高能暂现源 · 每日文献综述

Black holes that merge repeatedly carry a record of that history in their mass distribution. We treat hierarchical merging as a coagulation problem, in which a single kernel encodes how the merger rate depends on the masses involved and on cosmic time, and we derive the late-time spectra that such populations approach. The framework yields closed scaling laws, an exactly solvable benchmark, and a classification of merger environments by a single exponent measuring how strongly mergers favor or suppress massive participants. Applying it to primordial black holes requires care in translating published merger rates into kernel form; done correctly, three of the four standard binary-formation channels map onto superlinear kernels and are therefore candidates for runaway growth, in which the heaviest objects would dominate and no steady mass-conserving spectrum exists; establishing physical gelation, however, requires the full population-dependent kernel and its finite coagulation history, neither of which we settle here. Only the early three-body channel maps into the nongelling regime and admits slow self-similar growth. Numerical solutions across thirteen suppressive, nongelling kernels show that the shape of the spectrum is not fixed by the scaling exponent alone, and that accounting for the energy radiated at each merger measurably changes the high-mass cutoff and drains the population's total black-hole mass.

We present the first results from the Compact Objects and the Physics of Accretion Survey (COPAS), a high-cadence photometric survey focused on the detection of accreting white dwarf binaries mainly through their outbursts using TESS. From an initial sample of 2,054 cataclysmic variable (CV) candidates observed during TESS Cycle 6 and 7, we identify 11 systems with periods below 83 minutes. This includes 7 AM CVns and 4 CVs. Our Gemini spectroscopic data confirm ZTF18aaxuusk and ASASSN-21eo as AM CVns, while Gaia21akb is confirmed as a CV. We provide the first period measurements for 6 out of the 11 systems. Complementing our TESS data with ground-based observations, we measured superoutburst recurrence times of approximately one year for the AM CVn systems ASASSN-21in and ZTF18aaxuusk, and 1.8-2.0 years for the short-period CVs ASASSN-18rd and ASASSN-15ev. Using TESS, we also estimate the mass-ratio for ASASSN-19ct (q = 0.05 +/- 0.02), which is consistent with a highly evolved low-mass donor star. Though the number of ultracompact systems detected among the total sample is low (0.54%), and likely the result of observational biases and intrinsic population rareness, the reclassification of 5 systems as AM CVns highlights the importance of continuous monitoring to identify more systems through their outbursts and short periods.

The pHz to sub-nHz GW regime remains largely unexplored but is crucial for mapping the early inspiral stage of SMBHBs and probing early-Universe physics. Astrometry and pulsar timing offer orthogonal and deeply complementary secular observables to investigate this frequency band. We aim to present the first joint data analysis combining real astrometric proper motions with binary pulsar timing, to search for and constrain continuous gravitational waves (CWs) sourced by SMBHBs in the ultra-low-frequency regime ($10^{-12} \le f_{GW} \le10^{-9} Hz$). We employ a Bayesian model selection and upper limit estimation framework to combine apparent proper motion displacements of $\sim 1.5 \times 10^6$ quasars from the Gaia CRF3 catalog with the line-of-sight orbital period derivatives ($\dot{P}_b$) of 11 high-precision binary pulsars. To prevent spurious detections, we heavily model instrumental and astrophysical systematics: we propagate the Galactic potential uncertainty for pulsars via Monte Carlo simulations and perform a Vector Spherical Harmonics (VSH) decomposition up to the octupole order (l=3) for quasars. We find no statistically significant evidence for a CWs signal in the joint analysis ($\ln B_{joint} = -0.42 \pm 0.03$). In the absence of detection, we set the tightest constraints to date on CW strain in the pHz band, yielding a 95% upper limit of $h_0\le6.4x10^{-11}$ at a reference frequency of $f_{ref} = 4 \times 10^{-10}$ Hz. The combined dataset achieves full sky coverage and improves single-dataset upper limits by 20%-30%. Combining orthogonal observables successfully breaks spatial degeneracies intrinsic to isolated searches. Furthermore, forecasts from inj.-rec. indicate that with the extended temporal baseline and reduced uncertainties of the upcoming Gaia DR4, this joint framework is poised to break the $h_0 < 10^{-11}$ upper limit barrier for sub-nHz CWs.

The core-collapse supernovae (CCSNe) 2022prr, 2023ucy, and 2024ljc exploded within the central regions of the nearby luminous infrared galaxy (LIRG) NGC6745. We present our follow-up data with the aim to characterise the spectrophotometric evolution of these CCSNe, determine their host-galaxy extinction, and to define their physical nature. The presented spectrophotometric data set covers the optical and near-infrared region for our three supernovae (SNe). The data are analysed and compared to other hydrogen-rich CCSNe, and a host-galaxy extinction value Av is derived based on broadband photometry for each of the targets. A spectral energy distribution (SED) for the host galaxy is constructed, and a combination of different galactic components are fitted to the SED to estimate the intrinsic CCSN rate and the age of the starburst of NGC6745. 2022prr is a SN2009ip-like event, whose light curve evolution consists of two consecutive luminous events A and B with peak magnitudes of Mr = -14.8 and -18.3 mag, respectively. The high degree of V and R-band polarisation (P=2.8%) near maximum light suggests interaction with highly aspherical circumstellar material. The spectral evolution of the SN is dominated by narrow Balmer emission lines, which have a complex evolution over time. 2022prr joins the growing sample of SN2009ip-like events that show early `flash ionisation' features of CIII, NIII, and HeII. 2023ucy is found to be a normal Type IIP SN. However, 2024ljc is a rapidly evolving Type IIb SN with a post-maximum r-band decline of roughly 3.2 mag by +41 d whereas normal IIb SNe decline typically by 1.5+/-0.3 mag during the same timescale. While the events exploded in a LIRG, the SNe are obscured by only moderate V-band host extinctions ranging from 0 to 1 mag. Based on the SED modelling we estimate an age of the host starburst to be 40Myr, and the intrinsic CCSN rate to be 0.4+/-0.1 SN/year.

In the Fermi-LAT gamma-ray light curve from January 1 to August 25, 2026, of the changing look blazar B2 1420+326, we report here the detection of transient quasi-periodic oscillations (QPOs) of period ranging around 10-13 d. The source entered the flare state around May 7, 2026, and lasted till around mid-August, 2026 during which it depicted strong QPO signatures. We utilized standard techniques, including weighted wavelet Z-transform analysis, generalized Lomb-Scargle periodogram, and phase dispersion minimization, to search for and confirm these findings. Prior to the flare, the source displayed a mild damped oscillatory feature of similar periodicity with a damping timescale of around 20 d. Based on the period timescale and nature of the QPOs detected, we discuss possible physical mechanisms for the observed salient features.

We present COBALT-BLUE, a fast public model for the optical light curve of a luminous star in a non-accreting binary with a compact object. The model includes gravitational self-lensing, Doppler beaming, ellipsoidal variations, eccentric orbital geometry, and wavelength-dependent limb darkening. In sufficiently edge-on systems, it predicts sharp periodic self-lensing flares together with phase-locked orbital modulation outside the flare. We improve upon earlier models by including non-linear limb darkening laws based on stellar atmosphere simulations to calculate the self-lensing flare profile. This enables light curves to be self-consistently calculated in multiple wavebands from one set of physical parameters, thus offering the prospect of constraining binary parameters such as compact object mass from photometry alone if multiple self-lensing flares are observed. We also include the option to utilise simpler limb darkening prescriptions to save computational expense. As a proof of principle, we fit our model to ZTF data of 14 candidate self-lensing sources. The model describes the flare morphology well for most candidates, but we find that the best fitting parameters are not physically plausible. We conclude that the observed flares are most likely stellar flares and not self-lensing events. In future, we plan to use the model to systematically search optical survey data for signatures of binary motion.

When simulating dynamically unstable neutron stars, truncation errors can introduce perturbations that drive the stellar configuration either toward gravitational collapse into a black hole or toward migration to a dynamically stable, lower-density configuration. This mechanism has become a standard benchmark for validating general-relativistic hydrodynamics codes in the case of spherically symmetric neutron-star models. In this work, we extend the analysis to the more general case of uniformly rotating neutron stars evolved in three spatial dimensions. We investigate these transitions using two equations of state: a cold polytrope and a hybrid prescription, which allow us to distinguish the barotropic response from the effects of shock-generated thermal pressure. We find that the migrated remnant remains close to uniform rotation after the transition, and we trace its quasi-radial pulsations through complementary diagnostics involving the central density, the rotation profile, and the axisymmetric gravitational-wave channel. We investigate the properties of these transitions and propose a standardized test for validating numerical-relativity codes by requiring the migration behavior to be consistent with the dynamics reported here.

The Auger Radio Infill SKALA Extension (ARISE) was installed at the Pierre Auger Observatory in 2025 to detect the radio emission in the band of $50-350\,$MHz of near-vertical cosmic-ray air showers of energies around and above $100\,$PeV. The array comprises 18 SKALA~v2 antennas deployed around one of the surface-detector stations of the $433\,$m array (SD-433), which provides the trigger for ARISE. We present first measurements with ARISE and show the detection of radio pulses associated with extensive air showers. Radio signals are found in coincidence with SD-433 events, and a comparison of the arrival directions reconstructed from the radio and surface detector signals confirms the measurement of air showers with ARISE. These observations provide a first assessment of the detector setup and demonstrate the potential of ARISE for radio detection of near-vertical air showers.

Purpose: Very-high-energy gamma-ray astronomy is an important window to study the extreme astrophysical processes in the universe, and how to effectively distinguish between gamma photons and background signals (mainly protons) is a key technical challenge to realize very-high-energy gamma-ray detection. Spaceborne calorimeters record secondary particle spatial distributions, achieving a background rejection power of 10000-100000 near 1 TeV. Ground-based imaging Cherenkov telescopes measure Cherenkov photon angular distributions, yet they only reach a rejection factor of about 10 in this energy range, leaving substantial room for optimization. Methods: We use CORSIKA and sim_telarray to simulate H.E.S.S. detector responses. Photon emission positions are reconstructed from Cherenkov shower images. Inspired by analysis techniques for space-borne calorimeter, we propose new observables derived from the transverse distribution of Cherenkov photon emission positions to separate gamma-ray signals from proton backgrounds. We employ a likelihood-ratio method to combine single-telescope variables across multiple telescopes and compare its performance with conventional Hillas-based analysis. Results: The results show that observables built from the transverse distribution of Cherenkov photon emission positions are less sensitive to Cherenkov image size and outperform the Hillas width parameter for single-telescope gamma-proton discrimination. Furthermore, the likelihood ratio combining width yields substantially better performance than the conventional mean reduced scaled width: the improvement reaches roughly one order of magnitude near 1 TeV, and this enhancement remains above 50% for energies above 10 TeV.

Gravitational waves couple in a nonlinear fashion in the vicinity of a black hole. Black hole perturbation theory can be readily applied to compute the magnitude of this coupling, its dependence on the parity content, frequencies, and angular structure of the incoming gravitational waves. In this work we carry out this calculation, showing how the nonlinear coupling of gravitational waves generically peaks when the driven frequency matches the oscillation frequency of the fundamental quasinormal mode of the black hole. We also demonstrate how this excitation is largest at the maximal harmonics allowed, and that it only depends mildly on the parity content of the incoming modes. At low frequencies, the quadratic response computed here encodes the nonlinear, dynamical tidal deformability of the black hole spacetime itself. We demonstrate numerically that the quadratic black hole coupling coefficient scales quadratically with the driving frequency, and recover this scaling from the 5-point Compton graviton scattering amplitude.

We report on the observation of the Compton-thin Seyfert galaxy NGC~5506 performed with the Imaging X-ray Polarimetry Explorer (IXPE). The observation, with a net observing time of 975~ks, was partly simultaneous with \textit{NuSTAR} (52~ks) and \textit{XMM-Newton} (37~ks). Using a simple baseline model with IXPE data only, we find an upper limit on the 2--8~keV polarization fraction at the $99\%$ confidence level: $Π<3.1\%$. We then performed a spectropolarimetric analysis combining data from the three X-ray observatories. While pure spectral modeling confirms the presence of both relativistic and cold distant reflection, in addition to the primary continuum power law, their contributions lead to somewhat different constraints on the coronal $Π$, depending on the specific assumptions. We also performed Monte Carlo simulations with the radiative transfer code \texttt{MONK}, exploring various coronal geometries. Comparing these results with the IXPE data, and assuming a radially extended corona, as suggested by previous observations of similar sources, the corresponding polarization upper limits require inclination angles below 40°.

The hotspots of powerful radio galaxies are the sites of high-energy particle acceleration, but radio observations give us limited information on the electron energy distributions that they generate, which affects our overall understanding of their physics and energetics. Optical synchrotron counterparts to radio galaxy hotspots, which probe high electron energies, have been known for many years, but have only been studied in a small number of objects selected as being very bright in the radio. By combining Low-Frequency Array (LOFAR) observations with the Euclid Q1 data release in the Euclid Deep Field North, we identify 77 powerful radio galaxies with hotspots and show that a small but significant fraction of them, 7--15\%, may have detected infrared and optical counterparts to their hotspots. The hotspot spectral energy distributions in our clearest cases are consistent with particle acceleration up to (but not beyond) 1\,TeV in energy on the assumption of field strengths close to equipartition, whereas non-detected hotspots either do not reach such high electron energies or would have to have very different electron energy spectra or significantly sub-equipartition magnetic field strengths. Two new candidate optical hotspots are clearly detected matching high-resolution LOFAR data; one is remarkable as both the highest-redshift optical hotspot known to date ($z \approx 1.6$) and also the first optical detection of the hotspot of the inner lobe of a restarting source. We discuss approaches to performing a large-scale study of hotspots with the full wide-area Euclid surveys, particularly when combined with the international baselines of LOFAR, enabling for the first time a statistical analysis of high-energy particle acceleration in hotspots.

Little red dots (LRDs) may be powered by supermassive black holes (SMBHs) accreting above the Eddington limit. Spectroscopy of LRDs often shows absorption troughs blueshifted by $\sim100-300\,{\rm km\,s^{-1}}$, implying a slow wind. This is puzzling: super-Eddington disks drive much faster winds, $\gtrsim10^3-10^4\,{\rm km\,s^{-1}}$. We argue that LRDs are super-Eddington SMBHs viewed off-axis and engulfed in a slow wind that covers most sight-lines; the fast wind escapes near the poles. Trapped light puffs the inner disk into a quasi-spherical envelope that launches the slow wind. The wind may be ``photon-tired'', meaning the light only barely unbinds it. Such marginally unbound winds lead to fountain flows, where some gas escapes and the rest falls back. We model the envelope with idealized, spherically symmetric ``marginally unbound'' ($v\sim v_{\rm esc}$) and ``photon-tired'' winds. We feed these profiles into the radiative transfer code Sirocco to study how the wind reprocesses the light from an accreting $10^6\,M_\odot$ SMBH. We describe most of the wind as a ``Balmer cocoon'' -- a Compton-thick region in which depletion of Balmer continuum photons ($hν>3.4\,{\rm eV}$) rather than Lyman continuum photons ($hν> 13.6\,{\rm eV}$) keeps the gas ionized. The spectra span the range of LRD-like sources: ``little blue dots'' at lower outflow rates ($\sim2.5\,M_\odot\,{\rm yr}^{-1}$); V-shaped LRDs with a Balmer break ($\sim5-10\,M_\odot\,{\rm yr}^{-1}$); and red LRDs with full breaks ($\sim15\,M_\odot\,{\rm yr}^{-1}$). Our Balmer line profiles show P~Cygni features atop broad, exponential wings, as is observed. The break is possible at lower wind densities than in LTE models because Lyman~$α$ trapping sustains our $n=2$ hydrogen population and electron scattering enhances the optical depth. Our arguments are also applicable to winds from supermassive stars or quasi-stars.

Wide binaries containing white dwarfs (WDs) provide a pathway to exploring post-main-sequence (MS) natal kicks associated with asymmetric mass loss. In this work, we develop a binary population synthesis model that involves episodic mass loss and velocity kicks during the thermally-pulsing asymptotic-giant-branch (TP-AGB) phase of stellar evolution, when mass loss is expected to be most significant. We compare our synthesized populations against the Gaia DR2 and DR3 data for wide WD-MS and WD-WD binaries, varying the number, strength, and directionality of TP-AGB kicks. We find that the observed separation distribution can constrain the kick strength, but it alone is insufficient to also constrain the kick number and dimensionality. We therefore additionally constrain our models using the observed eccentricity distributions. Models where mass loss induces a random walk in the star's velocity are most consistent with observed eccentricity constraints for WD-MS binaries. No models are found to agree with the WD-WD eccentricity constraint. Our results suggest that at least 10 randomly directed kicks take place during the TP-AGB phase, leading to a cumulative root-mean-square kick velocity of approximately 0.7 km/s. These findings constrain the nature of WD natal kicks, connecting the orbital distributions of evolved wide binaries to asymmetric mass loss during the final stages of stellar evolution.

Gamma-ray observations of Milky Way dwarf galaxies provide some of the strongest constraints on dark matter annihilation and are approaching the sensitivity required to test dark matter interpretations of the Galactic Center Gamma-Ray Excess. The results, however, depend critically on the inferred dark matter distributions in these systems, conventionally described by their $J$-factors and spatial profiles. We review several sources of systematic uncertainty in dwarf galaxy $J$-factor determinations, including stellar membership, unresolved binaries, departures from equilibrium and spherical symmetry, and assumptions regarding the stellar and dark matter density profiles. Most $J$-factor determinations reported in the literature neglect several of these uncertainties, and the resulting measurements are often more dispersed than their quoted uncertainties would suggest. This indicates uncertainties of order $Δ\log_{10}J\sim0.5$ or larger may be warranted for many of these systems. Using an ensemble of simulated Fermi-LAT observations of a stacked sample of 27 dwarf galaxies, we quantify how these unmodeled uncertainties affect the resulting constraints on the dark matter annihilation cross section. We find that adding an uncertainty of $Δ\log_{10}J\sim 0.5$ or 1.0 in quadrature weakens the median upper limits of a stacked analysis by factors of 1.4 or 3.2, respectively. Furthermore, underestimating these uncertainties can cause such analyses to exclude the true annihilation cross section more frequently than the nominal confidence level would imply. Such undercoverage is especially pronounced in stacked analyses and persists even when the adopted and true $J$-factor uncertainties agree. Mismodeling spatially extended halos as point sources, as is sometimes done, further strengthens the resulting limits and increases the probability that true signals will be incorrectly excluded.

Baryonic feedback processes redistribute gas within and beyond dark matter halos, however, the resulting gas distribution remains highly uncertain, limiting predictions of the matter distribution for precision cosmology. We introduce a physically motivated approach to modelling the gas distribution that decomposes it into an approximately hydrostatic inner component and a diffuse outer component. This approach takes advantage of the growing observational landscape: X-ray measurements primarily probe the dense inner halo, while the kinetic Sunyaev-Zel'dovich (kSZ) effect is sensitive to diffuse ionized gas extending to larger radii. We implement this two-component profile within the baryonification framework, though we note that it is applicable to any model of the large-scale gas distribution. We jointly fit X-ray gas-fraction measurements from the HSC-XXL and eROSITA samples with stacked kSZ effect measurements of BOSS CMASS galaxies from the Atacama Cosmology Telescope, demonstrating that the proposed profile retains sufficient flexibility. This proof-of-concept shows that a decomposition between hydrostatic and diffuse gas provides a simple, physically interpretable framework for connecting complementary observations of the gas distribution, and a foundation for future models of baryonic feedback.

The presence of a dark energy (DE) core, made of a Chaplygin dark fluid, is capable of influencing the diverse observable properties of neutron stars (NSs). However, there is also the possibility that NSs could contain a mixture of ordinary nuclear matter and DE. In this perspective, we propose an equation of state (EoS) that includes both normal matter and DE, where a free parameter $f$ quantifies the ratio of DE density with respect to the total energy density. As expected, in the limit $f \rightarrow 0$ we recover the already known results corresponding to pure nuclear matter. Remarkably, increasing this fraction $f$ leads to a softer EoS and thus strongly favors the fulfillment of the causality condition. As a consequence of our mass--radius results, the central compact object in HESS J1731-347 can be satisfactorily described as a DE admixed NS. For sufficiently high stellar masses, our calculations further indicate that both the gravitational redshift and the fundamental nonradial oscillation frequency increase significantly with an increasing DE fraction, whereas the opposite trend is observed for the total gravitational mass and tidal deformability. As is typical for compact stars composed purely of ordinary matter, we find that in our DE admixed stellar models the central density corresponding to the maximum-mass configuration coincides with the point at which the squared radial vibration frequency vanishes. Moreover, higher DE concentrations lead to enhanced stability of these configurations.

Integrating out heavy particles is generally viewed as an irreversible procedure that erases some physical information above the cutoff scale of the resulting effective theory. However, this does not preclude the possibility of recovering the heavy propagating degrees from the low-energy effective theory with appropriate boundary data supplied. A classic example is the recovery of Schwinger pair production from the resummed Euler-Heisenberg effective action. In this work, we perform a similar exercise in a cosmological setting. We show that it is possible to reconstruct the inflationary correlators with massive exchanges, for a discrete heavy spectrum and arbitrary tree topologies, from the low-energy effective theory together with unitarity and Bunch-Davies boundary conditions. The divergent EFT series is resummed in three ways: the boundary differential operators, spectral representation, and Borel resummation, and the exponentially suppressed cosmological collider signals are recovered via analytic continuation. Our construction provides a resurgent relation between the local EFT background and the nonanalytic heavy-particle production, and may also be viewed as an inverse problem for the dispersive bootstrap.

We study a degenerate, zero temperature, fermion gas with rest mass $m$, that only interacts with itself, gravitationally. We describe a self-consistent novel approach to the formation of a degenerate, quantum mechanical, star. In this approach, the fermions occupy the energy levels that are determined by the self consistent gravitational interactions, according to the Pauli exclusion principle. Then in this novel approach, the size of the highest occupied level determines the radius of the star. In the Newtonian gravitational limit, the fermions feel a potential corresponding to a simple harmonic well that smoothly attaches in the exterior to the usual $1/r$ Newtonian gravitational potential. We find analytically, solutions for stars with any radius and mass, parametrized by $m$ and $N_s$, the total number of fermions. In the Newtonian limit, we easily find that we can construct a star that is more compact than the Buchdahl bound and indeed can even be smaller than the Schwarzschild radius. Clearly, such cases are outside of the purview of the Newtonian limit. Therefore we expand our analysis to fermions in the general relativistic context, interacting gravitationally with a metric. We consider the metric corresponding to the interior Schwarzschild solution smoothly connecting to the usual exterior Schwarzschild metric. Treating matter semi-classically, we recover the Buchdahl bound in a completely independent analysis. We briefly discuss classical stability of the Newtonian solution, and its relation to Newtonian polytropic fluids.

Radiation pressure and radiative cooling often play an important role in deciding the structure and dynamics of astrophysical objects. In this paper, we present a radiative MHD simulation of a circumbinary disk (CBD) around an equal-mass SMBBH. It employs an approximate thermodynamic model based on local thermodynamic equilibrium and diffusion cooling which captures how the internal energy evolves in an optically thick region. The disk reaches a quasi-steady state within $r=5a$ whose mass distribution differs substantially from the one obtained from simulations without physical thermodynamics: the local maximum in the azimuthally-averaged surface density and the lump are completely erased; the time-averaged inner edge becomes more eccentric; and the vertical density distribution depends strongly on the radius. These changes are attributable to the enhancement of the magnetic fields caused by the cooling-driven vertical compression of the disk. Our result emphasizes that the basic properties of the inner CBD are sensitive to both radiation and magnetic physics.

The start of the Legacy Survey of Space and Time marks a new era for strong lensing science, where the number of strong lenses identified is expected to increase to $\mathcal{O}(10^5)$. In this paper we use a neural network to determine the precision with which lens parameters can be determined, using realistic simulated LSST lensed systems. We find that the Einstein radius can be measured with a mean precision of $3.7\%$ with calibrated uncertainties accurately reflecting the corresponding measurement error. Based on the performance of current strong lens classifiers, the $\sim 100,000$ detectable strong lenses are expected to be accompanied by a similar or larger number of false positives (non-lenses). In readiness for this we introduce a formalism, termed `COSMIC-BEAMS', to infer cosmological parameters while accounting for contamination by false positives. As a proof-of-concept, using simulated LSST measurements of the Einstein radii of a realistic and impure sample of photometric lens systems, i.e. those without spectroscopic confirmation, we find that the cosmological parameters $Ω_m$, $Ω_Λ$, and $w$ can be measured to a precision of $0.1$, $0.03$ and $0.15$ respectively for a $w$CDM cosmology. We demonstrate that unbiased cosmological parameters can be inferred even in strong lens samples contaminated by $50\%$ false positives, and that the photometric dataset of $100\,000$ strong lenses will provide equivalent $w$-precision to $2500-3500$ spectroscopic systems.

We present high-resolution cosmological hydrodynamic simulations of the Warm-Hot Intergalactic Medium (WHIM) using the GPU-optimized grid-based hydrodynamic code Kratos. Employing a uniform 4096^3 grid in a (100 h^-1 Mpc)^3 comoving volume, we achieve a spatial resolution of ~24.5 h^-1 kpc, sufficient to resolve the Jeans scale of gas at T ~ 10^4 K and n_H ~ 10^-3 to 10^-2 cm^-3. This calculation ranks among the largest grid-based cosmological hydrodynamic simulations performed to date. We find that ~23.4% of cosmic baryons reside in the WHIM phase (T = 10^5 - 10^7 K) at z = 0, significantly below the 40-50% found in earlier, lower-resolution simulations. Through a suite of lower-resolution simulations, we demonstrate that spatial resolution plays a pivotal role in determining the WHIM fraction: resolving gas near its Jeans scale allows it to reach higher densities, where enhanced radiative cooling transfers a substantial fraction of baryons out of the WHIM temperature range. The remaining WHIM resides predominantly in filaments and accretion-shock structures in the vicinity of halos, where hierarchical structure formation and ongoing hydrodynamic accretion provide continued shock heating. Synthetic observations of Lyman-alpha, O VI, O VII, and O VIII emission reveal distinct morphological and kinematic signatures, with O VI tracing filament-halo interfaces and the X-ray lines probing hotter gas associated with massive halos. These predictions underscore the importance of current and future missions such as XRISM, ATHENA, and HUBS for mapping WHIM thermodynamics and kinematics.

While background expansion data alone cannot discriminate among cosmological models, the growth of large-scale structures directly probes the underlying theory of gravity, offering a path to distinguish General Relativity from its modifications. In this work, we constrain three representative $F(R)$ modified gravity models (Starobinsky, Hu-Sawicki, and $R^2$-corrected Appleby-Battye) using measurements of the growth rate $f(z)$ and the matter fluctuation amplitude $σ_8(z)$. Our analyses combine MCMC parameter estimation, Gaussian Process reconstructions, and goodness-of-fit statistics including Akaike information criterion (AIC) and Bayesian information criterion (BIC). All investigated models provide statistically comparable fits to the current growth data, with information criteria differences too small to establish a preference for any particular scenario. To overcome this degeneracy, we reconstruct the effective gravitational coupling $μ(z)$ from the MCMC posterior samples, providing a physically motivated diagnostic that complements standard goodness-of-fit criteria. The Starobinsky and Hu-Sawicki models predict moderate departures from General Relativity, remaining compatible with constraints on both $μ(z)$ and $S_8$. In contrast, the $R^2$-AB model predicts $μ_0 \sim 3.5$ and $S_8 = 0.638$, a $3.2σ$ tension with Planck 2018, rendering it physically disfavored despite its competitive statistical performance.

JWST has revealed rapid nitrogen enrichment in high redshift galaxies, renewing the need for stellar yields that follow metal free stars beyond the main sequence and across their final fates. We present Geneva stellar evolution models of rapidly rotating Pop~III stars with $5 \leq M_{\rm ini}/M_\odot \leq 200$ and $\upsilon_{\rm ini}/\upsilon_{\rm crit}=0.7$, evolved to the end of core O-burning. We calculate gross adopted ejecta masses using fate dependent remnant prescriptions spanning core collapse, pulsational pair instability, and complete pair instability. Our quantitative results focus on hydrostatically produced CNO material, while heavier species are treated as final-model reservoirs. Rotation produces primary CNO material by mixing newly synthesized C and O into H-burning layers, where CNO cycling generates nitrogen. The resulting abundance signature depends strongly on which stellar layers escape. Models leaving compact remnants can reach $\log({\rm N/O})=-0.49$ while remaining poor in Si/S/Ar/Ca-rich material. PISN models eject the largest nitrogen masses, $M_{\rm N}=1.8$--$2.5,M_\odot$, but also release $57$--$65,M_\odot$ of oxygen, lowering $\log({\rm N/O})$ to $-1.44$ to $-1.29$. Thus, high nitrogen yields do not imply high N/O ratios. This trend persists after IMF weighting, as increasingly top-heavy populations add oxygen and deep alpha material faster than they build a nitrogen dominated mixture. Our grid provides a new CNO-focused prompt-enrichment dataset for interpreting nitrogen-rich systems including GN-z11, CEERS-1019, and GS~3073.

Halo models provide the standard framework for interpreting cosmic infrared background (CIB) anisotropies and inferring the connection between dusty star-forming galaxies and their host dark matter halos. Recent studies have shown that inaccuracies in the modelling of halo clustering may bias the inferred parameters governing star formation in dark matter halos. In this work, we investigate whether a more detailed description of halo clustering can alleviate these shortcomings. We incorporate a scale-dependent, non-linear correction to the halo bias within a halo-model framework based on a simple SFR-halo mass parametrisation. We consider both a full mass-dependent implementation and a computationally efficient approximation. We also investigate the impact of updated (sub)halo mass functions. We validate the revised framework using mock observations derived from a dedicated simplified version of the SIDES-Uchuu simulation, combining the SIDES empirical galaxy model with the Uchuu N-body simulation, specifically designed to match the SFR prescriptions adopted in our halo-model. The corrections modify the predicted CIB clustering by up to 30% on intermediate scales, while the effective implementation reproduces the full treatment at the sub-percent level. The updated model removes the scale-dependent discrepancies previously identified and accurately reproduces the measured power spectra over the full multipole range. In MCMC analyses, the input SFR parameters are recovered with substantially reduced biases, with all input parameters recovered within their $1σ$ confidence intervals. Our results demonstrate that accurately modelling non-linear halo clustering is essential not only to reproduce CIB anisotropies, but also to reliably recover the underlying galaxy-halo connection. The framework presented here provides a validated foundation for future analyses of observational data.

Head-tail radio sources are jetted active galactic nuclei (AGN) moving through the dense intracluster medium of galaxy clusters. They are extremely rare in the gamma-ray sky, likely because they are usually observed at large viewing angles. Therefore, every new gamma-ray detection of head-tail radio galaxies allows us to probe the origin of the high-energy emission in this unique class of AGN. Here we report, for the first time, the association of ESO~0137-G007 (z=0.016), a head-tail radio galaxy located at the outskirts of the merging cluster Abell 3627, with the gamma-ray source FL16Y~J1615.5$-$6034. The motion of the galaxy through the dense cluster environment and subsequent ram pressure and/or intracluster medium turbulence have led to the formation of a $>$500 kpc-long jet exhibiting a twisted, wiggly radio morphology. Its optical spectrum, obtained with the 4.1 m SOAR telescope, is devoid of emission lines, indicating that the underlying accretion activity is radiatively inefficient. From the measured line-of-sight stellar velocity dispersion, we estimate the mass of the central supermassive black hole to be $(3.36\pm1.32)\times10^9$ \Msun. We briefly discuss several radiative models to explain the observed broadband spectral energy distribution of ESO~0137$-$G007. We conclude that deeper multi-wavelength observations of this unique gamma-ray emitting head-tail radio galaxy will enable us to better understand the interaction of the jet with the hot cluster environment, thus setting the stage for the research of this class of AGN with the upcoming Square Kilometer Array.

Thermodynamic topology provides a topological classification of black hole states and their branch structures in thermodynamic parameter space. We investigate the thermodynamic topology of the charged nonextremal magnetic Gibbons--Maeda family in four-dimensional asymptotically flat Einstein--Maxwell--dilaton gravity, with particular emphasis on its string-theory member at the dilaton coupling $a=1$, the Gibbons--Maeda--Garfinkle--Horowitz--Strominger (GMGHS) black hole. An analytic classification over the complete domain of regular outer horizons shows that the dilaton coupling separates the family into three limiting structures of the inverse Hawking temperature. At $a=1$, the GMGHS defect curve approaches a nonzero lower inverse temperature endpoint and contains a single unstable branch. In particular, the magnetic GMGHS black hole provides an explicit realization of the previously proposed $\overline W^{1-}$ thermodynamic topological subclass within an asymptotically flat Einstein--Maxwell--dilaton solution. This result demonstrates that the global topological number $W$ alone does not completely characterize black hole thermodynamic topology. The asymptotic behavior of the inverse Hawking temperature near the boundaries of the physical horizon domain provides an additional criterion for distinguishing thermodynamic topological subclasses with the same $W$.

The Treasury of Extremely Metal-Poor O Stars (TEMPOS) is a Hubble Space Telescope survey of hot and massive O-type stars in nearby, low-metallicity galaxies ($\lesssim$20% of the solar metallicity, $Z_\odot$). Understanding massive-star physics in this regime is essential to interpret observations of metal-poor galaxies, including both low-mass dwarf galaxies and chemically unevolved galaxies in the early Universe. Yet, few far-ultraviolet (FUV) spectra of O stars of sufficient quality to characterize their fundamental properties and stellar winds exist below 20% $Z_\odot$, and heterogeneous observation design and incomplete coverage of parameter space pose significant barriers to progress. To remedy this, TEMPOS obtained new Cosmic Origins Spectrograph (COS) FUV spectra of 12 very metal-poor O stars, building upon archival data to assemble a spectroscopic atlas of 29 homogeneously observed stars that efficiently samples a wide range of spectral types and luminosity classes. Here, we describe the motivation, sample selection, and observation design for TEMPOS and present the first data release of reduced and coadded COS spectra. We then present initial results on the empirical properties of FUV O-star spectra below 20% $Z_\odot$, including radial velocities, equivalent widths of photospheric lines, and terminal wind velocities ($v_\infty$). We show that $v_\infty$ correlates with host galaxy metallicity across $\sim$5-50% $Z_\odot$ and find tentative evidence of a steeper decline in wind strength below $\sim$10% $Z_\odot$. The combined dataset of FUV spectra and planned releases of photometry and optical spectra from the TEMPOS Treasury program will advance our understanding of both stellar astrophysics and the interstellar medium in the extremely metal-poor regime.

Phosphorus (P) is an odd-$Z$ element produced primarily in massive stars and is also important for planetary chemistry as an element essential to life. However, its evolution over cosmic time remains poorly constrained because precise and homogeneous stellar P measurements are scarce. We determine the relationship between [P/Fe] and [Fe/H] over a range of metallicities across the Galactic disk and assess its variation between different stellar populations using the largest uniformly analyzed sample to date, comprising $\sim$750 FGK stars with high-resolution near-infrared spectra. Stellar parameters are determined through a spectro-photometric approach and P abundances are derived by fitting synthetic spectra to the P~I 10529.52~Å absorption feature. We confirm that [P/Fe] increases toward lower metallicities down to [Fe/H] $\sim$ -1.0 dex, where it appears to peak, broadly resembling the rise seen in $α$-element abundance ratios over the same metallicity range and supporting a dominant contribution from massive stars on short core-collapse supernova timescales. When separating the sample into Galactic disk populations, thick-disk stars are systematically enhanced in [P/Fe] relative to the thin disk by $\sim$0.08 dex at fixed metallicity. We also measure a radial [P/Fe] gradient of $-0.124 \pm 0.006$ dex kpc$^{-1}$ and a vertical gradient of $+0.052 \pm 0.007$ dex kpc$^{-1}$. Although current chemical evolution models struggle to reproduce the observed trends, this survey increases the number of homogeneously measured stellar P abundances by approximately a factor of three, providing a new benchmark for Galactic chemical evolution models and the phosphorus inventory available to planetary systems.

The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) instrument onboard the balloon-borne Sunrise III observatory provided new high-resolution observations of the solar chromosphere in the Ca II 854.2 nm line. The Stokes-V signal in magnetic network regions was found to show fine-structured details, which suggests the magnetic field above the network elements does not simply expand as a unipolar feature but displays opposite-polarity-intrusions (OPIs). These features appear as elongated structures in Stokes-V observations. In this work, we demonstrate that such features appear ubiquitously in a numerical simulation of the solar chromosphere. We use a simulation that is computed with the recently developed chromospheric extension of MURaM (MURaM-ChE) and resembles an enhanced network region. We find that OPIs appear ubiquitously in the vertical component of the magnetic field at around 1 Mm above the surface and are visible in the synthetic Stokes-V signal of the Ca II 854.2 nm line. The structures have lengths of 2 Mm to 7 Mm and widths of approximately 1 Mm. The magnetic field configurations associated with the OPI features appear to belong to twisted flux ropes (TFRs) and are visible for most of the time in the presented 21 min time series. Our results show that the magnetic structure of the chromosphere is more complex than previously thought, with even seemingly simple flux tubes showing embedded twisted fields pointing in the opposite direction. This may help in explaining new high-resolution observations from the Sunrise III mission.

AutoTherm is a modular code automating the determination of thermal production and interaction rates for cosmology from Thermal Field Theory. This first release computes fully automatically the leading-order contribution from ultrarelativistic $2\leftrightarrow 2$ processes to the production rate of an off-equilibrium $\vartheta$ particle coupled to a thermal bath. It takes as input a FeynRules model file describing the Lagrangian of the bath-$\vartheta$ system. The AutoTherm program consists of a Wolfram package, which utilises FeynArts/FormCalc, together with a few Python modules for symbolic and numerical routines. Their combined usage leads from the model file to the rate, but each component can also be used in a standalone manner. The main strength of this release is the automated, model-independent handling of Hard Thermal Loop resummation, which is necessary whenever a $2\leftrightarrow 2$ process is mediated by a $t$-channel massless mediator. Developments in Thermal Field Theory reduce the apparently large model dependence to the determination of the thermal mass of the mediator, which we automate successfully. They further allow us to provide three leading-order-equivalent implementations of HTL resummation. Their spread provides a first estimate of the theory uncertainty from higher-order thermal corrections. We showcase the strength of our AutoTherm framework by successfully reproducing or correcting a host of results in the literature, such as the thermal production rate of ultrarelativistic right-handed neutrinos, of gravitons and gravitinos, of axions and of dark photons.

If ultrarelativistic supersymmetric particles are thermally produced in the early universe they would influence big-bang nucleosynthesis, dark matter and reheating constraints. While the basic framework for thermal gravitino and axino production is well established, the calculation is not completely settled. In this work, we revisit the problem using AutoTherm, a new tool which automates the computation of thermal rates from first-principles Thermal Field Theory, with control over the inherent theory uncertainty in Hard Thermal Loop resummation schemes. We demonstrate that the strict leading-order (LO) scheme, while unambiguous for hard momenta, can yield unphysical negative rates when extrapolated to soft momenta. To address this, we introduce a tuned scheme that ensures positivity and agreement with strict LO at high momenta, while avoiding gauge-dependent pathologies. We compare our results with existing parametrizations in the literature, identifying discrepancies and providing new, reliable fits for the gauge and Yukawa contributions to the gravitino and axino production rates. The choice of resummation scheme gives a theory uncertainty by a factor of $\sim 1.5$...$3$ depending on the temperature, which has been underappreciated until now. This residual spread should be taken into account in precision cosmological analyses of gravitino/axino abundancies.

We present a complete and homogeneous analysis of the Ly$α$ emission properties of the cosmic web at $3 \lesssim z \lesssim 5$ as a function of the overdensity of Ly$α$ emitters (LAEs) in the MUSE Ultra Deep Field (MUDF) and the MUSE Extremely Deep Field (MXDF). We identify 41 overdensities, probing environments that are $δ\approx 2 - 10$ times denser than the field. We search for extended emission down to surface brightness (SB) levels of $3 - 5 \times 10^{-20}\ \mathrm{erg\ s^{-1}\ cm^{-2}\ arcsec^{-2}}$, revealing filamentary structures beyond the scale of the circumgalactic medium, confirming that LAEs act as signposts of the cosmic web. A trend with overdensity emerges: non-detections are mainly at $δ< 2$, a $\approx 1$ dex scatter in SB appears for $2 \lesssim δ\lesssim 3.5$, and detections reach a maximum intrinsic SB of $\approx 2 \times 10^{-19}\ \mathrm{erg\ s^{-1}\ cm^{-2}\ arcsec^{-2}}$ for $δ\gtrsim 3.5$. Emitting regions occupy a fraction of projected area $f_s \approx 0.20 - 0.25$ inside filaments, yielding a cosmological incidence for Ly$α$ emission in the cosmic web $\ell(\mathrm{Ly}α)$ of $\approx 1.22$, which is similar to the one of partially-neutral Lyman limit systems. This analysis indicates that the emitting gas is partially ionized at moderate densities ($n_{\mathrm{H}} \approx 10^{-3} - 10^{-1}\ \mathrm{cm}^{-3}$), likely tracing the denser spines of intergalactic filaments and embedded substructures. Finally, we forecast how oriented stacking in larger samples of overdensities from shallower observations could yield an expanded view of the cosmic web before the next-generation wide-field spectroscopic instruments become operational.

White dwarfs are the most common end state of stellar evolution, including that of our own Sun, making their formation critical to completing a more comprehensive understanding of stellar evolution and even determining the eventual fate of the solar system. Wide binaries containing white dwarfs offer a powerful probe: their components evolve largely independently, yet stellar mass loss and velocity impulses (natal kicks) on the white dwarf progenitor leave measurable imprints on orbital properties. Previous population studies typically assume that each white dwarf receives only a single natal kick as it forms. While convenient, this simplification conflicts with simulations finding the formation process to be episodic. Therefore, a more realistic picture is that white-dwarf progenitors experience multiple stochastic kicks over their evolution. Here, we present a Fokker-Planck model for the evolution of binary orbital parameter distributions subject to many, randomly-oriented mass-loss-driven kicks. This model recovers key features of white-dwarf binary observations, including a -2 power law tail in the probability distribution of separations, and the thermalization of binary eccentricities beyond separations of 1000 au. We additionally investigate how white-dwarf kicks impact a myriad of other processes, such as binary dissolution, planetary system evolution, and even the production of interstellar objects.

We use a point-particle effective field theory to study the superradiant instability rates of an ultralight massive vector around a slowly rotating black hole. Earlier effective-theory treatments reported an apparent $O(1)$ discrepancy with the rates obtained by solving the Proca equation on a fixed black-hole background, e.g. for the mode with $j=1$ and $\ell=2$. We show that there is in fact no discrepancy: once the leading-order states in the degenerate $\{\ell=0,\ell=2\}$ subspace are correctly identified, the effective theory (implemented here with the graviton integrated out exactly, and expanded in $α$ only afterwards) reproduces \emph{all} of the $j=1$ Proca instability rates exactly, and it does so \emph{without} ever invoking the FKKS ansatz on which the full-theory calculation rests. Since it never relies on separability, the same approach applies, at least in principle, to rotating backgrounds and bodies that lack the hidden symmetries underlying that ansatz. The single ingredient beyond the far zone is a conservative worldline contact term, the static monopole response of the horizon in the parity-even $j=1$ Proca sector, which we fix by matching to the near zone. The same term shifts the fine-structure splitting of the bound states into exact agreement with the published Proca spectrum. In addition to providing a conceptually straightforward model of vector superradiance and resolving an apparent tension in the literature, we present this work to illustrate potential technical subtleties involving dissipative effects in point particle effective theories.

We show that the logotropic dark fluid, proposed as a single-fluid unification of dark matter and dark energy, is exactly dissipative unimodular gravity with pressureless matter and the logarithmic energy diffusion function $Q(a)=3A\ln a+Q_{c}$. The correspondence is exact at the level of the homogeneous background, rather than asymptotic, and introduces no parameters beyond those already present in either description. It provides a dynamical reinterpretation of the logotropic temperature $A$, whose origin was left open in the original proposal: up to the expansion rate, $A$ is the rate at which energy is diffused from matter into the geometric sector, $\dot Q=3AH$. The adiabatic sound speed of the effective fluid is $c_{s}^{2}=A/ρ$, where $ρ$ is the unimodular matter energy density, and reaches the speed of light at $a_{s}=a_{M}/2^{1/3}$; the matter energy density then vanishes and changes sign at $a_{M}$, which is precisely the scale factor at which the model is known to become phantom. Since $ρ$ coincides with the enthalpy density $ε+P$ of the logotropic fluid, the phantom branch is the branch on which the matter sector carries negative energy density and on which the apparent horizon entropy decreases. Finally, we show that a one-parameter saturating diffusion law removes these late-time pathologies while preserving the low-redshift phenomenology.

Motivated by the $2.6σ$ high-energy recoil event recently reported by the LUX-ZEPLIN (LZ) Collaboration, we consider an endothermic $Z^\prime$-portal Majorana dark matter framework and discuss the complementarity between the LZ event and LHC searches for a $Z^\prime$ resonance. As a concrete realization, we consider a gauged U(1) ${B-L}$ extension of the Standard Model. The phenomenology of the framework is essentially controlled by two free parameters: the U(1) ${B-L}$ gauge coupling $g_{BL}$ and the $Z^\prime$ boson mass $m_{Z^\prime}$. For a fixed $m_{Z^\prime}$, the observed dark matter abundance requires the dark matter mass to be near the $Z^\prime$ resonance, $m_{\rm DM} \sim m_{Z^\prime}/2$, and sets a lower bound on $g_{BL}$. Complementarily, LHC searches for a $Z^\prime$ resonance set an upper bound on $g_{BL}$. The parameter space allowed by the dark matter abundance and LHC constraints can account for the recent LZ event. The synergy between future $Z^\prime$ resonance searches at the High-Luminosity LHC and the LZ experiment may provide a test of this framework.

Free-floating planets (FFPs) may retain dynamical signatures of the mechanisms that eject them from their host systems. We integrate $10^6$ collisionless FFP test particles for $10^8$~yr in a static, phenomenological Galactic potential, comparing a mass-independent kick model with a mass-coupled prescription ($σ_{\rm CB}\propto M^{-0.15}$, $v_{\rm PL}\propto M^{-0.5}$) against a matched no-kick control. The imposed mass dependence is recovered at injection, with the combined-channel median coupled kick decreasing from $10.716$ to $0.708~{\rm km\,s^{-1}}$ across five mass bins---a factor of $\sim15.1$. A mass-dependent trend remains visible after $100$~Myr of Galactic propagation in the matched kicked-versus-control displacement, whose median decreases from $0.7001$ to $0.0539$~kpc across the same bins. The remaining numerical distinction is concentrated in this mass-resolved differential displacement rather than in the bulk phase-space moments: the final velocity dispersions of the null and coupled kicked populations are nearly identical, only a few percent of particles leave the adopted disk region, and the fraction of particles satisfying the formal Galactic-unbound criterion ($E_i>0$) remains negligible in every diagnostic we report. Comparing each kicked population against its matched no-kick control shows that much of the overall kinematic heating arises from the evolution of the initially warm, nonequilibrium disk rather than from the ejection kick itself, isolating the kick's smaller contribution.

Understanding tidal dissipation is a requisite step for explaining the evolution of systems such as short-period binaries. This understanding has not yet been achieved, and in fact there are many different approaches to modelling tides. By using Bayesian analysis on a system-by-system basis, we provide additional constraints on dissipation for 105 short-period Sun-like Kepler binaries. We account for period-dependent $Q$ and stellar evolution, and propagate observational uncertainties to uncertainties in our constraints. We find a group constraint of $\log Q_*' \approx 6.75$, with no apparent dependence on tidal period. We also do not detect mass dependence for $Q$. Our inferred prescription for the tidal dissipation successfully reproduces the unexpected overlap between almost perfectly circular and significantly non-circular orbits in binaries of Sun-like stars reported by arXiv:2112.05868.

We study the granular structure that emerges in a Fuzzy Dark Matter (FDM) halo formed through kinetic relaxation. After the system reaches a virialized core-halo structure, we separate the density field into a smooth spherical component and a residual density that contains the interference pattern characteristic of FDM halos. The power spectrum of this residual field shows a well defined dominant scale, different from the characteristic scale of the total density and of the smooth core-halo model. We compare this granular scale with a local de Broglie wave-lenght calculated from the velocity field obtained from the density current of the system. We find that both scales remain of the same order of magnitude, with the granular scale systematically smaller than the de Broglie wavelength. The radial behavior of the de Broglie wavelength also reveals a non-uniform internal structure, it decreases from the core and reaches its minimum near the transition between the solitonic core and the outer halo. These results provide a quantitative connection between density fluctuations, the local velocity field, and the core-halo morphology of FDM halos.

Entanglement entropy in holographic conformal field theories with boundaries of generic spacetime signature cannot be described entirely within the standard holographic duality to a real bulk spacetime. We show, both in static and time-dependent setups, that an exact match with the conformal field theory predictions in two boundary dimensions entails an extension of the dual spacetime to complex coordinates. As a consequence, relevant bulk objects such as Ryu-Takayanagi surfaces and branes are in general complex, yet anchored on a real asymptotic boundary preserving the physical meaning of field-theoretical quantities. We also provide a third numerical check of the holographic prediction with a two-dimensional system of free Gaussian fermions exhibiting the same asymptotic regimes across different entanglement phases.

The interpretation of high-energy nuclear recoil events in direct-detection experiments can depend sensitively on the poorly understood high-speed tail of the Galactic dark matter velocity distribution. This fact has been brought into sharper focus recently by an anomalous nuclear-recoil event at $E_R\approx248~\mathrm{keV}$ observed by the LZ experiment. If interpreted as caused by a dark-matter-induced recoil, kinematic constraints on many models imply this particle would have to emerge from the high-speed tail. Here, we re-assess this astrophysical uncertainty using Milky Way analogues from the IllustrisTNG and FIRE simulations. We find that the maximum laboratory-frame DM speed on June 16, when the event was observed, is $792.7^{+82.9}_{-95.6}\, \mathrm{km/s}$ (median and 95\% containment across simulations), with a median very close to the fiducial SHM value. Modelling the tail of the velocity distribution in three dimensions is complicated by the fact that these simulated dark matter halos are anisotropic and are generically seen to spin in the same direction as the baryonic disk. However, we find that this does not reduce the maximum laboratory-frame DM speed because the approximately Gaussian azimuthal velocity distribution is negatively skewed by this co-rotation, rather than shifted by it. We illustrate these results in the context of an inelastic dark matter interpretation of the LZ event.

In vacuum anti-de Sitter (AdS) space, the geometry admits a perfect tessellation by a geodesic network. This tessellation characterizes the background exactly, and a partial entanglement entropy (PEE) tensor-network toy model of AdS/CFT can be defined on it. It has so far been unclear whether this construction can be extended beyond vacuum AdS. In this paper we take the first step in this direction. We show that the exterior region of the Schwarzschild black hole and its Einstein--Rosen bridge are perfectly tessellated by a specific geodesic gas emitted from the boundary, so that Crofton reconstruction holds in these regions. We then prove that such a geodesic tessellation and the Crofton reconstruction it defines extend to more generic Riemannian manifolds. This allows us to construct a PEE tensor-network model of holographic duality on more generic geometric backgrounds. In the case of the PEE tensor-network model for the Schwarzschild background, we can concretely realize the Bekenstein--Hawking entropy, the Ryu--Takayanagi formula and the ER=EPR proposal. Our approach opens a new route towards holographic toy models beyond AdS/CFT.

Observations of the 21-cm signal can probe energy injection into the intergalactic medium arising from dark matter annihilation during cosmic dawn and reionization. For s-wave annihilation, the annihilation rate depends on the squared dark matter density, making the 21-cm signal sensitive to dark matter halo substructure. In this work, we extend the numerical method of DM21cm to address spatially inhomogeneous s-wave annihilation including subhalo effects, using semi-analytical treatment of SASHIMI-C. Our numerical results show that the projected HERA limit for the $γγ$ annihilation channel is stronger than the Leo~T bound within the dark matter mass range of $m_χ\leq 3\,{\rm keV}$, whereas the projected HERA limit for the $e^+e^-$ annihilation channel is the strongest among the existing bounds for $m_χ\sim 0.1$--$1\,{\rm GeV}$.

The dominant lattice approach to post-inflationary preheating and oscillon formation evolves an inhomogeneous inflaton field on a spatially homogeneous Friedmann-Lemaître-Robertson-Walker background, whose expansion is sourced by a volume-averaged energy density, while metric perturbations are neglected. We examine the consistency of this approximation with General Relativity. Using the linearized Einstein constraints, we show that the suppression of the Bardeen potential, characteristic of slow-roll inflation, disappears during preheating: once the first slow-roll parameter becomes of order unity, the metric and inflaton fluctuations enter at the same perturbative order. We further show that the scalar-field equation evolved in the fixed-FLRW prescription omits leading-order contributions generated by metric fluctuations. We then derive the proper-volume average of the ADM Hamiltonian constraint and show that it does not reduce to the Friedmann equation used in lattice simulations: the exact averaged constraint contains additional contributions from the spatial curvature, the variance of the local expansion, the shear, and metric corrections to the local energy density. Finally, we illustrate numerically, for Starobinsky and $α$-attractor models, that the metric contribution becomes comparable to the scalar-field contribution during the amplification stage. These results directly affect the standard lattice description of oscillon formation and motivate numerical relativity as a consistent framework for the nonlinear preheating problem.

In this paper, we provide a systematic construction of quantum modules associated with coadjoint orbits of asymptotic symmetry groups through the path integral quantization at one-loop order. In particular, for the orbits with Hamiltonians unbounded from below, we show that an appropriate choice of integration contour defines a convergent Euclidean half-line path integral. The reference state associate with the orbit is determined by the path integral of the geometric action on the corresponding coadjoint orbit. The coadjoint module is therefore spanned by the reference state and its descendants. We apply this formalism to the Virasoro and BMS$_3$ groups and derive the coadjoint modules corresponding to all constant orbits. We also compute the characters of all constant Virasoro and BMS$_3$ coadjoint orbits by counting the states within the modules, and the results agree with the corresponding computations from the path integral of the geometric action with a periodic Euclidean direction.

We compute the fully renormalized one-graviton-loop contribution to the self-mass of a massive scalar field in de Sitter space. The computation is performed using dimensional regularization and the divergences are absorbed by BPHZ counterterms. This self-mass can be used to study one-loop quantum-gravitational corrections to the dynamics of massive spectator scalars in inflation.

One revisits the Entangled Relativity theory framework, embedding it in a larger set of theories. From their scalar-tensor reformulation, these theories admit General Relativity spacetime solutions as solutions with the same matter content, if this matter obeys an "intrinsic decoupling" condition. One shows that a set of matter Lagrangians satisfying this condition is completely characterized by the way they depend on the metric tensor. One then shows that it is possible to define a perfect fluid Lagrangian fulfilling the intrinsic decoupling condition up to 1PN order. Specifying to weak field spherical stars suggests that Entangled Relativity and its proposed generalization are worthy alternatives to General Relativity. Indeed, the obtained numerical values of the Eddington parameters abruptly satisfy the known observational constraints. However, the non strict compliance of the theory with conservation laws demands to reconsider the link between observational data and the parameters for a definitive clarification of this point.

The non-adiabatic heating of the slow Solar Wind (SW) remains an open problem, with wave--particle interactions as a primary candidate mechanism. Novel in situ Parker Solar Probe (PSP) observations reveal strongly perpendicular anisotropic velocity distribution functions (VDFs), called "hammerhead", correlated with intense wave activity. These VDFs are systematically measured at the Heliospheric Current Sheet (HCS), making the hammerhead an important kinetic signature of the slow SW. In this work, we employ a fully kinetic particle-in-cell approach, complemented by a linear Vlasov solver to cross-validate the simulation results, to investigate the stability of these VDFs, the timescales over which they evolve, and their interaction with plasma waves. Our main findings indicate that the hammerhead distribution is primarily susceptible to drift-type instabilities, while energy is nonlinearly transferred back to the plasma through a combination of Landau and cyclotron resonances, resulting in net heating in the parallel direction, preferentially energizing the beam proton population. Crucially, these nonlinear interactions do not drastically alter the morphology of the distribution. This suggests the possibility that the hammerhead may be generated locally within the HCS in the inner heliosphere and subsequently advected outward, where it is eventually measured by PSP. This work lays the ground for future investigations into the kinetic physics of the HCS.

The Baade-Wesselink method, while theoretically applicable for calibrating the distance scale via Cepheids, is not currently employed in the cosmic distance ladder. There are various versions of this method. In all these approaches, the projection factor used to convert the radial into the pulsation velocity remains the limiting quantity. By comparing for the first time simultaneous cross-correlated optical and H-band radial velocities of five Cepheids, we aim to better understand the geometric part of the projection factor that is directly linked to the limb darkening of the stars. The five Cepheids were observed with the HARPS-N and GIANO-B instruments mounted at the Telescopio Nazionale Galileo in the GIARPS configuration. A two-parameter linear fit was applied to the simultaneous radial velocity measurements of each star in order to extract the amplitude ratio of both curves (fVH) as well as the difference in mean velocities. We find a mean value of fVH of 1.056 with a root mean square over the five stars of 0.016, which means that the V-band radial velocity amplitudes are around 5% larger than the ones obtained in the H band. In addition, we find that the H-band radial velocity curves have an average (i.e., a gamma-velocity) of about 1 km/s blueshifted compared to the visible ones, except for one star, X Cyg, which has a blueshift of 0.4 km/s. At first order, the fVH values are directly linked to the ratio of limb darkening coefficients in both bands (or equivalently the ratio of geometrical projection factors). The fVH values are found to be consistent with expectations from static stellar atmosphere models. This work shows that the differential limb darkening of Cepheids in visible and H bands, and consequently the geometrical part of the projection factor, follows what is expected from stellar atmosphere models.

WISE J0855-07 is the coldest known brown dwarf (estimated Teff~250 K), offering a rare opportunity to probe atmospheric physics in the temperature and mass regime that overlaps directly with exoplanets. At these temperatures, modest perturbations to the thermal structure and chemical abundances can produce measurable changes in the emergent mid-infrared spectrum, making time-resolved spectroscopy a powerful way to test whether the atmosphere is longitudinally and temporally homogeneous. Using James Webb Space Telescope NIRSpec/G395M time-series spectra spanning ~3 to 5.2 μm over 11 hr, we analyze every third spectrum from the dataset with a series of time-resolved atmospheric retrievals using the Brewster retrieval framework. Using this approach, we model epoch-to-epoch changes in the atmospheric state that drive the observed variability, including the thermal structure and key molecular abundances. From the time-series retrievals, we find that the primary source of the observed spectral variability is driven by the variations in the thermal structure, which range from ~1 to <100 K from epoch to epoch, particularly between the pressures of ~0.4 and 10 bar. In addition, changes in the abundances of CO, and possibly PH3 and CO2, further modulate the spectrum within specific molecular features. These measurements provide a retrieval-based view of atmospheric variability in an ultracold, planet-like object, directly constraining how thermal and chemical structure evolve on observable timescales.

The [C/N] abundance ratio is a powerful age indicator for giant stars, enabling age estimates for spectroscopic samples where traditional methods are limited. We calibrate a multivariate [C/N]-age-[Fe/H] relationship using 9,122 giant stars observed by Kepler, with asteroseismic ages and APOGEE DR17 abundances. The calibration is performed separately for lower red giant branch (LRGB), upper RGB (URGB), and red clump (RC) stars. We validate the relationships using independent samples from K2, TESS, and open clusters, finding good agreement with reference ages, particularly for LRGB stars, with typical precision of ~30% for ages between ~2 - 10 Gyr. The performance degrades for URGB and RC stars and low metallicities, likely due to extra mixing processes, for young (<2 Gyr) and old (>10 Gyr) stars, where the [C/N]-age correlation weakens. We show that the [C/N]-based ages reproduce known Milky Way features, including the age distribution across the [alpha/Fe]-[Fe/H] plane and the flaring of the Galactic disc. Compared to other chemical clocks, [C/N] provides more robust and precise age estimates within its domain of validity. Our results demonstrate that [C/N], combined with metallicity, is an effective empirical tool for deriving stellar ages of giant stars from spectroscopic surveys, particularly for LRGB stars with [Fe/H] > -1, enabling Galactic archaeology studies beyond the reach of current asteroseismic samples.

We investigate the weak and strong gravitational lensing of a dyonic black hole in Kalb-Ramond gravity. After fixing the asymptotic normalization, we distinguish the effective charge governing the local null trajectories from the global angular identification associated with Lorentz-symmetry breaking. In the weak-deflection regime, we evaluate the Gaussian curvature explicitly and apply the Gauss-Bonnet theorem with a perturbed ray boundary, recovering the complete second order mass contribution. Independent calculations based on the orbit equation, the turning point integral, and Fermat's principle reproduce the same bending angle. In the strong-deflection regime, Tsukamoto's method yields closed expressions for both strong-deflection coefficients, with exact charge dependence. We derive finite-distance lens equations and the associated image positions, magnifications, flux ratios, and differential arrival times, retaining the physical winding condition. Shadow sizes inferred from observations of Sgr~A$^*$ and M87$^*$ yield conditional charge bounds, complemented by an estimate from S2 precession. We further construct combinations of strong-lensing observables that separate the effective charge from the conical parameter within the model: angular separation and relative brightness remove the explicit winding dependence, while a timing ratio incorporating an independent distance estimate isolates the conical deformation.

We present a Bayesian framework for converting time-resolved spectroscopy into rotation-inferred regional spectra and atmospheric constraints for variable brown dwarfs. We derive an analytic mapping framework with evidence-optimized regularization and uncertainty propagation by marginalizing over physical parameters and model complexities. We provide methods for selecting characteristic spectral end-members from the inferred surface maps, and highlight the advantage of analyzing these rotation-inferred regional spectra over the disk-integrated time-resolved observations, while explicitly accounting for the geometric degeneracies inherent to rotational mapping. We apply this framework to published JWST/NIRSpec rotational monitoring of Luhman 16B and SIMP 0136. For both objects, we identify dominant spectral regions and retrieve regional variations in cloud structure, thermal gradients, and chemistry that are consistent with cloud radiative feedback. In addition, we demonstrate the importance of limb darkening in deriving surface maps. These results establish a statistically controlled method for linking rotational spectral variability to atmospheric heterogeneity and enable future rotational mapping and regional atmospheric studies of giant planet atmospheres.

Context. The HERMES spectrograph is a high-resolution, fibre-fed optical spectrograph of the 1.2m Mercator telescope operated from the Roque de los Muchachos observatory in Spain. HERMES started its scientific operations in June 2009 and has been the workhorse instrument since then. Regular instrument updates have been crucial. They have helped to ensure the continued provision of high-quality spectra. This will continue both now and in the future. Aims. With this contribution we review over 16 years of HERMES operations and we launch and introduce the archive to the interna- tional community at large. We describe the overall performances of the HERMES spectrograph and list the most important instrument upgrades since the start of the operations. We release about 150 000 high-resolution spectra to the community and describe global properties of the datarelease. We use a standard propriety period of 1 year with some exceptions. Methods. We used the German Astrophysical Virtual Observatory (GAVO) DaCHS platform to present the archive in a Virtual Ob- servatory (VO) compatible form with both an access via a dedicated webinterface, and via VO-compliant tools like PyVO, TOPCAT, Aladin etc. We illustrate the use in several worked-out examples to search and download the fully wavelength-calibrated, cosmic- cleaned and barycentric corrected 1D spectra. Results. With this contribution we provide the needed information of the data product and offer a reference paper for the users of the HERMES archive.

Remnant planetary systems around massive white dwarfs ($M_{\rm WD} > 0.8\,{\rm M}_\odot$) are intrinsically rare and remain poorly characterized. As the evolutionary endpoints of intermediate-mass B- and A-type stars, these white dwarfs provide valuable constraints on the formation and survival of planetary systems around higher-mass progenitors. In the absence of large, dedicated spectroscopic surveys, extremely-low-resolution Gaia XP spectra provide a powerful means of identifying candidate metal-polluted white dwarfs. We obtained follow-up observations with low-resolution optical spectroscopy (R=500-4000) to search primarily for Ca II H & K absorption in massive, metal-polluted white dwarf candidates selected from Gaia XP spectra to increase the sample of massive remnant planetary system hosts among objects with effective temperatures below $\sim15{,}000$ K. We find that Gaia XP spectra recover metal-polluted white dwarfs efficiently, confirming 82$\pm$5% recovery of photospheric metals (59 of 72 targets) in high-confidence candidates of our sample (with classifier probability $P_{\rm DZ} > 0.65$). However, Gaia photometric masses derived from $G$, $G_{BP}$, and $G_{RP}$ broad-band photometry are not sufficient to identify the most massive systems, as reliable mass determinations require detailed metal-enriched atmospheric fits. We present a selection of cool white dwarfs confirmed to be both massive and metal polluted, demonstrating that Gaia XP spectra can substantially expand the sample of white dwarf exoplanet hosts. Our search led to the discovery of a new transiting debris system, SDSS J1624+5404, the 21st published system to date and eighth to show periodic transits.

The recent observation of the high-energy nuclear recoil event LZ230616 with a recoil energy around 248 keV provides an interesting possibility to probe inelastic doublet dark matter (iDM). However, the electroweak doublet DM scenarios face strong constraints from solar DM capture for DM masses around the TeV scale which give rise to correct thermal relic density. In this work, we revive the inelastic doublet DM (iDM) scenario via type-II seesaw. In particular, we consider an inert lepton doublet (ILD) DM. While the minimal ILD scenario gives the correct relic abundance around the TeV scale, it is strongly constrained by direct detection and solar DM capture. In the type-II seesaw, the presence of the scalar triplet generates the required mass splitting and provides additional annihilation channels, allowing the correct relic abundance for much larger DM masses. The larger DM mass also helps evade the solar capture and indirect detection constraints. Additionally, the scalar triplet gives sub-eV neutrino masses required by the oscillation data.

Spectroscopic variability is detected in brown dwarfs across all spectral types, suggesting atmospheric patchiness in brown dwarf atmospheres. We present JWST/NIRSpec time series observations of the T8.0 planetary-mass companion Ross 458C. We compared our derived spectral variability and light curve to those obtained using HST/WFC3 observations more than 7.5 yr before and published by Manjavacas et al. (2019). We found that the light curve of Ross 458C is remarkably similar in the two epochs in terms of shape and variability amplitude potentially created by stable weather patterns. We measured a rotational period of 11.57+\-0.09 hr, demonstrating that the previously reported HST/WFC3 period of 6.75+\-1.58 hr is most likely a second-order harmonic produced by an unresolved double-peaked rotational modulation, likely due to the higher uncertainties of the HST/WFC3 light curve and the short time baseline of those observations. We measured the variability amplitude in the white light curve created using only the wavelength range covered by HST/WFC3 (1.10-1.63 micron), obtaining a value of 1.47+\-0.18%, which is consistent with that measured in the HST/WFC3 light curve.

Planetary impact rates are difficult to infer from observations alone because impacts are rare, observational records are target-dependent, and converting observed flashes, bolides, and craters to an intrinsic impact rate depends on uncertain selection effects and conversion parameters. Building on the simulations in Paper I, we examine whether observational systematics can explain the order-of-magnitude mismatch between observed and modeled impact rates on Earth, and whether comparable discrepancies extend to other Solar System bodies. We convert 12 observed impact records for Earth, the Moon, Mars, and Jupiter to a common pre-atmospheric impact rate for $D>10$ m, propagate uncertainties through the conversion chain, and compare the resulting rates with the intrinsic rates derived in Paper I. We find discrepancies for Earth (observation-to-model median ratio $2.2-21.0$), the Moon ($3.4-132.1$), Mars ($14.2-118.6$), and Jupiter ($2.6-47.7$), with the dominant source of the discrepancy differing by body. The simulated Jupiter-family comet (JFC) contribution substantially reduces the Earth discrepancy, suggesting that an additional dynamical source may help explain the gap. The lunar records disagree with each other by two orders of magnitude, with the discrepancy dominated by size-extrapolation uncertainties. The Mars mismatch is dominated by crater-to-impactor conversion. The Jupiter comparison depends mainly on uncertainties in the inferred number of bound impactors and in the observational completeness thresholds. Further investigation of this mismatch requires incorporating cometary modeling and tighter constraints on size-extrapolation scaling and improved observational completeness.

Among all gravitational solutions, traversable wormholes stand out as truly fascinating, yet within general relativity, they almost always demand exotic matter that necessarily violate null energy requirement. The inclusion of matter-geometry coupling in modified gravity theories provides a viable platform where wormholes remain open which are supported by effective gravitational field. We therefore examine the structure and properties of slowly rotating traversable wormholes using the $f(R,T)$ framework. We formulate stationary wormhole models coupled with the anisotropic fluid and show that they are regular, horizon-free, approach a flat spacetime geometry at large distances, and satisfy the flare-out requirement at the throat. Our results indicate that the required matter meets both the null and strong energy conditions, demonstrating that rotating wormholes do not necessarily require unconventional sources. We further study particle trajectories, frame dragging phenomena, and non-geodesic behavior resulting from matter-geometry coupling, alongside the weak-field and lensing effects caused by the rotation. Our results establish the potential astrophysical viability of rotating wormholes in $f(R,T)$ gravity.

The DeWitt boundary condition can be implemented in the Lorentzian path integral of minisuperspace quantum cosmology by summing only over non-singular paths. We give a general definition of the resulting DeWitt kernels, together with explicit rules for constructing them, and evaluate them exactly. The lapse integral over the positive half-line yields the Dirichlet Green function of the Wheeler--DeWitt operator, whereas the integral over the whole real line yields the Dirichlet group-averaging kernel; both vanish when either endpoint lies at the singularity. Since the minisuperspace actions are at most quadratic, all lapse integrals are performed in closed form without saddle-point approximations. We obtain the kernels for the closed universe without cosmological constant, where the whole-real-line kernel vanishes identically, for the flat de Sitter universe, and, in terms of Airy functions, for the closed and open de Sitter universes. Throughout, the DeWitt condition is imposed as the boundary condition at the singularity, which selects a self-adjoint constraint operator on the half-line and fixes the kernels uniquely, including their normalization.

Static, asymptotically flat, non-Schwarzschild black holes in four-dimensional Einstein--Weyl gravity have previously been constructed by numerical shooting, while the local field equations admit horizon and asymptotic expansions to all orders. We give a computer assisted existence proof for a non-Schwarzschild solution whose dimensionless horizon radius is one in units of the massive spin-two scale, with parameters close to the previously reported numerical branch. The exterior is divided into a convergent horizon series domain, a compact core enclosed by a parameter dependent Taylor model with directed rounding, and an infinite asymptotic domain treated as a centered stable manifold fixed point problem. The resulting five-dimensional matching map between the core and tail is continuous on a rigorously specified box. After exact rational preconditioning, the signs on opposite faces satisfy the hypotheses of the Poincaré--Miranda theorem and therefore certify a matching zero. The solution has a regular nondegenerate horizon, no additional exterior horizon, vanishing Ricci scalar, and nonvanishing Ricci tensor. The proof establishes existence, but not uniqueness of the matching zero.

We investigate a quantum cosmological model within the framework of Einstein-Æther gravity. The model consists of a positively curved FLRW Universe whose matter content is described by pressureless dust, in the presence of a positive cosmological constant $Λ$. We first perform a classical Hamiltonian analysis utilizing Schutz's variational formalism, constructing the phase space and deriving the dynamics of the scale factor. Notably, we identify specific initial conditions that lead to an inflationary expansion, which are extracted directly from the underlying quantum dynamics. Subsequently, we quantize the model following Dirac's formalism, obtaining the Wheeler-DeWitt equation for the wave function of the Universe. We solve this equation numerically and investigate our results using the WKB approximation to compute quantum tunneling probabilities $TP_{WKB}$ alongside an integrated tunneling probability $TP_{int}$, the expectation value of the scale factor coming from the many-worlds interpretation of quantum mechanics, and the corresponding Bohmian trajectories. Finally, we analyze how these tunneling probabilities are influenced by variations in the fundamental parameters of the theory ($Λ, σ, β$) and the energy of the dust fluid $E$. Our results indicate a higher probability for the quantum birth of the Universe in a parameter regime characterized by larger values of $Λ, σ$, and fluid energy $E$, together with a smaller value of $β$.

We measure the intrinsic alignment (IA) of galaxy multiplets with the large-scale tidal field traced by galaxy positions in DESI Data Release 2. Using the BGS, LRG, and ELG samples spanning $0.01 < z < 1.6$, we optimize the scales which define multiplets in each sample to minimize measurement noise. We measure multiplet tidal alignment $\mathcal{E}_+$ on scales beyond 100 $h^{-1}$Mpc in all samples, and detect alignment over 200 $h^{-1}$Mpc, up to 4.5$σ$ in the highest LRG redshift bin. We additionally present the multiplet shape-shape autocorrelation, $\mathcal{E}_{++}$, which is independent of galaxy bias and provides a consistency check of our NLA (nonlinear alignment) model. We do not detect a baryon acoustic feature in the projected estimator. We also find the alignment strength of multiplets is correlated with redshift and galaxy morphology. Multiplet alignment offers direct access to the tidal shear field in all galaxy samples, even where individual galaxy alignment cannot, and extends IA detection to the largest scales yet probed.

Eclipsing binaries provide precise constraints on stellar properties and evolution, making those hosting $β$ Cep pulsators particularly valuable for characterising massive pulsating stars. In this paper, thirteen eclipsing binaries with massive primary components are spectroscopically and photometrically analysed to derive the orbital and stellar parameters, and infer their possible evolutionary status. The systems were spectroscopically observed using SALT HRS, HERMES, CHIRON and a spectrograph at Skalnate Pleso Observatory (SPO), and photometrically observed using TESS. Radial velocities and atmospheric parameters are determined, binary systems are modelled, and their absolute parameters are derived using appropriate modelling tools. The rotational properties, circularisation, and synchronisation of the systems are also investigated, and the general properties of the sample are discussed. The sample shows one slow rotator, two circularised and synchronised fast rotating systems, as well as five circular and five eccentric systems with asynchronous fast rotation. The systems are predominantly SB1 or SB2 with faint companions, resulting in dynamical mass estimates at $5$ -- $12\%$ precision and radius estimates at $1.5$ -- $3.9\%$ precision. The secondary components appear to cut across a wide mass spectrum ranging from low-mass to intermediate mass systems. The eccentricity of the systems shows certain trends with the projected rotational velocity ($v \sin i$) although there is no universal correlation between them. Also, there could be circularisation without co-rotation or synchronisation even for circularised short-period close binary systems.

RR Lyrae are pulsating variable stars tracing old ($>10$ Gyr) stellar populations, and exhibit a strong mid-infrared Period-Luminosity (PL) relation that can be calibrated with known parallaxes to infer distances. Here we present Period-Luminosity relations and distance moduli for three isolated globular clusters in the Large Magellanic Cloud: Reticulum, NGC 1841, and NGC 1466. Our analysis uses legacy \textit{Spitzer Space Telescope} images obtained by the Carnegie RR Lyrae Program, and an internally self-consistent sample restricted to RRab stars, with cluster membership confirmed using Gaia DR3 proper motions and photometry. In the Spitzer 3.6~$μ$m band, we simultaneously fit a PL for these clusters using a slope derived from Galactic Globular Clusters, yielding extinction-corrected distance moduli of $18.47\pm0.09$ mag for Reticulum, $18.29\pm0.09$ mag for NGC 1841, and $18.61\pm0.09$ mag for NGC 1466. The latter two are the first RR Lyrae PL-based distance moduli for these clusters, and all three are consistent with literature values from other techniques. Additionally we fit a PL with slope as a free parameter, and find that this LMC-derived PL is consistent with that derived from Galactic GCs. Simultaneously fitting a PLZ for the three clusters yields a metallicity coefficient $c= -0.03\pm0.05~\mathrm{mag}~\mathrm{dex}^{-1}$ which can be considered a negligible dependence of the PL on metallicity ($|c| <0.1$ mag dex$^{-1}$). Modelling an intrinsic width, $W$, to the PL/ PLZ yields a consistent value $W\approx0.1\pm0.02~\mathrm{mag}$, suggesting intrinsic width is not driven by metallicity.

We construct a new class of smooth, finite-energy solitons in the bosonic $SU(2)\times U(1)$ Weinberg-Salam theory, which we dub $electroweak$ $balls$. Their localization mechanism is analogous in spirit to that of $Q$-balls: the charged vector fields possess a harmonic time dependence while the energy-momentum tensor remains time independent. We explicitly construct both spherically symmetric electric-type solutions and axisymmetric magnetic-type solutions, and show that they form families characterized by a finite frequency interval, a mass gap, and a two-branch structure. These configurations provide electroweak counterparts of Proca-Higgs balls, with the vector-boson masses generated by the Higgs mechanism rather than introduced explicitly. The construction is not tied to the measured parameters of the Standard Model. More generally, it applies to bosonic electroweak-type sectors with different gauge couplings, Higgs self-coupling and symmetry-breaking scale, and hence potentially very different characteristic particle and soliton mass scales. For the families studied here, we do not find solutions at the measured Standard Model couplings and mass ratios.

We investigate the stability and localization properties of Minkowski, de Sitter (dS), and anti-de Sitter (AdS) thick branes generated by a complex scalar field $Φ$. The scalar self-interaction potential contains a temperature parameter $a$. As $a$ approaches its critical value, the imaginary part of $Φ$ becomes double-kinked and the energy density splits into two peaks, indicating the formation of two sub-branes. The analysis of linear scalar, vector, and tensor perturbations shows no signs of instability in the scalar and vector sectors, while the factorization of the tensor perturbation equation excludes tachyonic tensor modes. The graviton zero mode is localized on the Minkowski and dS branes but is not normalizable on the AdS brane. We further study a real test scalar field $Ψ$ with a coupling function $F(R)$ between its kinetic term and the spacetime curvature. The scalar zero mode can always be localized on the Minkowski and dS branes, with a continuous gapless spectrum of scalar Kaluza--Klein (KK) modes. Massive scalar resonances emerge near the critical value of $a$ for suitable values of $β$. Increasing $β$ produces more resonances and prolongs the lifetimes of the lower resonances, while their time evolution exhibits the characteristic decay of metastable modes. For the AdS brane, the scalar zero mode is also localized, whereas the divergent effective potential at the boundaries traps the massive scalar KK modes as bound states, yielding a discrete mass spectrum.

Exoplanets orbiting active stars offer distinct challenges for atmospheric characterization with the JWST. Among such worlds, the hot Saturn WASP-52b (Teq $\sim$ 1300 K) orbits an active K-dwarf that complicates transmission spectroscopy via stellar contamination. Here, we present the first JWST NIRSpec G395H (2.8-5.2 $μ$m) limb-averaged transmission spectrum of WASP-52b obtained through the JWST Morning/Evening Program (GO-3969), which aims to measure limb asymmetries across a sample of hot giant exoplanets. Our spectrum reveals the first detection of CO2 in WASP-52b's atmosphere (ln B = 54 / >10$σ$), with a retrieved abundance of log CO2 = -5.09 (+1.09/-1.14), and confirmation of H2O (ln B = 5.9 / $\sim$3-4$σ$), with an abundance of log H2O = -3.41 (+1.04/-1.04). We find a steep near-infrared slope that cannot be explained solely by H2O absorption, necessitating unocculted starspots (ln B = 5.7 / $\sim$3-4$σ$), though with properties that vary across our data reductions. The shape and amplitude of the molecular bands additionally suggest high-altitude (<10 mbar) inhomogeneous clouds covering $\approx$40 $\pm$ 20% of the terminator (ln B = 1.9 / $\sim$2.5$σ$), which provides evidence for the morning-evening terminator differences that are consensus predictions of general circulation models. WASP-52b's atmospheric metallicity can be sub-solar, solar, or super-solar, due to order-of-magnitude uncertainties in the molecular abundances caused by degeneracies between compositions, clouds, and starspots. However, chemical equilibrium retrievals provide a similar statistical fit while favoring a tighter constraint with a super-solar metallicity (M/H = 14.8 (+12.1/-5.9) $\times$ solar). These results highlight that chemical detections and aerosol properties may still be recovered for planets orbiting active stars via transmission spectroscopy.