial SGWB power strongly reduce the resulting excess kurtosis in most bins. The residual spectrum also overlaps an isotropic power-law SGWB in the mean binned power. We use a fixed covariance obtained by summing independent Fourier-mode power variances. For a frequency-independent SGWB with fiducial amplitude \(Ω_0=10^{-11}\), marginalizing over the dimensionless residual-power factor \(β\) increases the \(Ω_0\) uncertainty by \(13.6\%\) when the residual power is distributed uniformly over the Fourier frequencies in each bin. The largest Gaussian prior standard deviation on \(β\) that limits this increase to \(10\%\) is \(0.0073\). More concentrated distributions of the residual power among Fourier frequencies reduce the increase, reflecting unresolved frequency structure. Omitting the fiducial residual with the covariance held fixed shifts the best-fitting \(Ω_0\) by \(119.5\) times the uncertainty obtained with \(β\) fixed. This projection of the residual spectrum onto the SGWB spectrum is not a posterior detection significance. The numerical values are conditional on the catalog-level scalar power model, fixed instrumental noise, and independent mode-power covariance.

Young Stellar Objects (YSOs) exhibit strong X-ray emission, widely attributed to magnetic reconnection and magnetospheric accretion; however, owing primarily to limited photon statistics, observational tests of these mechanisms have often relied on simplified analyses, leaving room for more precise constraints on their emission processes. We aim to derive the X-ray properties of X-ray-bright YSOs selected from multiple star clusters and investigate their emission mechanisms through an approach from multiple perspectives based on timing and spectroscopic analysis. We performed a systematic search of XMM-Newton archival observations and constructed a sample of 51 X-ray-bright YSOs for timing and spectroscopic analyses. We identified quiescent and outburst phases through timing analysis, performed phase-resolved multi-temperature spectroscopy. Multi-temperature plasma structures are detected in both quiescent and outburst emission. The relationships among the timing and spectral parameters are broadly consistent with a magnetic-reconnection scenario. Comparison with Gaia DR3 stellar parameters suggests that magnetospheric accretion alone has difficulty explaining most of the fitted X-ray temperatures, although the coolest model components with $kT \lesssim 0.3$ keV may include an accretion-shock contribution. After separating these low-temperature components, the remaining quiescent components show a clearer positive correlation in the $EM$--$kT$ plane, with magnetic-loop lengths distributed around $10^{12}$ cm. Neupert-like behavior, the temporal evolution of temperature and emission measure, the Rossby-number activity relation, and positive correlations between quiescent and outburst properties all suggest that magnetic reconnection plays a key role in both phases.

The AM CVn class includes mass transferring, ultra-compact double white dwarf binaries with orbital periods on the timescale of minutes. A long-standing puzzle is that none of the roughly fifty ultra-compact, "verification binaries" which are easily detectable in the millihertz gravitational wave regime reside in a triple star configuration. Much evidence has hinted at V407 Vul being an inspiraling, double white dwarf AM CVn with an orbital period of 569s. Yet, a decisive confirmation has proved challenging since a main sequence star dominates its visible spectrum. We present a clear confirmation of the triple star nature of the source by detecting a significant astrometric wobble of the photocentre on the 569s orbital period of the binary. The AM CVn and the main sequence components are gravitationally bound with a spatial separation of roughly 0.03-0.04'', equating to an orbital separation of approximately 120AU. A total of 23 years of orbital timing constrained the orbital decay of the AM CVn as being precise to the 1% level, critical in understanding if this class of binary survives through a period minimum or coalesce. New Hubble Space Telescope ultra-violet imaging and spectroscopic data allowed the isolated detection of the AM CVn at shorter wavelengths, revealing an approximately 58000 K accretor white dwarf, while placing a firm distance constraint of 3510+140-110 pc. At this distance, we predict that the Laser Interferometer Space Antenna (LISA) will detect V407 Vul with a 28.4+-9.2 signal-to-noise ratio in a 4yr mission time, making it the first verification binary with an outer tertiary, or "verification triple", detectable for millihertz gravitational wave observatories.

We present spatially resolved X-ray spectroscopy of the Type Ia supernova remnant 3C 397, one of the most promising candidates to have originated from a white dwarf with a mass close to the Chandrasekhar limit. The remnant was observed during the performance verification phase of the X-ray Imaging and Spectroscopy Mission (XRISM), with the field of view of the Resolve calorimeter array positioned on the eastern half of the remnant. We divide the Resolve field of view into southeastern and northeastern regions and extract spectra from each region for both Resolve and Xtend. The Resolve spectra are characterized by narrow K-shell emission lines from intermediate-mass elements (IMEs) such as Si, S, Ar, and Ca, and by broader K-shell emission lines from iron-group elements (IGEs) such as Cr, Mn, Fe, and Ni. K-shell emission lines from Ti and Cr are also detected, and are found to be locally enhanced in the southeastern region, as reported in previous observations. We model the Resolve and Xtend spectra simultaneously by a non-equilibrium ionization (NEI) plasma model with multiple temperatures and ionization states. The observed mass ratios of Ti/Fe and Cr/Fe in the southeastern region can only be explained by nucleosynthesis in a neutron-rich environment produced by electron-capture reactions in the innermost layers of the exploding white dwarf. By comparing the observed mass ratios with those predicted by nucleosynthesis models, we constrain the central density to be >= 4.0 x 10^9 g cm^{-3} for the deflagration-to-detonation transition model and >= 6.0 x 10^9 g cm^{-3} for the pure turbulent deflagration model. On the other hand, the observed Ni/Fe mass ratio is globally enhanced across the field of view, suggesting an additional neutronization mechanism beyond electron-capture reactions, such as a higher progenitor metallicity.

We highlight the potential for synergies between the SKA telescopes and ALMA, which will begin to be significant already with SKA Early Science. Broadly within star formation science, we focus on 1) (simultaneous) time domain and variability studies (e.g., of (proto-)stars), which is systematically opening a new observing window that will enable us to better constrain the physics of extreme stellar flares and their interplay with mass accretion in young stars, 2) possibilities for complementary coverage of different transitions of molecules as tracers of the ISM (e.g., H2CO to trace density and temperature), and 3) radio recombination lines to trace ionised gas at different densities. Furthermore, we address synergies in terms of the spatial resolution of both observatories and new capabilities not only on the SKAO side but extending to the ALMA2030 wideband sensitivity upgrade.

We present an ALMA 1.3~mm dust continuum study of the dense core mass function (CMF) in Sh2-284, a low metallicity outer Galaxy star-forming complex with $Z\sim1/3$--$1/2~Z_\odot$. The observations cover six far-infrared bright subregions at $\sim$0.65" (3000~au) resolution. We identify a total of 91 candidate dense cores and define a robust catalog of 68 cores with Gaussian fitting. The high-mass CMF above 2.5 Msun is well described by a Salpeter-like slope, with a fiducial forward-modeled value of $α=1.22^{+0.24}_{-0.22}$ for $dN/d\log M\propto M^{-α}$. Together with existing constraints on the initial mass function (IMF) of Sh2-284, the Salpeter-like CMF is consistent with a resemblance between the CMF and IMF shapes in the outer Galaxy environments, suggesting that moderately low metallicity alone does not strongly reshape the high-mass CMF/IMF slope.

Following the previous wor k[1] here we consider early thermal evolution of hot strange stars made of color superconducting quarks in two different pairing states: two-flavor color superconductor (2SC) and color-flavor-locked (CFL) phases, taking into account cooling by neutrinos and electron-positron pair creation due to the Schwinger process. We show that Schwinger luminosity in the electrosphere is a universal function of temperature, independent of quark matter phase for quark chemical potential $μ_q>280$ MeV. The surface of a strange star in all the cases cools faster than its interior. This leads to a fast decrease of pair luminosity with time, so that it does not exceed $10^{46}$ erg/s at 1 second after strange star formation. Neutrino luminosity dominates over pair luminosity in all the cases except for the CFL phase with a large gap parameter $Δ>60$ MeV, where there is a strong suppression of neutrino emission. The total energy emitted in electron-positron pairs is always smaller than the energy emitted in neutrinos, but they become comparable for the large gap parameter.

Changing-look active galactic nuclei (CL-AGN) provide a direct way to study accretion and spectral-state changes on timescales of months to years. Still, the known population remains scattered across heterogeneous literature samples. We present a compilation of a homogenized catalog of known CL-AGN and related candidates, designed as a traceable reference database for time-domain and multiwavelength studies. After coordinate homogenization, duplicate removal, and validation, the optical parent catalog contains 1,438 unique sources, including 987 spectroscopically confirmed CL-AGN and 451 candidate or photometrically selected systems. We augment the catalog with ancillary information from radio/mm, infrared, ultraviolet, X-ray, and gamma-ray data sets using nway and survey-specific quality criteria. The resulting database includes 188 sources in the broad radio layer, 9 RFC/VLBI compact-core matches, 16 sources with ALMA archival coverage, 1,353 infrared counterparts, 918 GALEX ultraviolet matches, and 576 X-ray counterparts. We also identify 9 Fermi-LAT candidate associations. Overall, 1,385 sources have at least one non-optical counterpart, and 75 have coverage across the four main ancillary regimes: radio, infrared, ultraviolet, and X-ray. As a first application, we identify 70 confirmed CL-AGN within the LSST Wide--Fast--Deep footprint and 5 within the Rubin Deep Drilling Fields, and provide the up-to-date, ~116-day ugrizy Rubin lightcurve for SDSS J095902.76+021906.3 (z=0.34579) and discuss the early data inferences. This catalog is envisioned to be community-driven and provides a dynamic, expandable resource for target selection, population comparisons, and future Rubin-era CL-AGN studies.

Coronal dimmings, or transient coronal holes, are manifested as a sudden reduction in extreme ultraviolet (EUV) and X-ray emission, often following solar eruptions. We investigate whether a dimming event can produce coronal hole-like plasma characteristics by comparing imaging and spectroscopic observations from Solar Orbiter, Hinode, IRIS, and SDO prior and during the dimming. The SDO/AIA 193 Å emission intensity in the dimming region was reduced to the same level as the neighbouring coronal hole within 11 hours. The Doppler velocity measured with Fe XII (corona) decreased from $-0.34^{+0.37}_{-0.27}$ km/s towards a predominant upflow of $-3.2^{+0.4}_{-0.6}$ km/s. The first ionisation potential (FIP) bias was reduced towards photospheric values. We found an increase in the number of automatically detected EUV brightenings near the dimming boundary in SDO/AIA 193 Å which could be a sign of magnetic reconnection. In the cooler SDO/AIA 171 Å or Solar Orbiter HRI_EUV 174 Å channel, we did not observe such an increase. Coronal bright points (CBPs) appeared relatively unaffected by the formation of the dimming. The Mg II $k_3$ (chromosphere) Doppler velocities were unchanged, except for a small reduction in the dimming upflows in areas with weak magnetic fields ($<20$ G). We find that the dimming only shows partial coronal hole-like properties; specifically, in the coronal emission lines and at temperatures of $>1$ MK. We suggest that this is due to the dimming resulting from plasma depletion only at higher altitudes. Since the CBPs were not significantly impacted by the dimming, we used their magnetic loop heights ($\sim 10$ Mm) as the lower limit to the dimming height. Our findings provide new insights into the atmospheric structure of coronal dimmings.

Binary interactions are expected to play a major role in shaping the progenitor population of core-collapse supernovae, particularly in the era of deep, high-cadence transient surveys. Using ComBinE, a rapid binary population synthesis code combining tabulated stellar structure models with physically motivated mass-transfer stability criteria, we find that ~40% of Type II supernova progenitors at Milky Way metallicity originate from mergers between a post-main-sequence star and a main-sequence companion following unstable mass transfer. Compared to single-star progenitors with the same helium-core mass, these merger products have more massive hydrogen-rich envelopes and broader envelope-mass distributions. Their envelopes are helium-enriched, with relative enhancements of up to 80% and helium mass fractions reaching 0.4. These differences are expected to affect Type IIP light curves and should be considered in future progenitor and explosion models. Constraining the merger-induced Type IIP fraction with facilities such as LSST, Roman, and the ELT will provide insights into binary evolution physics.

We analytically determine the leading backreaction of a spherically symmetric massive complex scalar quasi-bound state (with mass $μ$) on a Schwarzschild black hole with (initial) gravitational radius $r_0$. Working in the small-coupling regime, $r_0 μ\ll 1$, we evaluate the stress-energy tensor of the fundamental scalar $s$-wave and solve the Einstein equations through quadratic order in its amplitude in ingoing Eddington-Finkelstein coordinates. We also determine the small-mass quasi-resonant frequency of the fundamental $s$-wave analytically by matched asymptotic expansions and validate it numerically using Leaver's method. Unlike steady-state treatments, the calculation retains the exponential decay of the quasi-bound state. We obtain explicit expressions for the metric perturbations and Misner-Sharp mass and derive the evolution of the future outer trapping horizon. The black-hole mass grows monotonically with the decaying horizon flux and saturates when the finite scalar cloud has been absorbed, with the decrease of the cloud mass exactly balancing the horizon growth at the perturbative order considered. We also determine the domain in which the scalar small-coupling approximation and the gravitational perturbative expansion are simultaneously valid.

Mass functions are used in all areas of astrophysics. The stellar initial mass function (IMF), in particular, plays a central role in modeling stellar populations in galaxies. However, few dedicated tools for working directly with the IMF and its precursor functions are widely available. We present the $\texttt{imf}$ package, a Python library integrated into the wider scientific Python ecosystem that implements common and variant forms of mass functions, especially the IMF and its pre- and protostellar equivalents, as probability distribution functions based on SciPy's statistics architecture. This package enables the performance of operations such as sampling and integration on a wide array of highly customizable mass functions. $\texttt{imf}$ is publicly available on the Python package index $\texttt{pypi}$ under the project name $\texttt{initial_mass_function}$.

The growing sensitivity of gravitational-wave detectors enables increasingly precise tests of black hole (BH) ringdown spectroscopy. BH quasinormal modes (QNMs) are, however, spectrally unstable: small near-horizon modifications can produce a drastically different QNM spectrum, while causality requires the prompt ringdown to remain BH-like until the reflected signal returns. Quantum BHs with substantial interior reflection provide a natural setting for this tension, yet the relation between their time-domain waveform and different QNM spectra still lacks a consistent picture. In this work, we systematically examine the time-domain Green function for quantum BHs, considering sources located outside and inside the light-ring potential barrier. By decomposing the Green function into causally distinct components and choosing the corresponding inverse-Laplace contours consistently, we clarify how the response is built from different sets of QNMs. We find that the quantum BH QNM reconstruction always faithfully describes the signal once the curved spacetime is probed, but its practical efficiency depends strongly on the evolutionary stage. Before interior reflection becomes relevant, we prove that this basis is formally equivalent to the BH QNM and tail expansions, with convergence properties sensitive to source location. At late times, the long-lived modes provide an efficient basis. Time-domain simulations confirm these results, providing a unified causal framework for BH spectroscopy and quantum BH seismology.

We construct a minimally modified gravity theory that propagates only two tensorial gravitational degrees of freedom around a spatially flat Friedmann--Lemaître--Robertson--Walker (FLRW) background and admits a predictive cosmological perturbation theory. We first show that, in the original four-constraint construction, the homogeneous values of the Lagrange multipliers are not fully determined and nevertheless enter the quadratic tensor action, thereby obstructing cosmological predictivity. We remove this ambiguity by coupling the auxiliary constraints to spatial Laplacians of the multipliers. The multiplier sector then drops out of the homogeneous background equations while continuing to constrain the inhomogeneous scalar sector. The tensor dispersion relation generically contains both $k^{2}$ and $k^{4}$ contributions, whereas no propagating gravitational vector or scalar mode is present on the generic branch for which the constraint reduction is nondegenerate. We subsequently study a subclass whose gravitational Hamiltonian density is proportional to the lapse and contains cubic momentum invariants. In this subclass the $k^{4}$ tensor term vanishes and the lapse can be absorbed into a time redefinition at the background level. After coupling a canonical inflaton, the only propagating scalar mode is the inflaton fluctuation, with unit sound speed. For a quadratic potential, departures from general relativity shift the scalar spectral index, while a tensor speed $c_{T}>1$ suppresses the tensor-to-scalar ratio according to $r=16ε_{s}/c_{T}$. The parameter regions compatible with the observational bounds adopted in this work require a superluminal tensor speed; however, very large $c_{T}$ simultaneously reduces the tensor kinetic coefficient and may lower the perturbative cutoff, although determining the actual strong-coupling scale requires a nonlinear analysis.

Pulsar timing arrays (PTAs) are sensitive to ultralight dark matter (ULDM) in the $10^{-24}$-$10^{-20}\,\mathrm{eV}$ mass range, with existing datasets already probing otherwise open parameter space and future PTAs promising substantial improvements in reach. Thus far, however, PTA searches for ULDM have typically been formulated using limiting descriptions. Analyses are performed in either the fully correlated limit, in which the local ULDM amplitude is shared across the array, or the fully uncorrelated limit, in which each pulsar has an independent local amplitude. Because the transition between these regimes occurs within the PTA-sensitive mass range, projected sensitivities and data-derived constraints can depend on which limiting description is assumed. For the first time, we develop a self-consistent analysis that treats the ULDM field as a Gaussian random field with finite spatial correlations, allowing the amplitude prior used in PTA signal models to interpolate continuously between the fully correlated and fully uncorrelated limits. We apply the framework to both linearly and quadratically coupled scalar ULDM, the latter including the universal gravitational signal sourced by the oscillating ULDM pressure. Pulsar-distance uncertainties are incorporated through an augmented latent-field prior, and the resulting distance-marginalized latent-amplitude distribution is represented with a normalizing-flow surrogate. We validate the method on mock PTA datasets, including blinded signal injection tests.

Context. Gamma-Loud Protostars (GLPs) have been recently reported as Galactic hadronic accelerators whose acceleration site is situated in their protostellar jets. Theoretical and observational analysis situate radio cm luminosity as a thermal tracer of jet activity, presenting an unique opportunity to study jet properties as accelerators. Aims. We aim to develop a way to estimate the kinetic power of protostellar jets and compare their energetics with those extracted from the non-thermal gamma-ray side of GLPs. Methods. We combine theoretical and phenomenological relations to estimate the jet mechanical luminosity based on the radio cm luminosity. We relate the resulting values to the non-thermal contribution of GLPs, studying its behaviour and efficiency. Results. The derivation of the jet power successfully reproduces infrared and radio observations. The cosmic-ray energy correlates to the injected mechanical energy, implying an acceleration efficiency of 1--10%. Future radio observations are needed to find the definite accelerators and obtain reliable efficiencies.

We study the rotational Unruh effect by identifying the pseudodynamics which emerges when fundamental spacetime symmetries are violated. We show that there is, fundamentally, no rotational Unruh effect, in agreement with the first explicit calculations of the literature, and that, when such an effect has been claimed to exist in later articles, its origin traces back to the derivation of the standard Unruh effect involving linear acceleration. Such a linear Unruh effect intrudes because the chosen reference frames do not respect the cylindrical symmetry of the system, and thus the analyses require Lorentz boosts. Our study also confirms previous findings that the Unruh effect is a consequence of the pseudodynamics which arises because Instant-Form dynamics explicitly breaks a fundamental symmetry of spacetime: Poincaré invariance.

Numerical simulations of gravitational waves (GW) production during violent evolution of matter inhomogeneities in the early Universe yield highly wiggle infrared parts of the spectra. Obtained directly from the two-point correlation function, these wiggles are nonphysical, corresponding to the parasitic, double frequency terms in naively averaged squared oscillation amplitudes of GW, and hence must be washed out. The deep infrared behavior can be predicted on general grounds, e.g. fixed by causality considerations. However, what matters for real observations, e.g. like that of NANOGrav, and what can be only inferred from numerical simulations, is the infrared slope near the maximum of the spectrum. It reflects the dynamics responsible for the GW production in its heyday, and hence must be accurately predicted. We illustrate the problem with numerical simulations of the Domain Wall network performed with the help of code CosmoLattice. We suggest a numerical procedure to smooth out these parasitic wiggles, which allows us to recover the true spectrum. Being quite generic, it may be applied to numerical simulations of other hypothetical sources of GW possibly operating in the early Universe. The procedure requires to extend the simulation by a few Hubble times after termination of the GW production. We checked with numerical simulations, that the technically natural long-time extension of simulations, which becomes available via artificial scaling of different parts in the scalar sector equations provided by PRS prescription, gives wrong GW spectra even if the source terms are properly rescaled.

Strong magnetic fields modify the thermodynamics of white dwarf (WD) matter by quantizing the transverse motion of degenerate electrons into Landau levels and splitting the pressure into components parallel and perpendicular to the magnetic field. We investigate how this microscopic pressure anisotropy affects ultra-dense WD sequences when Coulomb lattice contributions, electron capture thresholds, neutron drip limits, and nuclear composition are treated consistently in the equation of state (EoS). The stellar equilibrium structure is obtained by solving an anisotropic extension of the Tolman--Oppenheimer--Volkoff (TOV) equations, where $P_r = P_\parallel$ and $P_t = P_\perp$ denote the radial and tangential pressures, respectively. We compare the post-electron-capture branches with their corresponding pre-capture sequences for pure $^{12}\rm{C}$, $^{16}\rm{O}$, $^{20}\rm{Ne}$, and $^{24}\rm{Mg}$ compositions, as well as for fixed 50/50 C/O, Ne/O, and Mg/Ne mixtures. The EoS predicts $P_\perp < P_\parallel$ in density ranges where only a few Landau levels are occupied. Consequently, pressure anisotropy shifts the stellar sequences toward smaller radii, with only minor changes in the maximum masses. We also find that post-capture configurations cannot be interpreted from the mass--radius plane alone, since the corresponding $M(ρ_c)$ curves reveal unstable portions after the maximum mass is reached. Our results show that strong magnetic fields significantly reduce the radii of low-mass WDs, yielding better agreement with the observational data available in the Montreal White Dwarf Database and suggesting that future high-precision observations of massive magnetic WDs could help assess the role of magnetic pressure anisotropy in determining their masses and radii.

Recent pulsar timing array (PTA) results have provided evidence for the presence of a nanohertz gravitational wave (GW) background, most likely originating from a population of supermassive black hole binaries (SMBHBs). The next major milestone is the detection of continuous GWs (CGWs) from an individual SMBHB and the identification of its electromagnetic counterpart. Typically, searches for CGWs in PTA data assume binaries in circular orbits. However, theoretical studies indicate that binaries emitting GWs in the PTA frequency band may retain significant eccentricity. In this paper, we present a fast and efficient Bayesian pipeline to search for CGWs from individual SMBHBs in relativistic eccentric orbits in PTA datasets. Our approach extends the QuickCW framework for circular binaries, in which model parameters are divided into projection and shape parameters. Computational efficiency is achieved by performing many updates of the projection parameters for a fixed set of shape parameters, an operation that is orders of magnitude faster than updating the shape parameters. We validate the pipeline through both detection and upper-limit analyses of simulated PTA datasets. This framework makes the search for eccentric SMBHBs computationally feasible, even in the next-generation PTA datasets with many more pulsars.

One of the most promising targets for pulsar timing arrays (PTAs) is identifying an individual supermassive black hole binary (SMBHB) out of the population of binaries theorized to produce a gravitational wave background (GWB). In this work, we emulate an evolving PTA dataset, complete with an increasing number of pulsars and timing baselines, into which we inject a single binary on top of a Gaussian GWB signal. We vary the binary's source parameters, including sky position and frequency, and create ten noise realizations for each source/PTA combination to synthesize an ensemble of simulated datasets with which we assess current Bayesian binary search techniques. We develop a novel, cross-correlation based model tuned for individual SMBHBs and compare its binary detection and characterization capabilities to two waveform-based template models. This spike pixel (SP) technique is designed to identify the frequency-specific anisotropy induced by an individual SMBHB. We find that a template-based search, including the full gravitational wave signal structure (i.e., both the Earth and pulsar effects of an incident GW) returns the highest Bayes factors (BF) and has the most robust parameter estimations. SP attains a realization-median <inline-formula><mml:math><mml:mrow><mml:mi>BF</mml:mi><mml:mo>&gt;</mml:mo><mml:mn>10</mml:mn></mml:mrow></mml:math></inline-formula> at source strengths <inline-formula><mml:math><mml:mrow><mml:mn>7</mml:mn><mml:mo>&lt;</mml:mo><mml:mo>(</mml:mo><mml:mi>S</mml:mi><mml:mo>/</mml:mo><mml:mi>N</mml:mi><mml:mo>)</mml:mo><mml:mo>&lt;</mml:mo><mml:mn>15</mml:mn></mml:mrow></mml:math></inline-formula>. Interestingly, despite being a deterministic model, the Earth-term template struggles to identify and characterize low-frequency binaries (i.e., at 5 nHz). These binaries require higher source strengths (<inline-formula><mml:math><mml:mrow><mml:mn>16</mml:mn><mml:mo>&lt;</mml:mo><mml:mo>(</mml:mo><mml:mi>S</mml:mi><mml:mo>/</mml:mo><mml:mi>N</mml:mi><mml:mo>)</mml:mo><mml:mo>&lt;</mml:mo><mml:mn>19</mml:mn></mml:mrow></mml:math></inline-formula>) to reach the same BF threshold. This is likely due to neglected confusion effects between the pulsar and Earth terms. By contrast, the SP shows promise for parameter estimation despite treating a binary's GW signal as excess directional GW power without phase modeling. Sky location and frequency parameter constraints returned by the SP are only surpassed by the Earth-term template model at <inline-formula><mml:math><mml:mrow><mml:mo>(</mml:mo><mml:mi>S</mml:mi><mml:mo>/</mml:mo><mml:mi>N</mml:mi><mml:mo>)</mml:mo><mml:mo>∼</mml:mo><mml:mn>12</mml:mn><mml:mi>─</mml:mi><mml:mn>13</mml:mn></mml:mrow></mml:math></inline-formula>. Milestones for a first detection using the full-signal GW model are included in a following paper, Petrov et al. [Expectations for the first supermassive black-hole binary resolved by PTAs. II. Milestones for binary characterization, Phys Rev. D 114, 023033 (2026).10.1103/zp2x-r4mp].

We present TempLat, a C++ framework for lattice field theory simulations in arbitrary dimensions. Its symbolic language, built on expression templates, translates mathematical expressions almost verbatim into C++ while compiling to highly optimized kernels, in contexts ranging from classical-statistical to Monte Carlo simulations. TempLat is performance-portable: building on Kokkos, it supports large CPU clusters, as well as NVIDIA and AMD GPUs. Its abstraction of hardware into a device concept makes TempLat extensible to future architectures. We demonstrate excellent strong and weak scaling on both CPUs and GPUs. We also present ParaFaFT, a standalone parallel discrete Fourier transform library supporting arbitrary dimensions on all of the above hardware, and benchmark its scaling. Both are open source and available on GitHub, and power a new release of CosmoLattice, a widely used early-universe simulation library now available on GPUs.

At microscopic scales the linear response of thermal states of large-$N$ CFTs is governed by a thermal operator product expansion (OPE), while at large scales response is governed by collective excitations known as quasinormal modes (QNM). We show that the OPE and QNM representations of the retarded correlator in mixed time and spatial momentum coordinates have an overlapping region of convergence in the complex time plane, giving a map between OPE and QNM data. We show that large-overtone QNM asymptotics are related to OPE singularities, while low-overtone QNM data appear in analytic continuation from short to large times. Using this approach we obtain new analytic results for QNM asymptotics, and numerically obtain low-overtone QNMs from OPE data for the Schwarzschild-AdS$_5$ black brane. We further show that the OPE spectrum is intimately related to QNM data through a set of sum rules which we derive in Mellin space. Finally, using the lightcone OPE, we argue that stress tensor correlators at large spatial momentum thermalise slower as the conformal collider bounds approach saturation. This work points to a new thermal bootstrap programme where OPE and QNM data constrain each other.

Quasars are among the most luminous objects. They are powered by accretion onto supermassive black holes. They are thought to impact cosmological evolution primarily through energetic winds, known as quasar-mode feedback, yet the efficiency and spatial extent of this process remain poorly constrained. Here we present X-Ray Imaging and Spectroscopy Mission (XRISM) observations of H1821+643---the nearest galaxy cluster with a central quasar (redshift z = 0.297)---which was a rare opportunity to directly probe quasar-mode feedback in the intracluster medium. High-resolution spectroscopy reveals exceptionally broadened Fe XXV emission lines from the intracluster medium, with a velocity dispersion of approximately 300 km/s, far exceeding values observed in nearby cluster cores. These lines originate predominantly at radii of 20-100 kpc from the centre. Assuming that turbulence from a quasar-driven shock led to the broadening of the lines, the energy injected by the quasar beyond galactic scales ($\gtrsim$20 kpc) is estimated to be $\gtrsim$1-10% of its radiative energy. Notably, this feedback efficiency exceeds previous multiwavelength estimates by orders of magnitude ($\lesssim$0.01%) and reaches the levels required by the latest cosmological hydrodynamical simulations. This finding of vigorous turbulence indicates that quasar-mode feedback plays a central role in regulating galaxy and cluster evolution at high redshift.

Line intensity mapping measures the combined emission of atomic and molecular lines from unresolved galaxies, offering a way to map cosmic structure across enormous volumes. A single observed frequency, however, contains emission from several spectral lines at different redshifts. These interlopers are usually removed before cosmological inference. We show that this removal is not always optimal. Once the possible emitting lines and their redshifts are included in the model, interlopers become additional tracers of large-scale structure at other epochs, projected into the coordinate system of the target line. We formulate interloper treatment as a Fisher decision problem, requiring both improved precision and parameter bias below a chosen tolerance. In SPHEREx forecasts for H$α$ with [O III], H$β$, and [O II] interlopers, and in FYST forecasts for [C II] with CO interlopers, $Ω_m h^2$ and baryon acoustic oscillation (BAO) distance measurements are comparatively robust to astrophysical calibration errors, whereas the clustering amplitude $σ_8$ and the dark energy parameters $w_0$ and $w_a$ are more sensitive to the adopted line model and priors. The BAO distance measurement gives a simple physical picture: modeling interlopers turns two observed bands into a transverse BAO distance ladder over $0.7\lesssim z\lesssim5.8$. Interlopers are therefore not only contaminants to remove, but a calibrated component of the cosmological signal model for future LIM surveys.

We present Syntriod, an orbital-phase domain radial velocity (RV) template-based algorithm designed to provide robust initial orbital parameter estimates for spectroscopic binaries across diverse observational sampling conditions. Rather than performing full orbital inference, Syntriod constrains the parameter space with physically consistent solutions to guide subsequent optimization procedures. We evaluate its performance using 10,000 synthetic Keplerian orbits spanning diverse configurations and sampling regimes. For well-sampled datasets ($N_{obs} \ge 8$), Syntriod recovers orbital periods with relative accuracies of order $10^{-3}$. At the theoretical sampling limit ($N_{obs} = 6$), the method maintains a ~94% success rate, while classical period-search techniques like Lomb-Scargle become increasingly affected by aliasing. Even below this limit ($N_{obs} = 5$), Syntriod recovers the correct orbital solution in ~83% of cases, showing gradual degradation rather than catastrophic failure. We further evaluate the method on 12 real spectroscopic binary systems (HD 160934, Phi Cyg, Capella A, Kepler 16, KIC 3858884, KIC 6867766, KIC 2445134, KIC 3003991, DU Boo, HL Dra, FP Boo, and AK Her) spanning broad orbital periods and eccentricities. Syntriod consistently reproduces literature solutions even when datasets are randomly subsampled to sparse regimes. Where a full Keplerian solution becomes underconstrained ($N_{obs} \le 4$), the algorithm transitions to linear dynamical relations, recovering parameters such as mass ratio ($q$) and systemic velocity ($γ$) with success rates exceeding 99%. These results demonstrate that Syntriod provides reliable, computationally efficient initial parameter estimates across well-sampled and sparse regimes, making it a practical pre-solver for modern orbit-fitting pipelines and large spectroscopic surveys.

The initial conditions of our Universe contain a wealth of information about the particle physics of very high energies. One such class of signatures, called cosmological colliders, generates oscillations in the three-point correlations (or bispectra) of the primordial density field, and these imprint scale-dependent oscillations in the halo bias. We develop a new method for simulating cosmological collider models that foregoes traditional template-based basis-decomposition methods and can reproduce the scale-dependent signals of the input template at percent-level accuracy. Using this method, we produce simulations for one class of collider models and present the first measurements of oscillating halo bias in simulations. The amplitude and phase of the oscillations show a clear dependence on halo mass, with a factor of ten shift in halo mass causing a factor of two shift in the location of the oscillations. Increasing the frequency of the primordial bispectra model suppresses the signal in the halo bias, as the oscillations average down over the window function of the halo. The phase of the signal is also sensitive to assembly bias. In all cases, the scale-dependent halo bias can be accurately modeled using a simple peak background-split theory. The oscillations and their mass/selection-dependent phase offsets are a unique signature that is not easily mimicked by known observational systematics and is therefore a more robust target. Our simulations and underlying initial conditions code are both made publicly available.

While the standard $Λ$CDM paradigm is in excellent agreement with most current cosmological observations, theoretical challenges surrounding the cosmological constant ($Λ$) have strongly motivated the exploration of dynamical dark energy (DE) and modified gravity (MG) models. Investigating the physical nature of the cosmic acceleration requires N-body simulations to probe the non-linear growth of cosmic structure and prepare for the high-precision data from Stage-IV surveys. In this paper, we present EFT-RAMSES, a comprehensive extension of the ECOSMOG cosmological simulation code designed to explore non-linear structure formation in DE and MG scenarios. We embed the effective field theory of dark energy (EFTofDE) framework into this new numerical pipeline, utilising the $α$-basis parameterisation to provide a versatile, model-agnostic, computational engine. By consolidating diverse scalar and vector-tensor theories---including the normal and self-accelerating Dvali-Gabadadze-Porrati (DGP) models, cubic Galileons (cubic scalar Galileon (csG), cubic vector Galileon (cvG) and generalised cubic covariant Galileon (GCCG)), and generic effective field theory (EFT) parameterisation---into a single "master" Vainshtein equation, this pipeline bypasses the need for model-specific solvers and easily specialises to any particular model. As validations, we perform high-resolution N-body simulations for the normal-branch DGP (nDGP), csG, GCCG, and EFT models, comparing the resulting matter power spectra against dependent and independent codes such as legacy ECOSMOG and HiCOLA, as well as linear theory, and find excellent agreement. EFT-RAMSES provides a robust and versatile computational tool for precision cosmological tests of DE and MG using upcoming cosmological surveys. The code is available for download from the GitHub EFT-RAMSES repository.

Origins of globular clusters (GCs) are linked to the assembly of their host galaxies. We analyze star-cluster populations in two strongly lensed systems that bracket Cosmic Dawn and Cosmic Noon: the Cosmic Gems arc (GEMS) at z=9.625, among the first galaxies, and the Sparkler at z=1.378. New STARRED deconvolution photometry of GEMS provides SEDs for ten unique, doubly imaged cluster candidates, while a homogeneous Bayesian analysis places both populations on a common cosmological timeline. The GEMS clusters formed at $z_{\rm form}\approx 10$--$11$ (median $\simeq10.2$), consistent with halo assembly at or above the atomic-cooling scale. Their photometry requires low metallicities: individual clusters are consistent with $[Z/{\rm H}] \lesssim -1.2$, and the data exclude $[Z/{\rm H}]\geq-0.5$, though they cannot distinguish reliably below $[Z/{\rm H}] \simeq -1.5$. This conclusion is unchanged when using stellar-population models including binary evolution---important for ultraviolet emission at this age---yielding similarly low metallicities, $[Z/{\rm H}]=-2.2$ to $-2.7$. The formal estimate, $[Z/{\rm H}] = -2.3\pm0.3$, is consistent with the Milky Way GC metallicity floor, though its value remains prior-dependent. The Sparkler clusters formed $\sim2.5$ Gyr later, at $z_{\rm form}\approx 2$--$3.5$ in a Cosmic Noon dwarf galaxy, and are more enriched ($[Z/{\rm H}] \approx -0.5$). Comparison with Milky Way GCs places GEMS in an exceptionally early, metal-poor regime and the Sparkler among later, more enriched populations, though neither association uniquely determines an in-situ or ex-situ origin. Closed-box and gas-regulator calculations show both systems are compatible with limited pre-enrichment followed by rapid enrichment and accretion-regulated growth. Together, they probe distinct cluster-forming environments from Cosmic Dawn to Cosmic Noon.

To explore neutrino astronomy at high energies (> 10 PeV), the Radar Echo Telescope for Cosmic Rays (RET-CR) was developed to assess the feasibility of a radar technique for detecting particle cascades in ice, serving as a precursor to the Radar Echo Telescope for Neutrinos (RET-N). The main concept of RET-CR is that, as a high-energy cosmic-ray air-shower core propagates into the high-altitude ice sheet, a dense secondary-particle cascade is created, which is very similar to that of an in-ice high-energy neutrino-induced cascade. At RET-CR, the expected signal consists of three distinct components: radio emission from the in-air particle shower, Askaryan radio emission from the secondary in-ice cascade, and the radar signal itself arising from the reflection of the transmitted radio signal from the ionisation trail of the in-ice secondary cascade. In this work, we present the first combined simulation-based package and study aimed at characterising the combined radio and radar signals at the in-ice receivers at RET-CR. We describe the simulation framework and provide a detailed discussion of the salient features of the radio and radar signals, including their spatial footprints and temporal characteristics, as predicted for the shallow in-ice detectors.

This paper introduces $\tt {\mathcal C}osmo{\mathcal L}attice$ $\tt v2.0$, a major upgrade that substantially broadens the physical scope and computational capabilities of the code. It introduces lattice implementations of scalar fields non-minimally coupled to gravity through $φ^2R$, as well as axion-like fields coupled to Abelian gauge sectors as $φF_{μν}\widetilde F^{μν}$. It also provides new procedures for generating specialized initial conditions, including scaling networks of cosmic defects ($\it e.g.$ strings and domain walls), and fields with arbitrary power spectra. The release also incorporates low-storage Runge-Kutta integrators for non-symplectic systems (suitable $\it e.g.$ for non-minimal scalar kinetic terms as $\mathcal{G}_{ab}\partial_μφ^a\partial^μφ^b$), scalar-field simulations on reduced $(1+1)$- and $(2+1)$-dimensional lattices, new optimized gravitational-wave evolution, more flexible field and energy-density outputs, and GPU support that can accelerate simulations by a factor $\mathcal{O}(10)$ relative to CPU execution. Extensive documentation on the use of the code is provided on https://www.cosmolattice.com

We construct the exterior coupled gravitational and electromagnetic response of a magnetically supported generalized Hayward black hole within a specified nonlinear electrodynamic completion. Both parity sectors reduce to canonical two channel wave systems with explicit potentials and the correct Schwarzschild and effective Reissner--Nordström limits. We compute the quasinormal spectrum, metric and optical characteristics, extremal throat weights, quadrupolar wave conversion, finite bandwidth transfer, and coherent absorption eigenchannels while verifying exterior hyperbolicity and flux conservation. An effective charged operator captures the leading weak core geometry and mode mixing; after its subtraction, the residual hierarchy is consistent with cubic spectral corrections in the primarily electromagnetic branch and quartic corrections in the primarily gravitational branch and principal scattering observables. The fundamental quadrupolar branches become intrinsically linewidth separated near $χ\simeq0.70$, whereas parity splitting remains subleading. Metric and optical characteristic families separate monotonically toward extremality. At $χ=0.9$, positive parity reflected conversion reaches $45.8\%$ and remains $40.8\%$ after moderate bandwidth averaging, while coherent incident combinations yield $98.4\%$ bright and $1.3\%$ dark absorption. These independently evaluated observables provide mutually consistent diagnostics of the same nonlinear electrodynamic operator.

Blue asymmetries (``Blueshifts'') in the C IV 1550A emission line are common in luminous quasars. If they are formed in winds, how much energy, momentum and mass do those winds transport? We address this question by considering how much mass must be supplied through the line-forming region to maintain a given density and ionization state. Using a combination of 1D analytic and 2D numerical models, we find that for blueshifted C IV lines to form in a wind, the wind must have mass outflow rates of $\sim 50 f_V$ times the accretion rate, where $f_V \leq 1$ is the volume filling factor accounting for clumping. Our results therefore disfavour line formation in a smooth disc wind and point towards one of two scenarios: either the wind is clumpy, with required clumping factors suggestively close to those in hot star winds; alternatively, if the mass is instead swept up from the ambient medium, the wind need not be clumpy and MHD and radiative winds can provide the original source of momentum and energy. The power of the outflow depends on the square of the terminal velocity of the flow, $v_\infty$. If the wind is also the BAL outflow, with $v_\infty \sim10,000~{\rm km~s}^{-1}$, the wind power is significant and important for feedback. There are various caveats which moderate our conclusions, motivating i) a better theoretical understanding of wind driving and clump formation physics and ii) improved observational constraints on the physical conditions where the lines are formed.

The solar wind is characterized by turbulence, where a cascade produces intermittent current structures called current sheets (CS) that efficiently dissipate energy into the plasma. These have been studied with in situ spacecraft observations, but single-spacecraft techniques such as the partial variance of increments (PVI) are inherently limited since they lack spatial context. A combined analysis of in situ observations and numerical simulations can provide significant insight into the properties of intermittent structures forming in heliospheric turbulence. Understanding the size and distribution of these structures is crucial in tracing the pathways of energy dissipation and particle energization in space plasma. Using 3D fully kinetic simulations of magnetized turbulence, we identify CS via machine learning and find a complex broken-power-law distribution for the CS widths, where the power-law breaks separate ion-scale CS from electron-scale CS. Electron-scale CS dominate, with widths peaking near $2d_e$. Comparing simulations with MMS data, we test PVI as a CS detector and show it can infer CS scale, though oblique crossings inflate inferred sizes. The prevalence of electron-scale sheets suggests they may contribute to plasma heating in aggregate.

LiteBIRD is a JAXA-led space mission designed to produce all-sky microwave polarization maps. Its primary science goal is to test representative inflationary models by measuring the cosmic microwave background $B$-mode polarization generated by primordial gravitational waves, while also providing new insights into cosmology, particle physics, and astrophysics. The mission concept has been updated following the reformation activities initiated after the Mission Definition Review in 2024. The current concept preserves the central scientific objectives, while simplifying the payload configuration: a single telescope covers 12 frequency bands with band centers spanning 40 to 402~GHz, corresponding to an optical coverage of 34--448~GHz. The telescope is a cross-Dragone reflector with a 500~mm aperture diameter, cooled to approximately 5~K and coupled to transition-edge-sensor bolometer arrays operated at 0.1~K. LiteBIRD will observe from a Lissajous orbit around the Sun--Earth L2 point during a nominal 3-year survey. More specifically, the primary scientific objective is to achieve total uncertainty in the tensor-to-scalar ratio of $δr < 0.002$ (68\% C.L.), including contributions from foreground residuals, statistical uncertainties, instrumental systematics, and margin contingency. The corresponding map-noise requirements are specified separately for the low-, mid-, and high-frequency ranges over the reionization and recombination multipole ranges. This sensitivity makes LiteBIRD unique not only for inflationary science but also for a broad range of scientific investigations probing the history of both the early and late Universe, as well as for astrophysical processes, including Galactic science. This paper summarizes the scientific objectives, updated payload and instrument concepts, observation strategy, and ground segment plans.

This paper investigates how to extract energy from a non-Kerr rotating spacetime with an anomalous quadrupole moment via the magnetic reconnection mechanism. Unlike many other rotating spacetimes, this spacetime possesses closed timelike curves, and the corresponding spacetime regions must be excluded when extracting energy. After introducing the event horizon, ergosphere, and closed timelike curves of this spacetime, we deeply analyze the energy per unit enthalpy at infinity for accelerated and decelerated plasmas, the allowed region for energy extraction, and the power and efficiency of energy extraction. The results show that energy extraction is possible for both positive and negative anomalous quadrupole moments, but a positive and small anomalous quadrupole moment corresponds to higher power and efficiency of energy extraction.

In the early universe, neutrinos undergo many interactions with the particles in the plasma. Key processes are the scattering of neutrinos by free electrons and positrons. In this paper, we derive general expressions for the electron neutrino-electron scattering kernel in isotropic media, analytically simplifying the 5D collision integral to two dimensions. We follow a procedure that is similar to the derivation of the Compton scattering kernel to reduce the angular integrals, yielding a compact analytic expression in terms of elementary functions that can be easily evaluated. We illustrate the properties of this kernel and also compute its first moments analytically, providing insights into the energetics of the redistribution process. For comparison, we consider the photon-electron scattering kernel, highlighting differences and similarities. We then explain how the obtained expressions can also be applied to the $ν_{μ/τ}$-electron and neutrino-positron scattering processes. The results presented here may be useful in the context of Big Bang Nucleosynthesis and were added as an extension to the Compton scattering library CSpack for more general applications.

Deformations of sandwich gravitational waves are considered. Squeezing a wave with pure displacement (DM) parameters to an impulsive wave, the DM property is lost, leaving us with the velocity effect (VM). For each fixed value of the deformation parameter $p$, DM can be restored by further increasing the amplitude which however diverge when $p\to\infty$, and no impulsive wave is obtained.

The gravitational baryogenesis is studied in regularized four dimensional Einstein Gauss Bonnet model with rainbow gravity corrections. This combined framework generates a non vanishing time derivative of the Ricci scalar even during radiation domination era. We derive analytical expressions for the baryon to entropy ratio in both the high curvature and perturbative regimes. The Gauss Bonnet contribution produces nonzero asymmetry precisely at radiation era, where the Einstein Hilbert contribution vanishes. Numerical analysis identifies viable parameter spaces reproducing the observed baryon to entropy ratio, compatible with observations.

Slow magnetoacoustic waves have been observed in the solar corona for decades; yet, existing theories do not fully explain the wide range of observed decay lengths, and measurements from different instruments frequently disagree. We present two events with simultaneous SDO/AIA and Solar Orbiter/EUI-HRIEUV observations of slow waves in sunspot-anchored coronal fan feathers. In Event 1, the LoS are separated by 16.2 degrees, while in Event 2, they are almost parallel. Using time-distance analysis, we identify waves with periods in the 3-minute band and quantify wave decay using the exponential folding length. When LoS are non-parallel, the ratio of decay lengths measured by the two instruments, $λ_\mathrm{ratio} = λ_{\mathrm{AIA}} / λ_{\mathrm{EUI}}$ varies widely, with both $λ_\mathrm{ratio} > 1$ and $λ_\mathrm{ratio} < 1$ observed. However, when the LoS are almost parallel, the decay lengths agree with one another, and $λ_\mathrm{ratio} \approx 1$. These results show that the angle between the LoS and the wave propagation direction is key to determining the apparent decay of slow waves, a factor that has not yet been systematically accounted for. Since statistical studies of decay lengths constrain coronal energy-loss mechanisms, observational effects beyond simple projection must be corrected to reliably infer the underlying physical dissipation processes.

Recent molecular line surveys, particularly toward the starless core TMC-1 CP, have greatly expanded the inventory of interstellar molecules, revealing numerous isomers and even aromatic species. Their diverse formation pathways---from ion-molecule reactions to the possible fragmentation of carbonaceous grains---remain under debate, linking chemistry to the life cycle of the interstellar medium. Simple tracers such as carbon chains and deuterated ions are used to probe the physical conditions and evolutionary state of nearby filaments and cores, as well as in massive infrared dark clouds. Ice chemistry has also entered a new era with JWST: spatial distributions of ices indicate a connection between catastrophic freeze-out, established in the prestellar core L1544, and formation of complex organic molecules. Overall, TMC-1 CP and L1544 are not outliers but representative laboratories of molecular cloud physics and chemistry. Extending these findings across diverse environments, from the Central Molecular Zone to low-metallicity galaxies, is essential for a unified picture of how interstellar chemistry regulates the path from clouds to stars and planets.

The strong deflection limit (SDL) of the deflection angle is well established for general spherically symmetric spacetimes, but a systematic SDL treatment of spin precession has been lacking. We derive the SDL expansion for the spin precession angle of particles propagating along geodesics in static, spherically symmetric, and asymptotically flat spacetimes. The SDL coefficients are obtained, and a simple relation linking the precession angle to the deflection one is established. Applying the formalism to Schwarzschild and Reissner-Nordström (RN) spacetimes, we obtain fully analytic SDL coefficients for the former and perturbative charge corrections to $\mathcal{O}(Q^2)$ for the latter. These results explicitly verify the universal spin-flip of massless particles in backward scattering, which is the underlying mechanism governing the absence of the glory spot. While the spin precession of massless particles is charge-independent, massive particles acquire a non-trivial charge dependence that distinguishes the RN case from Schwarzschild.

Conserved gravitational charges are commonly expressed as surface integrals of the metric perturbation and its first derivatives. We show that, in the usual asymptotically AdS and asymptotically flat settings, the standard charges admit equivalent representatives as fluxes of linearized curvature. The construction uses a divergence-free rank-four tensor whose trace is proportional to the cosmological Einstein tensor. On a maximally symmetric AdS background, it reproduces the known curvature representation of the Abbott-Deser charges. The asymptotically flat construction is not obtained by taking a naive $Λ\rightarrow 0$ limit, since the Killing two-form vanishes for translations. We instead introduce an antisymmetric Poincaré Killing potential. A representative Killing potential adapted to the algebraic Bianchi identity converts the linearized Einstein current into a total divergence and yields a single curvature-flux formula. Its translation sector reproduces the ADM energy--momentum, while in four dimensions its Lorentz sector reproduces the angular momentum and boost/center-of-mass charges under the standard Regge-Teitelboim falloff and parity conditions. The normalization is checked explicitly for Schwarzschild, boosted Schwarzschild, and Kerr data. On non-maximally symmetric Einstein backgrounds, background Weyl curvature generates additional terms, so the maximally symmetric construction does not directly extend to a pure codimension-two curvature-flux formula.

We investigate how well large language models (LLMs) can assist with literature reviews for scientific research. We perform a controlled study of eight expert-conceived research projects across the areas of physics, astrophysics, and cosmology. Each project has a defined background and goal, and human experts and AI prompters are asked to perform identical literature review tasks in parallel. We compare the relevant literature selected by humans with that selected by mid-2025 LLMs (ChatGPT-4o, ChatGPT Deep Research, and Gemini). We find the overlap between human- and AI-selected references to be small ($<$6\%), indicating that AI models do not yet reproduce a competent expert search on their own, though they have the potential to complement literature searches by humans. We then assess the reliability and completeness of AI-generated candidate references, distinguishing two types of hallucination: fabrications (references to nonexistent papers) and metadata mismatches (real papers with one or more incorrect fields). We find that while fabricated references make up 3\% of the AI-generated references, 64\% are real papers with at least one incorrect field (title, author, year, journal, DOI, or link), indicating that the mid-2025 models require systematic verification. However, the performance is significantly improved for the 2026 model ChatGPT Pro 5.5, with a single-project test showing zero fabrication or metadata mismatches.

The infrared-flux excess of stars harbouring Dyson spheres represent one potential technosignature of extraterrestrial intelligence. In a previous Project Hephaistos paper, we highlighted seven M dwarfs within 300 pc with unusual infrared properties that seem to resemble those expected for Dyson spheres. In the present study, we present an analysis of photometric and, in some cases, spectroscopic data on these seven objects, plus three additional objects with similar properties, to further constrain their nature. The stellar parameters, derived from calibrated empirical relationships for M dwarfs, reveal no irregularities with respect to the overall M-dwarf population of main-sequence stars. While the infrared properties of our targets resemble those of circumstellar disks in a transitional state, the objects with spectroscopic data show no signs of youth usually associated with such objects. One of our spectroscopic targets does exhibit weak H$α$ emission, but this is more likely attributed to stellar activity than to the gaseous accretion disk expected for a young star. After this analysis, we still find no clear explanation for the infrared excess of these stars, but note that observations with the JWST and/or the Atacama Large Millimeter/submillimeter Array would be able to probe scenarios in which the infrared excess is due to circumstellar dust emission or an infrared-bright background source that remains undetected at shorter wavelengths. For two of our stars, JWST observations have recently revealed superpositions with very red background galaxies.

The cosmic dipole measured in surveys of cosmologically distant sources consistently exceeds the expectation derived from the cosmic microwave background, posing a significant challenge to the standard $Λ$CDM cosmology. In the era of precision cosmology, quantifying robust tensions is constrained by our ability to model complex, non-linear effects that often result in intractable likelihood functions. In this paper, we present a flexible simulation-based inference (SBI) architecture for measuring the cosmic dipole tension using Neural Ratio Estimators (NREs). We design and train an ensemble of NREs to evaluate the log Bayesian evidence ratio and measure $Nσ$ tension. We validate our approach against nested sampling, demonstrating that it accurately recovers the ground-truth. Under the kinematic interpretation of the dipole, we apply our approach to Planck, the NRAO VLA Sky Survey (NVSS), the Rapid ASKAP Continuum Survey (RACS), and the Wide-field Infrared Survey Explorer catalogue (CatWISE). Here, leveraging SBI, we measure a $\approx5.7σ$ tension between CatWISE and Planck. We demonstrate the extensibility of our approach by applying it to forward-modelled simulations of the CatWISE Eddington bias, revealing a $\approx6.7σ$ tension. The methodology proposed here enables robust tension quantification as we enter the era of LSST, Euclid, and the SKA.

We investigate scalar perturbations of the static loop quantum black bounce (LQBB) spacetime with multipole index $l=1$, focusing on time-domain signals and fundamental quasinormal frequencies (QNFs). The LQBB model provides a unified description of regular black holes (RBHs) and traversable wormholes, governed by the quantum parameter $α$ and the bounce parameter $r_b$. Using the finite difference method, we find no echoes for the displayed RBH configurations with a single-barrier effective potential, whereas clear echoes are produced by the potential well structure in selected traversable wormhole configurations. The QNFs obtained from the Prony method and the direct integration method are in good agreement. In the RBH case, increasing $r_b$ or $α$ leads to a slower decay. In the wormhole case, the QNFs depend non-monotonically on the model parameters, and the emergence of echoes is closely tied to the effective potential profile. These results show that the LQBB spacetime provides a useful framework for studying wave dynamics in RBHs and traversable wormholes, and for clarifying how horizon and throat structures affect ringdown and echoes.

Hot subdwarf stars (sdO/Bs) are widely considered to be products of binary evolution. A significant fraction of them are found in long-period or wide binaries ($P>500$ d) with main sequence (MS) companions, likely resulting from a stable mass transfer episode where the MS companion stripped the hydrogen envelope of the sdO/B progenitor. Consequently, wide sdO/B binaries represent a key population in our pursuit of understanding stable mass transfer. They exhibit a modest range of orbital periods and eccentricities as revealed by long-term spectroscopic campaigns, though the component masses are not well constrained. In this Letter, we present the first long-baseline interferometry campaign to observe wide sdO/B + MS binaries and take the first step toward determining their 3-dimensional (3D) orbits and model-independent component masses. We target six composite sdO/B + MS systems with VLTI/GRAVITY and spatially resolve all of them. The projected physical separations range between $1-3$ au, with uncertainties between $1-8$%. When combined with complementary information from spectroscopic or astrometric observations, our precise measurements will be crucial to constrain 3D orbits for these systems. Additionally, we also identify a potential third component in BD+10 2357, although additional data will be necessary for confirmation. In light of continued spectroscopic monitoring and the imminent Gaia Data Release 4, we strongly encourage expanding the interferometric sample presented here to establish new, precise orbital and mass constraints for this key population of binary interaction products.

The detection of magnesium sulphide (MgS) and sodium sulphide (NaS) towards the Galactic Center molecular cloud G+0.693 constitutes the first detection of metal sulphides in the interstellar medium (ISM). However, there is scarce information about the key reactions (either in the gas phase or on grains) involved in their formation. In this paper, we model the chemistry of MgS simulating the passage of a low-velocity shock to recover the abundances recently measured towards G+0.693. Through this chemical modelling, we analyse the dominant reactions involved in the formation and destruction of this molecule, their associated chemical time-scales, and the depletion factor needed to recover the observed abundances. We build the initial chemical network of MgS by using SiS as a proxy for this metal sulphide, and we investigate the exothermicity of these and additional, uniquely proposed reactions through quantum chemical computations. We run a three-phase model (initial translucent cloud, cloud collapse phase and shock interaction stage) that mimics the evolution and physical conditions of G+0.693. Our results show that a depletion factor of 1000 is required for elemental Mg to recover the observed abundances of MgS. This implies that potentially more than 99.9% of Mg is locked in dust grains. The dominant reaction leading to the formation of MgS is the neutral-neutral reaction between MgH and S in the gas phase. This work represents the first analysis of the chemistry of the metal-sulphide MgS and suggests that Mg is largely incorporated into dust grains, most likely in the form of silicates. However, additional laboratory and/or theoretical studies of the key MgS formation reactions are essential to obtain more reliable constraints. Future missions, such as PRIMA, will provide insights into the amount of metal-sulphides locked into interstellar dust grains.

The acceleration and heating of the fast solar wind remain long-standing challenges in space physics. One type of leading theoretical models requires high-frequency magnetohydrodynamic (MHD) waves to transport and dissipate sufficient energy in the corona. However, such high-frequency waves with energetically significant amplitudes have never been unambiguously observed, leaving a key gap between theories and observations. Using high-cadence, high-resolution extreme-ultraviolet imaging from Solar Orbiter's Extreme Ultraviolet Imager, we identify a previously hidden population of high-frequency MHD waves in coronal plumes of the solar polar region. An analysis of the detected propagating kink waves shows that over one-third have periods shorter than 100 s, a population largely undetected by earlier instruments. Power spectral analysis demonstrates that these high-frequency waves carry substantial energy flux, which are significantly underestimated in lower-cadence data. These results suggest that high-frequency MHD waves may contribute importantly to the energy budget of the solar polar corona and could play a role in solar wind acceleration, highlighting the value of high-resolution observations for probing energy transport in magnetized space and astrophysical plasmas.

This study focuses on the radial evolution of the solar wind proton adiabatic invariants and temperature anisotropies in the inner heliosphere. More specifically, we study in-situ measurements provided by the Parker Solar Probe, between 0.05 au and 0.25 au from the Sun, and Solar Orbiter spacecraft between 0.3 au and 1 au. Throughout the studied range of radial distances, we observe a significant average heating in the direction perpendicular to the local magnetic field for both fast and slow solar wind populations. On the other hand, there is no clear deviation from adiabaticity in the parallel direction regardless of the wind speed. The perpendicular heating is enough to significantly reduce the generation of the temperature anisotropy expected from a double adiabatic evolution. Despite the heating, an important portion of the solar wind (especially the slower wind streams) develops substantial anisotropies with higher parallel temperatures, which eventually become constrained by kinetic firehose instabilities.

Recent analysis of Parker Solar Probe (PSP) and Solar Orbiter data indicates that fluctuations energy is transferred to the bulk flow in fast streams of the solar wind at heliocentric distances between 15 and 120 Rsun. To gain insight into this process, we analyze data collected during the inbound orbit of PSP in Encounter 10, when it is in approximate corotation with the Sun and an accelerating stream is detected between 25 and 45 Rsun. The geometry of the flow indicates that a neighboring very fast streams is colliding with the corotating stream, causing large-scale magnetic field distortion, density enhancement, and acceleration. However, also deposition of fluctuations' energy can heat and do work on the solar wind plasma, resulting in a radial acceleration. We evaluate the energy lost by fluctuations via radial variation of conserved quantities in the corotating stream and find that it is almost equally partitioned into heating and work. While the heating is marginally consistent with the non-adiabatic decrease of proton temperature, the work exerted on the wind is insufficient to account for the measured solar wind acceleration. Although limited to this event, observations suggest that shear interaction is capable of accelerating slower streams within relatively short distances from the Sun, possibly leaving its imprint as large-scale density and magnetic fluctuations.

In recent years, citizen science became an integral part of astronomy. Numerous projects contribute to important studies by involving large communities. While these are getting quite some attention, there are also individual efforts, which are nevertheless very valuable. Here, we report on results of a search for compact optical emission line nebulae, which are signposts of both young and evolved stars. The increased brightness in red photometric bands due to the contribution of shock-excited emission lines has been used as a tracer when examining optical broadband surveys. With the help of public databases, we identified and characterized associated sources if possible. Most of them are young stellar objects (YSOs).

We investigate how well large language models (LLMs) can assist scientific project planning and proposal evaluation. One-page project plans were independently generated for eight expert-conceived research projects in physics, astrophysics, and cosmology by human researchers and three contemporary LLMs (ChatGPT, Claude, and DeepSeek; mid-2025 models, used with their default tool access). The resulting 32 proposals were blindly evaluated by four human reviewers and two newer frontier LLMs (Claude Opus 4.8 and ChatGPT Pro 5.5) using a four-aspect evaluation rubric. Reviewers were also asked to identify whether each proposal was written by a human or an AI. Human reviewers rated human- and AI-written proposals similarly overall, whereas both AI reviewers scored AI-written proposals about one point higher (on a five-point scale) than human-written proposals. Human reviewers correctly identified human- and AI-written proposals 72% and 79% of the time, respectively, while both AI reviewers correctly classified all 32 proposals (100%). These results suggest that current LLMs can produce project plans comparable to human-written ones in the eyes of human reviewers, but that AI reviewers show a systematic preference for AI-generated proposals. Our results suggest caution when deploying LLMs widely in proposal preparation and evaluation.

The observed dust abundance in the early Universe significantly exceeds the predictions of models assuming its efficient destruction at supernova shock wave fronts. We investigate the effect of dust on gas cooling behind the shock wave front, taking into account both dust cooling and thermal sputtering of dust grains for various interstellar dust models. Isochoric cooling of a gas element is considered for various initial temperatures (from $3\cdot 10^{5}$ K to $3\cdot 10^{7}$ K) and metallicities (from $10^{-2}$ Z$_{\odot}$ to 2 Z$_{\odot}$). It is shown that at metallicities below 0.1 Z$_{\odot}$, the effect of dust on gas cooling is negligible. The abundance of small grains in some models significantly accelerates cooling at temperatures below $10^{6}$ K, whereas large grains dominate cooling at high temperatures ($> 3\cdot 10^{6}$ K). For an initial temperature $T_{g,0} > 3\cdot 10^{6}$ K, less than 10% of the dust mass survives for some models of the initial size distribution. The maximum survival rate (up to 20% at $T_{g,0} = 3\cdot 10^{6}$ K and solar metallicity) is achieved for the model with the shallowest grain size distribution. The role of gas inhomogeneities is discussed: dust stripping from clouds by a shock wave can both decrease the cloud lifetime and contribute to the creation of dust tails, where the cooling of hot gas is accelerated, thereby increasing the dust survival rate.

Mapping the subsurface structure and flow field of sunspots has been a challenging task for helioseismology. In this work, we investigate the propagation of acoustic waves in a sunspot in NOAA active region 11312 using time-distance helioseismology. Travel times of waves traveling into and out of the sunspot are measured as functions of travel distance and azimuthal angle relative to the local radial direction. The same time-distance analysis is also applied to a simulated data based on a magnetohydrostatic (MHS) model of sunspot, and forward modeling of travel times is performed using ray tracing based on both the MHS sunspot model and a magnetohydrodynamic (MHD) simulation. We find that both ingoing (traveling from the quiet area into the sunspot) and outgoing waves (traveling from the sunspot into the quiet area) have shorter travel times than in the quiet Sun, with travel-time reductions of up to 40 s. The magnitude of the mean time shift is largest for waves traveling along the radial direction at small travel distances. A clear asymmetry is detected between ingoing and outgoing waves: outgoing waves generally exhibit shorter travel times. This asymmetry is strongest for radial direction and small travel distances, with differences exceeding 1 min for 3.5 mHz and 4.5 mHz waves. From the results of both observations and models, our analysis indicates that the overall reduction in travel time could be primarily caused by the combined effects of Wilson depression, magnetic field, and wave-speed perturbations, while the ingoing-outgoing asymmetry could be partly attributable to subsurface flows. Although the forward-modeling results reproduce several qualitative features of the observations, quantitative discrepancies remain, highlighting limitations of current sunspot models and ray-theoretical approximations.

Secondary bias is the dependence of halo clustering on properties beyond halo mass. Using the $z=0$ TNG300-1-Dark simulation, we study anisotropic secondary bias (ASB): the variation of secondary bias with direction relative to the halo major axis. We first use ordinary, orientation-averaged secondary bias (OSB) as a baseline to compare three environmental manifestations: halo-environment alignment, outer matter anisotropy, and tidal anisotropy. Matching tidal anisotropy suppresses much of the OSB, whereas matching halo-environment alignment or outer matter anisotropy does not. ASB behaves differently. It is weak for formation time, concentration, and triaxiality, but strong for both spin definitions and minor-to-major axis ratio; slowly rotating and more elongated haloes are more strongly aligned with filamentary structure. Matching halo-environment alignment substantially reduces the spin- and shape-dependent ASB signals, whereas matching tidal anisotropy or the outer matter axis ratio leaves them largely intact. Halo definition has little impact on ASB, yet strongly affects low-mass spin bias: including unbound particles can move dense-environment haloes with low bound-particle spin into the high all-particle-spin sample. These results clarify which clustering signals are associated with halo-environment alignment, matter anisotropy, or tidal anisotropy, and which are sensitive to halo definition.

The morphology of the cosmic web formed by the late-time matter distribution encodes cosmological information beyond that contained in standard two-point statistics. Marked power spectra provide a computationally efficient framework to access this higher-order information, by studying the two-point statistics of the density field ``marked'' (i.e. weighted) by a function of its local environmental density. In this work we explore the potential of marks that are sensitive to the morphology of this local environment, rather than simply its density. We study a broad range of such marks, considering mark functions based on the smoothed density, tidal shear amplitude, local degree of isotropy and filamentarity, Gaussian transformations of these quantities and a local fractal dimension estimator. We quantify the merit of different marks in terms of their constraints on key cosmological parameters, including the matter abundance $Ω_m$, the amplitude of fluctuations $σ_8$, and the mass of neutrinos $M_ν$. We have found that density-dependent marks continue to provide the largest improvements over the standard power spectrum, while morphology-based marks yield more modest improvements on their own. Nevertheless, combining density- and morphology-based marks consistently enhances cosmological constraints beyond what either class achieves separately, demonstrating that they probe complementary aspects of the underlying matter distribution. These results provide a systematic assessment of morphology-based marked statistics and explore which geometric properties of the cosmic web contribute most effectively to cosmological parameter inference. They also establish a physically motivated framework for future investigations of optimal marks and their perturbative connection to higher-order correlation functions.

In this paper we propose that spacetime is an emergent fractal geometry generated by the entanglement structure of an underlying quantum information network. Indeed, it is developed a framework in which spacetime, quantum mechanics, and gravity emerge from the entanglement structure of a universal quantum state. Geometry is defined by an information-theoretic distance $d_{ij}=-\ell_0\log(I_{ij}/I_0)$ on an entanglement graph, producing a scale-dependent, fractal spacetime whose effective dimension flows toward $D\to 2$ near the Planck scale. In this fractal geometry, nondifferentiable trajectories lead to stochastic geodesics and a complex covariant derivative, from which the Schrödinger equation follows as an emergent dynamical law. Gravity arises from the time dependence of the entanglement-induced metric, yielding Einstein gravity in the macroscopic limit and fractal corrections encoded in a generalized field equation $G_{μν}=8πG(T_{μν}+αE_{μν}+βF_{μν})$. The resulting \emph{Fractal Entanglement Quantum Gravity} (FEQG) framework predicts dimensional reduction, modified gravitational potentials, and possible deviations from standard quantum mechanics at ultrashort scales, offering a unified informational origin for quantum theory and gravitation.

Composite dynamical dark energy (DDE) has recently been explored as an efficient way to help cure cosmological tensions through the so-called $w$XCDM model {Gomez-Valent:2024tdb,Gomez-Valent:2024ejh}, a toy-model version of the $Λ$XCDM model {Grande:2006nn}. The latter is a composite running vacuum model (RVM) that involves a DE component $X$ (`cosmon') of generic nature. We compute the effective equation of state of $Λ$XCDM and use state-of-the-art techniques to fit this model to two standard sets of cosmological data, one involving SNIa from Pantheon$+$ and the other SNIa from DES-Dovekie, in addition to BAO data from DESI DR2 and the CMB data from Planck PR4. We do not use large scale structure formation data for this analysis nor the SH0ES calibration of $H_0$. We find that $Λ$XCDM naturally performs the crossing of the phantom divide as observed by DESI near $z\simeq 0.4$ using the $w_0w_a$CDM parameterization, a feature well favored by existing model-agnostic analyzes of the same data {Gonzalez-Fuentes:2025lei,Gonzalez-Fuentes:2026rgu}. It turns out that the cosmon $X$ behaves as `phantom matter' (PM) near the present, which in contrast to usual phantom DE satisfies the strong energy condition (as ordinary matter) and furnishes positive pressure ($P_X>-ρ_X>0$) at the expense of negative energy density ($ρ_X<0$). $Λ$XCDM provides a better fit than $w_0w_a$CDM and, as a bonus, alleviates the cosmic coincidence problem. Given that PM appears in stringy versions of the RVM, the $Λ$XCDM appears to be a composite DDE model with a good chance of explaining the crossing of the phantom divide from first principles, therefore providing theoretical support to the DESI observations inferred from generic parameterizations of the DE.

We present CLASSIER-DDM, an extension of the Boltzmann solver CLASSIER that implements the decaying dark matter (DDM) model via its integral-equation approach. The code handles generic two-body decays of a dark matter particle into two lighter decay products with arbitrary masses, naturally encompassing both massless (dark radiation) and massive (warm) decay products, with their perturbations evaluated via integral equations solved iteratively. We describe the numerical implementation in detail, including the background evolution, the iterative perturbation evolution, and a small-scale analytic approximation. A modest number of iterations is sufficient to achieve sub-$0.1\%$ convergence in the matter power spectrum and the CMB lensing power spectrum across the observationally relevant parameter space. We find that a hundred momentum bins for the decay product perturbations are sufficient to achieve $\mathcal{O}(0.1\%)$ accuracy in the matter power spectrum today up to $k \sim 3\,{\rm Mpc}^{-1}$. The code achieves $\mathcal{O}(1\,{\rm min})$ runtimes per evaluation, requiring neither a Boltzmann hierarchy nor any fluid approximation, making parameter estimation with the DDM model numerically tractable. We also discuss the impact of DDM on cosmological observables, focusing on the case of two massive decay products. This work further establishes the integral-equation approach as a versatile and efficient framework for modeling non-cold relics in cosmological perturbation theory.

Recent studies have suggested a mismatch of up to 0.20 dex between iron abundances derived from Fe I and FeH lines in the H-band spectra of M dwarfs, and in this work we investigate the nature of this possible offset. We analyze near-infrared H-band APOGEE spectra of stars in 18 binaries composed of a G-dwarf primary and an M-dwarf secondary, together with four M-dwarf stars having measured angular diameters from the literature, and six M-dwarf members of the Hyades and Coma Berenices open clusters. These three families of benchmarks were used to evaluate the FeH line list and check for possible systematic uncertainties in the FeH $gf$-values. Our tests used 1-D LTE plane-parallel model atmospheres, a radiative transfer code, and the baseline APOGEE spectral line list to derive metallicities for the binary G-dwarf primaries using Fe I lines, while stellar parameters and metallicities for the M dwarfs used both FeH and Fe I lines. The mean metallicity obtained for the Hyades M-dwarfs was $\langle$[Fe/H]$\rangle$=+0.08$\pm$0.04, and for Coma Berenices $\langle$[Fe/H]$\rangle$=+0.02$\pm$0.08. The metallicities of the G- and M-dwarfs in binary systems showed excellent agreement (0.06 dex), and the mean metallicities for the open clusters were also consistent with literature values from high-resolution optical analyses. We investigated the consistency between the spectroscopic and interferometric $T_{\rm eff}$ scales, finding agreement within the uncertainties. Forcing full agreement between the spectroscopic and interferometric $T_{\rm eff}$ scales resulted in a poorer match for the metallicities in the binaries and the open clusters. We conclude that the best overall concordance is obtained when no adjustments are made to the FeH $gf$-values, which are based on the Hargreaves et al. (2010) line list.

We study the free Maxwell field on the planar patch of four-dimensional de Sitter spacetime ($dS_4$). We review its bulk canonical quantization in the Bunch-Davies vacuum, and we give a representation-theoretic viewpoint by studying the transformation properties of single-particle states under infinitesimal dS transformations. By taking the late-time limit, we identify two late-time operators with scaling dimensions $Δ=1$ (leading) and $Δ=2$ (subleading). We introduce CFT-inspired inner products invariant under the dS group ($SO(4,1)$) for states created by late-time operators acting on the Bunch-Davies vacuum. We explain how the unitary discrete series representations of $SO(4,1)$ associated with the photon are furnished by both operators, in contrast with the Maxwell field on $AdS$ where the $Δ=1$ operator corresponds to a non-normalizable mode. We also explain how the corresponding discrete series representations of $SO(4,1)$ split into a direct sum of representations corresponding to two helicities $+1$ and $-1$. This is achieved by taking advantage of the dS invariance of the self-dual and anti-self-dual sectors of the photon field strength. In our outlook, we draw inspiration from a recent proposal for the microscopic description of $dS_4$ higher-spin gravity where conformal gauge fields in 3 dimensions play a central role, and we investigate a possible connection of the $Δ=1$ late-time operator with a conformal spin-1 gauge field in 3 dimensions.

Bright-rimmed clouds (BRCs) are valuable laboratories for investigating how ionizing radiation from massive stars reshapes molecular clouds and influences star formation. We present a kinematic and dynamical study of the BRC SFO 25 using archival JCMT-HARP observations of the $^{12}$CO, $^{13}$CO, and C$^{18}$O ($J = 3-2$) transitions at an angular resolution of about 14-15 arcsec (0.051-0.054 pc). Gaia parallaxes of young stellar objects associated with the cloud yield a revised distance placing SFO 25 behind the ionizing O7V star HD 47839, implying that ultraviolet radiation can directly affect both the head and tail. The molecular gas exhibits a pronounced head-tail velocity gradient, with the tail systematically redshifted relative to the head, inconsistent with the expectations of classical radiation-driven implosion (RDI) and suggestive of an evolved phase dominated by radiative dispersal and photoevaporation. The head is moderately denser than the tail, while a compact C$^{18}$O clump associated with IRAS 06382+1017 reaches densities of $10^4~\mathrm{cm}^{-3}$. Virial and energy analyses indicate that the head, tail, and dense clump are gravitationally unbound, with kinetic energy exceeding both the gravitational binding energy and the external ionized gas pressure. Class II young stellar object candidates identified in the tail demonstrate that star formation is not confined to the dense head. Although RDI may have triggered earlier star formation in the head, it cannot readily explain the activity observed in the tail, pointing to a more complex evolutionary history than predicted by the classical RDI scenario.

We study the evolution of superconducting cosmic-string networks in a $U(1)_{\rm local}\times U(1)_{\rm global}$ field-theoretic model using three-dimensional lattice field simulations in an expanding universe. The scalar field charged under $U(1)_{\rm local}$ forms cosmic strings, while the scalar field associated with $U(1)_{\rm global}$ acts as a current carrier and condenses in their vicinity. We investigate the evolution of the string network for several values of the coupling constant between the string-forming and current-carrier fields and estimate the gravitational-wave power spectrum sourced by the resulting superconducting cosmic-string network. We find that the spectral shape depends on the coupling constant: as the interaction strength increases, the spectrum is suppressed on small scales. This feature may be probed by future high-frequency gravitational-wave observations.

In this work, we revisit the generalized emergent dark energy model by confronting it with DESI DR2 baryon acoustic oscillation measurements, in combination with joint CMB data from ACT, SPT, and Planck, as well as Type Ia supernova samples including Pantheon$^+$, DES-Dovekie, and Union3. We find that the GEDE model remains compatible with the $Λ$CDM paradigm, with no statistically significant preference for deviations when all datasets are combined. In particular, the key model parameter $Δ$ is consistent with the $Λ$CDM value $Δ= 0$ within $2σ$ once SNe Ia data are included. Despite this overall agreement, the GEDE model does not exhibit the phantom crossing suggested by DESI DR2. Instead, the evolution of the dark energy equation of state $w(z)$ indicates that the model behaves either as a full phantom ($w < -1$) or quintessence ($w > -1$), depending on the dataset combination, without a clear transition across $w = -1$. When Pantheon$^+$ data are included, the model converges closely to $Λ$CDM with $w \simeq -1$. The GEDE model does not alleviate the existing cosmological tensions. The inferred values of $H_0$ remain in the range $67.9$-$69.8\ \mathrm{km,s^{-1},Mpc^{-1}}$, while the sound horizon $r_d$ and clustering parameter $S_8$ remain consistent with $Λ$CDM, failing to resolve the $H_0$ and $S_8$ tensions. Finally, both Gaussian significance levels ($<2σ$) and Bayesian evidence ($\ln B_{i,j} < 1$) indicate no statistically significant preference for GEDE over $Λ$CDM. We conclude that, although DESI DR2 hints at dynamical dark energy, the GEDE model remains observationally indistinguishable from $Λ$CDM and does not support the Quintom-B-type behavior suggested by DESI DR2.

The high-redshift Ly$α$ forest provides one of the most sensitive probes of the final stages of reionization, but its interpretation can depend on how the ionizing sources are modelled. We test the robustness of Ly$α$ forest-inferred reionization histories using Meraxes, a semi-analytic model of galaxy formation and reionization applied to a cosmological volume of $(210h^{-1}{\rm cMpc})^3$ with merger trees augmented down to the atomic-cooling threshold. We construct a suite of source models in which the galaxy escape fraction, $f_{\rm esc}^{\rm gal}$, is parameterized as a function of halo mass, stellar mass, star formation rate, specific star formation rate, or star-forming disc surface density. We also consider models in which accreting blackholes contribute ionizing photons, or dense circumgalactic gas further attenuates the escape of ionizing photons. Each model is calibrated to the observed distribution of Ly$α$ effective optical depths from XQR-30+. These prescriptions redistribute the escaping photon budget across halo mass and UV luminosity, introduce scatter in $f_{\rm esc}^{\rm gal}$ at fixed halo mass, and allow modest variation in the early evolution of reionization. Nevertheless, all viable calibrated models recover a late and extended EoR, with the midpoint occurring at $z\sim6.2$--6.9 and the final stages at $z\sim5.36$--5.57. Our results indicate that the late reionization history inferred from Ly$α$ forest is robust to physically motivated scatter in the galaxy--halo connection, modest AGN contributions, and phenomenological CGM attenuation.

The investigation of possible quantum-gravity effects in cosmology is of considerable interest, especially when such effects can be tested against observations of the late-time expansion. In the present work we study a quadratic generalized-uncertainty-principle (GUP) deformation of the FLRW minisuperspace Poisson algebra. At first order in the deformation parameter, the construction modifies the Friedmann equation and hence the homogeneous expansion history. Since it does not determine a unique perturbation sector, we restrict the analysis to background observables, using 31 cosmic-chronometer measurements, the uncalibrated 1580-object Pantheon$+$ Hubble-flow sample, and the 13-component DESI DR2 baryon-acoustic-oscillation likelihood, while treating the sound horizon as a nuisance parameter. We compare the resulting cosmology with flat \LCDM{} and with the Chevallier--Polarski--Linder parametrization. For the baseline normalization we obtain $\betastar=-0.086^{+0.040}_{-0.032}$ at $68\%$ credibility and $-0.142<\betastar<0.005$ at $95\%$ credibility.

The evolution of protoplanetary disks is regulated by accretion onto the central star and mass loss through jets and winds. While atomic and ionized outflows are commonly observed, molecular winds in evolved Class II disks remain rarely detected. We characterize the spatial, thermal, kinematic, and dynamical properties of molecular hydrogen (H$_2$) emission from the nearly edge-on Class II disk HV Tau C and assess the impact of its molecular wind. We also constrain accretion using H I recombination lines detected in the same mid-infrared spectrum. Using JWST/MIRI-MRS data from the MINDS Cycle 1 GTO program, we analyze spatially resolved pure-rotational H$_2$ emission. Rotational and position-velocity diagrams constrain excitation and kinematics, from which we estimate wind properties. We detect extended H$_2$ emission tracing a wide-angled, biconical molecular wind extending beyond the near-infrared scattered-light disk, ALMA 887 $μ$m dust continuum, and compact $^{12}$CO ($J=3$-$2$) gas disk. The H$_2$ rotational diagram requires warm ($\sim$600K) and hot ($\sim$2000K) components, similar to those in younger protostars. The gas shows outward motions of a few tens of km s$^{-1}$ and dynamical timescales of tens to hundreds of years. The inferred mass-loss rate is $\sim10^{-8}$ M$_\odot$ yr$^{-1}$, while accretion rates derived from H I lines are $10^{-10}$-$10^{-8}$ M$_\odot$ yr$^{-1}$. The accretion rate may be underestimated because of the edge-on geometry. Our results show that wide-angled molecular H$_2$ winds can persist into the Class II phase, with outflow rates comparable to some protostellar systems, suggesting that such winds may remain important for angular momentum removal, disk evolution, and dispersal. (Abstract modified; see the paper for the full version.)

General Relativistic Entropic Acceleration (GREA) attributes the late-time acceleration of the Universe to the entropy growth of the causal cosmological horizon, without a cosmological constant, with a phenomenology fixed by the single $\mathcal{O}(1)$ parameter $α$. The model has so far been confronted with data only at the background level. We present its first implementation within an Einstein-Boltzmann solver: the GREA background is integrated directly into CLASS, while the entropic component is evolved as an effective fluid regulated by the parametrized-post-Friedmann scheme, giving access to the full CMB and matter power spectra. A Markov-chain Monte Carlo analysis with COBAYA against the full primary-CMB likelihoods, DESI DR2 BAO and Type Ia supernovae constrains the coupling $α\sim 1$, in excellent agreement with the theoretical prediction, with a fit matching $Λ$CDM to within $|Δχ^2| \lesssim 6$ despite the addition of a single free parameter. The equation of state inferred from the data agrees with binned, model-independent reconstructions and exhibits a second crossing of the phantom divide at $z \simeq 2$, a distinctive prediction of the thermodynamic dynamics rather than of an imposed parametrization.

The Unruh effect predicts that an accelerating observer perceives the Minkowski vacuum as a thermal bath, yet direct detection remains experimentally inaccessible. Its timelike counterpart, arising from the entanglement of massless fields between the future and past light cones, offers a more feasible route but requires a detector whose transition frequency follows a specific conformal-time scaling. We propose and analyze a practical implementation of such a detector using superconducting fluxonium circuits, which naturally provide two quasi-degenerate ground states and a tunable excited state, forming an effective $Λ$-system. By modulating the excited-state transition frequency in Minkowski time, the detector accumulates a geometric phase associated with the timelike Unruh effect. Open-system simulations predict $\sim 10\%$ shift in the ground-state population within $530$ ns, representing a three-order-of-magnitude sensitivity enhancement over two-level Unruh-DeWitt detectors. These results establish a realistic quantum-circuit platform for experimentally probing the timelike Unruh effect and, more broadly, for testing fundamental nature of quantum fields using engineered quantum systems.

The influence of relativistic motion on quantum entanglement is commonly attributed to acceleration-induced thermal noise. Here we show that, for asymmetric multipartite states, the topology of entanglement can become equally important. Considering a three-qubit Star state in the Unruh-DeWitt detector framework, we compare two inequivalent acceleration configurations in which either the central or a peripheral qubit undergoes uniform acceleration. We demonstrate that these physically equivalent accelerations lead to qualitatively different entanglement dynamics: acceleration of a peripheral qubit induces a revival of one-tangle that is absent when the central qubit accelerates, whereas genuine tripartite entanglement decays monotonically but with markedly different robustness. Our results uncover a topology-dependent mechanism for relativistic entanglement degradation, showing that the response of multipartite quantum correlations is determined jointly by Unruh thermalization and the structural role of the accelerated subsystem. This work identifies asymmetric quantum networks as a distinct platform for controlling relativistic quantum resources.

We study the island formula and Page curve for the asymptotically flat eternal and quasi-stationary evaporating black hole solutions within the dimensionally reduced Einstein-Hilbert (DREH) model. In this model, the four-dimensional Einstein-Hilbert action reduces to a two-dimensional dilaton gravity, on top of which the quantum corrections can be incorporated via the Polyakov-Liouville (PL) action for a two-dimensional conformal field theory with a large central charge $c$. This gravity model arises from the s-wave approximation of four-dimensional Einstein-Hilbert gravity and provides a fully gravitational setting in which we study the islands, i.e., we will not require a non-gravitational bath region to collect the radiation, instead it lives in the black hole spacetime itself. The fine-grained entropy of Hawking radiation in the eternal and evaporating black holes within the DREH model was derived using the island rule in \cite{djordjevic2022eternal, djordevic2025evaporating}. The island rule is based on the replica method using the Euclidean gravitational path integral. In this work, we complement the Euclidean approach by providing a Lorentzian prescription for the generalized entropy $S_{\text{gen}}$, in the island formula without invoking the replica trick to compute $S_{\text{gen}}$. The generalized entropy is shown to coincide with Wald-like Noether charge of the combined DREH-PL action. Using this generalized entropy, we determine the quantum extremal surface, the Page time, and the Page curve for the eternal and the evaporating black hole. We conclude with a discussion of the possible extension to the full four-dimensional geometry incorporating vacuum polarization corrections.

Limb darkening, the decrease in stellar intensity from the disk center to the limb, encodes the temperature structure and opacity of stellar atmospheres. Direct spatially resolved measurements of this center-to-limb variation remain scarce, especially in the near-infrared. We present interferometric limb-darkening measurements for 31 stars observed simultaneously in the $H$ and $K$ bands with the CHARA Array. The sample spans spectral types F--M and luminosity classes IV--I. The targets are well resolved in $H$ and, for most targets, also in $K$. This coverage constrains the visibility curvature associated with limb darkening in joint $H+K$ fits. We fit the combined $H{+}K$ squared visibilities with four analytic limb-darkening laws and compare the resulting coefficients with bandpass-matched predictions from five stellar-atmosphere grids (Kurucz, MPS1, MPS2, Stagger, and spherical SATLAS, with reported coefficients placed on the Rosseland-radius convention) spanning one-dimensional plane-parallel, three-dimensional radiation--hydrodynamic, and spherical low-gravity models. The associated limb-darkened angular diameters are measured with median formal precisions of $\simeq 0.2$--0.3\%. The CHARA results show expected weaker limb darkening at longer wavelengths and also with increasing $T_{\rm eff}$. The clearest discrepancy with the atmosphere grids is in the wavelength dependence: the median fractional decrease in the power-law coefficient from $H$ to $K$ is $\simeq 39\%$ in the CHARA sample, compared with only $\simeq 17$--$22\%$ with model predictions. Relative to the MPS2 comparison, the empirical coefficients are higher by $\simeq 21\%$ in $H$ and lower by $\simeq 5\%$ in $K$. These results provide multi-band interferometric limb darkening as a near-infrared benchmark for stellar-atmosphere models.

We generalize the notion of quantum reference frames (QRFs) to cases where the frame does not necessarily correspond to a tensor factor subsystem, but to a covariant quantum instrument. This unlocks a variety of physical applications: "frames of labeling" for indistinguishable particles, suggesting explanations for the symmetrization postulate and the absence of parastatistics, and yielding a transparent description of the entanglement of bosons and fermions; and relational clocks reproducing the Schrödinger equation exactly even when all subsystems are interacting or when there are frequency superselection sectors. Our work generalizes the perspective-neutral approach to QRFs pioneered by Höhn and co-authors, which we reconstruct from a simple operational scenario. We give a resource-theoretic grounding of this framework, and show how the notion of completely covariant operations explains the relevance of the charge-zero sector and the pure-state transformation behavior across perspectives. This also suggests operational clarifications of some aspects of constraint quantization, e.g. of the meaning of constraint equations such as $C|ψ\rangle=0$. Some of our results, such as our generalization of relationalization maps to instruments, apply more broadly to other QRF frameworks too, and they contribute to bridging the gap between operational quantum information theory and the internal QRF research program.

In this paper, we present the 1-loop calculation of the three-point function $\langle TJJ \rangle$ of the stress-energy tensor and two insertions of $SO(3)$ global currents, using a 3d toy model for holographic cosmology. By applying the holographic dictionary that relates these QFT $n$-point functions to cosmological correlators, together with the $Sl(2,\mathbb{Z})$ duality that maps the electric Noether current to a magnetic vortex current dual to cosmological magnetic monopoles, we relate the $\langle TJJ \rangle$ correlator to the cross-correlations between metric perturbations and the bulk magnetic monopole field, specifically mapping to the non-Gaussianities $\langle ξ\tilde{A} \tilde{A} \rangle$ and $\langle γ\tilde{A} \tilde{A} \rangle$. We calculate the semi-local contact terms necessary to achieve the exact factorization of the cosmological correlators in the squeezed limit, $p_1 \to 0$. Finally, we evaluate the effective non-linear parameters, showing that the scalar-monopole cross-correlation vanishes at leading order, $f_{NL}^{ξ\tilde{A} \tilde{A}} = 0$, while the tensor-monopole cross-correlation yields a non-zero $f_{NL}^{γ\tilde A\tilde A}$. These results respect the expected amplitude hierarchy of the non-Gaussian correlators, while pointing at new directions in which holographic cosmology can be tested experimentally.

We investigate the two-dimensional conformal field theory (2D CFT) dual of the four-dimensional Kerr-MOG (Kerr-modified gravity) black hole using three complementary approaches: (i) black hole thermodynamics, (ii) monodromy analysis, and (iii) the soft-hair formalism. From these independent methods, we derive consistent expressions for the left- and right-moving temperatures and the central charge of the dual CFT. Finally, we derive the entropy product using these approaches. We show that the product is not universal as well as not quantized. We further explore the hidden conformal symmetry of the non-extremal Kerr-MOG black hole by analyzing the near-region dynamics of a massless scalar field. The resulting Kerr-MOG/CFT correspondence identifies the near-region geometry with a two-dimensional CFT characterized by the temperatures ($T_{L}, T_{R}$) derived in Sec. 3. Moreover, using the Cardy formula, we reproduce the microscopic entropy of the dual CFT and find exact agreement with the Bekenstein-Hawking entropy of the Kerr-MOG black hole. We also show that the low-frequency scalar absorption cross section~(greybody factor) in the near-region Kerr-MOG geometry precisely matches the finite-temperature absorption cross section of the dual 2D CFT. In addition, the near-region scalar wave equation exhibits a hidden $(SL(2,\mathbb{R})_L \times SL(2,\mathbb{R})_R)$ conformal symmetry. These independent results provide strong evidence for the existence of a Kerr/CFT-type holographic duality for the Kerr-MOG black hole, establishing a consistent correspondence between the four-dimensional Kerr-MOG spacetime and a two-dimensional conformal field theory. Furthermore, the hidden conformal symmetry is realized in the form of $\rm {Vir_L} \otimes \rm{ Vir_R}$ diffeomorphisms which act non-trivially on the black hole horizon.

The quantum electrodynamics for massive fermions carrying electric and magnetic charges, the dyons, is proposed based on the 1960's seminal works by Cabibbo, Ferrari, and Salam, with the gauge group being $U(1)\times U(1)$, which is associated to a vector field (photon) and a pseudo-vector field (metaphoton), wherein the Dirac quantization is set aside. At the tree level the spectrum consistency of the model is analyzed, and all continuous and discrete symmetries are established. The quantum analysis is performed by using the Becchi-Rouet-Stora (BRS) algebraic renormalization method, which is independent on any regularization scheme. Moreover, thanks to the presence of massless gauge fields, the Lowenstein-Zimmermann (LZ) subtraction scheme is required within the framework of the Bogoliubov-Parasiuk-Hepp-Zimmermann-Lowenstein (BPHZL) renormalization procedure. Finally, it is verified that the proposed model, the dyon quantum electrodynamics (dQED), is free from any anomaly and is multiplicative renormalizable at all orders in perturbation theory, proving, therefore, its quantum consistency.

The identification of the $21\,μ\mathrm{m}$ feature in some protoplanetary nebulae remains a longstanding puzzle, whose interpretation requires characterization of the molecular gas environments of associated sources. Here, we present high-resolution interferometric observations from the Northern Extended Millimeter Array toward the $21\,μ\mathrm{m}$ protoplanetary nebula IRAS 06530-0213. Multiple molecular transitions of $\mathrm{HC_3N}$, $\mathrm{C_4H}$, and $\mathrm{SiC_2}$ are detected and spatially resolved. We analyze these spectral lines alongside previously reported CO and $^{13}\mathrm{CO}$ emission toward this source. Differing from the extended barrel-like molecular structure traced by CO and $^{13}\mathrm{CO}$, $\mathrm{HC_3N}$ and $\mathrm{C_4H}$ are predominantly concentrated in the inner low-latitude equatorial zones. Reproducing the observed morphology requires $\mathrm{HC_3N}$ to possess a more inwardly concentrated abundance distribution compared with CO and $^{13}\mathrm{CO}$, implying that the inner equatorial regions provide favorable conditions for carbon-chain chemistry.

In this study, we investigate the fermionic helical asymmetry during preheating by introducing a model in which the Dirac field $ψ$ couples to the scalar inflaton $φ$ directly through the pseudoscalar Yukawa mechanism described by the term $- g\fracφ{f} m_ψ\barψ\mathrm{i}γ^5 ψ$. Following inflation, as the inflaton oscillates around the minimum of its potential, the effective frequency of Dirac field changes non-adiabatically, resulting in particle production. These oscillations also indicate that the pseudo-mass $m_5 = g φm_ψ/f$ changes the sign, leading to the production of helical-asymmetric fermions. We employ the WKB method to analytically calculate the transition relations of the Bogoliubov coefficients, which is valid for an arbitrary number of productions and demonstrates a significant difference compared to the case without asymmetry. In the expanding universe, the presence of pseudo-mass $m_5$ alters the Gaussian distributions for each helical state, since the combined effects of Pauli blocking and parametric resonance produce coherent enhancement and coherent suppression in certain frequency ranges. This departure arises from the imaginary component of the first-order adiabatic complex phase, denoted as $Θ^{(r)}_{1}$. The real part of $Θ^{(r)}_{1}$ significantly enhances the number density of each helical state after eight oscillations of the inflaton since the coherent superposition. These conclusions have also been validated by the numerical results.

We show that the Levi-Civita connection for the Taub-NUT metric is singular on Misner strings and generates an Einstein tensor containing the squares of the delta function. This can be improved by introducing torsion, in which case the Einstein tensor may be interpreted as that of a cosmic string with negative variable tension. Komar flows in Misner strings are generated by torsion, which is therefore responsible for the asymptotic Komar charges. The Taub-NUT metric then appears as a soliton supported by two spin-fluid beams.

Detailed studies of the physical characteristics of young intermediate-mass Herbig Ae/Be (HAeBe) stars require extensive sets of homogeneous observational data collected over long periods. In this paper, we present the results of a multi-year study focusing on the faint Herbig Ae/Be star AS 442A. The goal of this study was to investigate the spectral and photometric variability of the star, utilizing long-term archival photometry alongside our own spectroscopic observations. The long-term photometric variability was statistically investigated using approximately 3,500 archival measurements spanning 1984 to 2025. Additionally, we examined the star's spectral variability using data obtained at the Shamakhy Astrophysical Observatory (ShAO) between 2020 and 2024. The three deepest brightness minima were detected in 1990, 2013, and 2023, with amplitudes of approximately ~2 mag in the U-band and up to ~1 mag in other bands. All three observed deep minima were accompanied by smaller brightness dips occurring both before and after the main event. The main light curve and color-magnitude diagrams show the "blueing" effect, which is characteristic of UXOR stars. A quasi-periodic occurrence of deep brightness minima with a period of P = 3759 +/- 35 days was detected for the first time. Our spectral observations were performed before the last deep light fading, which occurred in 2023. We show that the observed spectral variability, specifically the strengthening of emission lines and the reduction in depths and widths of absorption lines, is primarily related to the star's brightness variations. We have shown for the first time that the main reason for the UXOR-like brightness dip of the HAeBe star AS 442A can be explained by a periodic eclipse in a binary system. A close companion as a late-type secondary star with an orbit semimajor axis (a>7.5 au) likely drives the observed stellar variability.

We present long-slit spectroscopic observations of the outflow associated with an infrared source IRAS 01166+6635, conducted with the 6-m telescope of the Special Astrophysical Observatory using the SCORPIO-2 focal reducer. The structure of the flow as investigated in detail, its position-velocity diagrams are constructed. The electron densities of the several knots in the outflow were estimated, revealing a decrease in its density with increasing distance from the driving source.

We establish the weak gravitational lensing convergence trispectrum as an independent probe of cosmological parity violation in the late-time Large-Scale Structure (LSS). To map three-dimensional primordial symmetries into two-dimensional observables, we derive a generalized, compact projection formalism for the reduced angular trispectrum applicable to two classes of factorizable primordial curvature trispectra considered in this work. Applying this framework, we compute the parity-odd signal and forecast the expected Signal-to-Noise Ratio (SNR) using two phenomenological parity-violating trispectrum templates. These two templates encode the initial conditions for the late-time weak lensing observables. One template peaks at the squeezed limit, and the other template peaks at the collapsed limit. Our analysis evaluates idealized Dirac-delta source redshift distributions alongside actual tomographic profiles from the Dark Energy Survey Year 3 (DES Y3) and forecasted profiles for the Legacy Survey of Space and Time Year 10 (LSST Y10). We map the geometric sensitivity of these templates, providing physical intuition into how the resulting SNR is strongly modulated by the specific source galaxy redshift distributions and the underlying geometry of the configurations. Furthermore, we rigorously test the validity of the Limber approximation for higher-order angular statistics, demonstrating the necessity of exact line-of-sight numerical integration to capture the parity-violating signal accurately. By demonstrating the theoretical detectability of parity-breaking signatures through weak lensing, this work serves as a proof of principle, showing how upcoming weak lensing surveys can be leveraged to probe the fundamental symmetries of the early universe.