高能暂现源 · 每日文献综述

We investigate neutron star matter with hyperons within a density-dependent relativistic mean-field framework using Bayesian inference, considering three composition scenarios: purely nucleonic matter, hyperonic matter under SU(6) flavor symmetry, and hyperonic matter under SU(3) symmetry with free vector-sector parameters. The analysis incorporates constraints from empirical nuclear matter properties, theoretical inputs at low densities, and multimessenger observations of neutron stars. We find that the SU(6) scheme, grounded in the quark model and isospin counting rule, leads to a significantly softer equation of state. In contrast, the additional flexibility of the SU(3) framework enhances vector repulsion and yields a comparatively stiffer equation of state consistent with observational bounds across the explored parameter space; in particular, the posterior distributions favor values of the vector coupling ratio $α_v$ lower than the SU(6) limit $α_v = 1$. These differences are reflected in neutron star observables, including mass--radius relations, tidal deformabilities, direct Urca thresholds, and oscillation properties, all of which remain compatible with current constraints within the SU(3) scenario. We further examine structural signatures through the curvature of the mass--radius relation and find that, although hyperon-rich configurations can induce noticeable variations, such features depend sensitively on the stiffness of the equation of state and are therefore not universally robust indicators. Bayesian model comparison further shows that present constraints do not meaningfully discriminate between the purely nucleonic and SU(3) hyperonic scenarios, while providing positive, but not decisive, evidence against the more restrictive SU(6) framework.

Accretion-induced collapse (AIC) of a rotating oxygen-neon-magnesium white dwarf (WD) is an alternative channel of neutron-star formation, in which a mass-accreting star near the Chandrasekhar mass collapses instead of being disrupted thermonuclearly. If the progenitor WD is sufficiently magnetised, it can drive magnetorotational outflows analogous to those of magnetorotational supernovae and may serve as a site for rapid neutron-capture ($r$-process) nucleosynthesis. We post-process tracer particles from five three-dimensional general-relativistic neutrino-(magneto)hydrodynamic AIC simulations, spanning four initial rotation rates, with the WinNet nuclear reaction network. Ejecta mass, the fraction of matter reaching nuclear statistical equilibrium, and the mass ejected beyond the iron group all increase monotonically with rotation rate, with magnetic fields amplifying these trends. The slowest-rotating model synthesises essentially only iron-group material, while the most rapidly rotating and magnetised model reaches the second $r$-process abundance peak at mass number $A \approx 130$, with a trace, non-robust signal up to $A \approx 244$. The corresponding $^{56}$Ni mass rises from $0.007$ to $0.014 M_\odot$, lower than representative yields for core-collapse supernovae and hypernovae by factors of five to more than forty, implying a correspondingly faint radioactively powered component. Contrary to the picture established for magnetorotationally driven supernovae, the heaviest ejecta do not track the polar outflow: they instead reside in equatorial-to-mid-latitude, moderate-entropy lobes, while the polar column is itself a local minimum in some heavy elements. We conclude that rapidly rotating, magnetised AIC events could contribute to the Galactic yields of trans-iron and weak $r$-process nuclei, although none of our models produces a robust third $r$-process peak.

The quantum memory burden effect can suppress the late-time Hawking evaporation of primordial black holes (PBHs), allowing PBHs below the standard evaporation threshold of approximately $10^{15}\,\mathrm{g}$ to survive until the present epoch and potentially contribute to the dark matter abundance. We investigate primary and secondary neutrino emission from memory burdened Bardeen and Kerr PBHs, including Galactic and extragalactic fluxes and the effects of memory suppression, Bardeen regularization, and Kerr rotation. We constrain their abundance using observations from IceCube, Super-Kamiokande, and ANTARES, together with the projected sensitivities of IceCube-Gen2, GRAND200k, and Hyper-Kamiokande. We find that Bardeen regularization and Kerr rotation produce qualitatively different effects. Increasing the Bardeen parameter suppresses the Hawking temperature and neutrino flux, thereby weakening the abundance constraints. In contrast, rapidly rotating Kerr PBHs that retain a significant residual spin at the onset of the memory burdened phase can exhibit enhanced neutrino emission and substantially stronger constraints. Increasing the memory burden suppression index $k$ reduces the flux normalization but also allows lighter and hotter PBHs to survive, shifting the relevant signal toward higher energies. Consequently, HESE provides the leading sensitivity for weak suppression, whereas IceCube-Gen2 and GRAND200k become particularly important for stronger suppression. These results demonstrate the complementarity of current and future neutrino observations in probing memory burdened PBHs and the effects of regular geometry and rotation on their evaporation.

Binary population synthesis (BPS) codes are extremely useful tools for investigating both the end-to-end lives of binary stars as well as a myriad of astrophysical phenomena observed in the Universe. Given the widespread use of BPS in modern astrophysical research, it is imperative to systematically compare BPS codes across the spectrum of computational efficiency, flexibility, and physical realism to gauge their consistency and robustness. In this work, we perform BPS using three modern codes---the rapid code $\texttt{COSMIC}$, the hybrid code $\texttt{METISSE}$ integrated into $\texttt{COSMIC}$, and the detailed code $\texttt{POSYDON}$---on three single-metallicity populations of identical initial binaries, ensuring consistent choices in physical parameterizations where possible. Investigating the final population of merging binary black holes (BBHs) as a test case, we find stark differences in the properties, formation pathways, and progenitors across the three codes. In an initial population of one million binary stars at $0.01 Z_\odot$, each code results in $\sim 5,000-9,000$ BBHs that merge within a Hubble time. However, only one initial binary becomes a BBH merger in all three codes, and $\lesssim 14 \%$ of BBH progenitors consistently merge in two codes. Binaries that become BBH mergers in two codes often go through different evolutionary pathways and result in different final properties. In short, the codes are inconsistent in predicting BBH merger properties, even for identical initial binary systems. Our results highlight the need for systematic comparisons of BPS techniques, for a deeper understanding of physical and computational differences between BPS codes, and for caution in over-interpreting the results from any BPS code. (Abridged)

As the LIGO-Virgo-KAGRA Collaboration's (LVK's) gravitational-wave transient catalog grows, we are learning a wealth of information from the population properties of binary black hole mergers. Events in the catalog are represented with posterior samples describing the astrophysical parameters for each event. Population studies combine these samples to measure the distribution of astrophysical parameters such as black hole masses and spins. However, the posterior-sample representation of each event is only approximate. We construct a mock population with masses drawn from an astrophysically motivated distribution with sharp features. Using this, we demonstrate that when <inline-formula><mml:math><mml:mrow><mml:mo>≳</mml:mo><mml:mn>300</mml:mn></mml:mrow></mml:math></inline-formula> events are combined, even with each event's posterior represented by <inline-formula><mml:math><mml:mn>1</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mn>4</mml:mn></mml:msup><mml:mo>-</mml:mo><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mn>4</mml:mn></mml:msup></mml:math></inline-formula> samples, the numerical error can become large enough that the resulting population inference is unreliable. We consider two solutions. In the short term, we show that nested samples (already produced by LVK analyses) can be used to more accurately describe each event in population studies. But this will only grant a temporary reprieve until the nested-sample representation becomes inadequate. In the longer term, we propose to represent each event with a normalizing flow. In order to represent each event with sufficient accuracy, each normalizing flow can be used to generate an arbitrarily large number of new posterior samples with a significantly reduced computational cost relative to traditional sampling methods. When compared to nested sampling, our normalizing flows produce posterior draws with a median of <inline-formula><mml:math><mml:mo>≍</mml:mo><mml:mn>80</mml:mn><mml:mo>%</mml:mo></mml:math></inline-formula> fewer likelihood evaluations per sample, while also providing greater opportunity for parallelization. We believe refinement of normalizing flow architectures and training techniques in future works could further reduce this per-sample cost significantly.

The detection of a stochastic gravitational-wave background (SGWB) is a primary science objective for the Laser Interferometer Space Antenna (LISA). However, extracting these signals is difficult because both the signal and the instrumental noise are stochastic and overlapping in the millihertz band. In this work, we present a Bayesian framework for the joint estimation of LISA noise and SGWB signals. Our approach models the LISA instrumental noise using flexible log-penalized splines, employing a roughness penalty to prevent overfitting while maintaining computational efficiency. For the SGWB, we compare a power-law model with a spline-based model and study how the choice of signal model and noise prior affects signal recovery and detection. Using simulated LISA data, we find that the power-law model gives tighter estimates when the signal follows the assumed shape. However, it fails to recover a localized spectral feature that is not described by a power law, causing the signal to be absorbed by the instrumental-noise spline. The fully spline-based model is less restrictive and successfully recovers such features. We also find that stronger prior information about the test-mass noise helps reduce the degeneracy between the noise and SGWB models at low frequencies, improving signal detection. These results reflect a single trade-off: added model flexibility reduces sensitivity when the assumed signal shape is correct, and prevents bias when it is not.

We present a combined photometric and orbital period analysis of the contact binary systems OV Leo and V339 Leo using ground-based observations together with TESS photometry. The light curves were modeled with the BSN software through a Markov Chain Monte Carlo approach, providing physical estimates of the system parameters and their uncertainties. OV Leo is analyzed photometrically for the first time, while V339 Leo is reexamined using new observations and an updated modeling methodology. The light curve analysis show that both targets are W-subtype contact binaries in shallow-contact configurations. The O'Connell effect detected in V339 Leo is reproduced with a cool starspot model, whereas no spot is required for OV Leo. Three-dimensional geometric models further indicate that OV Leo undergoes total eclipses, while V339 Leo exhibits partial eclipses. Orbital period analysis based on eclipse timing extractions reveals opposite long-term period variations in the two systems, suggesting ongoing mass transfer under the assumption of conservative mass transfer. The absolute parameters were derived using the Gaia parallaxes, the photometric light curve solution, and standard astrophysical equations.

The recent evidence for a stochastic gravitational wave (GW) background at nano-Hz frequencies from pulsar timing arrays (PTAs) provides a strong science case for exploring cosmological histories and phase transitions at the Square Kilometer Array Observatory (SKAO). The latter cosmological events are of primary interest for physics of the early Universe associated with out-of-equilibrium and relaxation phenomena in the vicinity the quantum chromodynamics (QCD) epoch as well as those originating from dark sectors or other phenomena beyond the Standard Model of particle physics. Such a novel GW portal provides a complimentary access to particle physics phenomena that have so far escaped detection at particle colliders, and also probes fundamental aspects of out-of-equilibrium dynamics beyond the perturbation theory and their cosmological implications. This chapter aims at elucidating most interesting physics cases, theoretical models and approaches, as well as cosmological scenarios that are of particular relevance for future GW measurements at SKAO. We elaborate on how such measurements can deepen our understanding of particle interactions and violent processes in the early Universe, and discuss possible competitive advantages and complementarity of SKAO in this research compared to other experiments.

Coronal mass ejections (CMEs) are among the primary drivers of space weather disturbances at Earth, yet their early propagation in the low corona remains poorly constrained owing to occultation and projection effects inherent to coronagraph observations. Coronal dimmings offer an alternative diagnostic to infer CME propagation direction directly from the low corona. We present the DIRECD CME Direction Catalog, a unified dataset of three-dimensional CME propagation directions derived via the DIRECD (Dimming Inferred Estimation of CME Direction) method, which reconstructs CME cone geometry from SDO/AIA 211 Å coronal dimming observations. The catalog comprises 64 events spanning 2010-2026, combining 31 Solar Cycle 25 (2021-2026) events with 33 events from prior studies. For each event we report the 3D propagation direction, 2D inclination angles, angular width, and cone height. Statistical analysis reveals a systematic asymmetry in low-coronal CME propagation: meridional inclinations exhibit a systematic tendency toward latitude-dependent deflection, with poleward deflections more pronounced at higher source latitudes, while equatorial inclinations show no significant dependence on source longitude. This is consistent with low-coronal CME trajectories being governed primarily by local active-region magnetic topology, with the large-scale coronal field and heliospheric current sheet assuming a progressively dominant role at greater heliocentric distances. Incorporating DIRECD-derived propagation directions into CME arrival forecasts improves predictions of geomagnetic storm intensity, raising the correlation with observed storm strength from r = 0.58 to r = 0.70 when combined with CME speed. The DIRECD software, catalog, and all associated data products are publicly available to support space weather research.

The appearance of hyperons in the core of neutron stars generally softens the equation of state (EOS), posing a longstanding challenge to the existence of observed two-solar-mass compact stars. We investigate whether repulsive interactions mediated by a dark-sector vector portal can provide an additional source of high-density pressure and thereby modify the structure of hyperonic compact stars. The baryonic sector is described within the modified quark-meson coupling (MQMC) model, in which the octet baryons are treated as confined relativistic constituent-quark systems interacting self-consistently through the $σ$, $ω$, and $ρ$ fields within a mean field approximation. The dark sector consists of a fermionic dark matter coupled to baryonic matter through a neutral vector mediator $Z^\prime$, generating an additional repulsive contribution to the dense-matter EOS. We investigate the resulting equation of state, mass--radius relation, tidal deformability, and moment of inertia. The resulting mass--radius relations satisfy the observational bounds from massive pulsars, including PSR J0740 + 6620, with maximum neutron star masses reaching approximately $2 M_{\odot}$. The resulting changes in tidal and rotational observables provide additional avenues for testing the dark-sector interaction through multimessenger observations.

Westerlund 1 (Wd 1) is the closest supermassive star cluster to the Sun, with over 100,000 stars of all spectral types down to brown dwarfs. This population strongly heats the surrounding interstellar medium (ISM), making Wd 1 a key site to study stellar feedback on intracluster gas. We present the most detailed X-ray study to date of its diffuse emission, aiming to separate and quantify the point-source contribution to the true diffuse emission. We analysed 36 Chandra ACIS-I observations within an 8x8 arcmin window. After removing 4922 point sources with ACIS Extract using energy-dependent PSF models and adaptive 99% enclosed-energy masks, we subtracted PSF-wing contamination and corrected for background, then applied adaptive smoothing in soft, medium, and hard bands. Spectral fitting suggests a shocked thermal plasma, with diffuse X-rays correlating spatially with massive stars. The core (Region #2) fits an APEC+PSHOCK model, with temperatures of 1.81+/-0.24 and 4.11+/-1.98 keV and a 6.7 keV Fe K-alpha line. The outer Region #1 shows charge-exchange emission, fitting a CXE+NEI model with softer temperatures of 0.27+/-0.04 and 1.09+/-0.05 keV. Column densities range from 1.84-2.24x10^22 cm^-2, and the total (0.5-8.0 keV) diffuse luminosity is ~9.6(+/-0.3)x10^33 erg/s. Near the core, hard emission likely arises from thermalised Wolf-Rayet winds and wind-wind collisions, softened by adiabatic expansion and turbulent mixing with cooler ISM. The soft component extends farther out, possibly from CXE in lower-extinction regions. No non-thermal contribution is found. A cluster-wind model predicts a luminosity ~2.2 above that observed, consistent with a low-density, partially evacuated intracluster medium. The resulting wind-to-X-ray efficiency, eta ~4.3x10^-6, is about two orders of magnitude below Cygnus OB2, yielding comparatively subluminous diffuse X-ray emission.

Ultralight scalar dark matter can make space-based gravitational-wave detectors respond through both the scalar charge of freely falling test masses and scalar-induced changes of local solid length scales. Existing space-detector forecasts usually model the former as a center-of-mass force, while ground-based interferometer studies show that scalar fields can also act through material and optical-path transduction. We ask which part of a local material response survives after one-way Doppler measurements are assembled into delayed time-delay-interferometry observables. To this end, we formulate center-of-mass motion and endpoint-size breathing in a common link-response notation for LISA-, Taiji-, and TianQin-like detectors. The main result is a projection rule: in the equal-arm, identical-endpoint, common-field limit, endpoint breathing enters Michelson-$X$ as a common-mode link perturbation and is removed from the retained channel. Its leading leakage is controlled by finite scalar wave vector, unequal or time-dependent arms, nonidentical endpoint response, or auxiliary readouts, and carries extra geometric and delay suppressions beyond the local size response. We then give reproducible noise, sensitivity, and network-combination formulas, and quote multi-mission improvements only under explicit independent-stream and scalar-coherence assumptions. The result provides a controlled baseline for deciding when test-mass breathing can be neglected and when instrument-specific material response must be modeled.

Astrophysical binaries formed by a stellar-mass compact object and a massive black hole are among the most promising sources for future space-based gravitational-wave detectors. These extreme mass-ratio inspiral (EMRI) systems are tracked coherently over more than $10^{5}$ orbits, encoding detailed information about strong-field gravity. Translating a detection into physical parameters requires models of comparable precision. One outstanding difficulty is the treatment of transient orbital resonances. In this work we address the problem at the level of the Koopman operator, where the waveform is promoted to an observable and the evolution over one radial cycle is a linear operator. Removing the fast timescale without a singularity at a crossing is then a matter of choosing a function of that operator. We demonstrate the approach on a Kerr geodesic driven through the 3:2 crossing by a modelled forcing term. There the coefficient of the standard near-identity transformation diverges, while the finite-window generator attains its analytic bound to better than one part in $10^{6}$. Averaging over twice the crossing duration recovers the resonant jump with its predicted magnitude and phase dependence.

We constrain the large-scale isotropic random component of the Galactic magnetic field using the Planck reconstruction of the 408 MHz synchrotron sky. Our analysis simultaneously fits the random-field structure, the synchrotron contributions of the coherent field and local foregrounds, and isotropic and dipolar offsets. A new element of the analysis is the use of excess polarized emission at 30 GHz to model local foregrounds, allowing us to retain 97% of the sky without absorbing these structures into Galaxy-wide features of the magnetic field. Across variations in the coherent-field model, cosmic-ray electron distribution, sky mask, and field profile, we consistently find that the dominant random-field component is a vertically compact disk with a local rms strength of about 4 $μ$G and a 1/e scale height of approximately 1 kpc, substantially thinner than in most previous models. An annular enhancement in the inner Galaxy improves the fit to the data, whereas we find no evidence for either a large-scale spiral pattern or a thick random-field disk. The fits also yield an intensity monopole of 4-7 K, whose possible origin we discuss. We quantify the implications of the inferred random field for the angular smearing of ultrahigh-energy cosmic rays. Compared with previous models, the sky-median smearing angle is smaller by up to a factor of 1.7, and by up to 2.4 in individual directions.

In this work, we present results from general-relativistic radiative-transfer calculations of black hole accretion and jet launching to reproduce the observed properties of the M\,87 jet at sub-parsec scales. For the first time, in the simulations we have included a blob component at the launching region of the jet that allowed us to reproduce the quasi-simultaneous low-energy spectral energy distribution ($10^{10} \text{ Hz} \leq ν\leq 10^{16} \text{ Hz}$). Moreover, we obtain a better fit of the synchrotron emission in the self-absorption region ($ν\leq 10^{11} \text{ Hz}$), showing that the inclusion of a blob component in our radiative transfer calculations results in a flatter spectrum ($α_{22-86\ \text{GHz}}=0.08$). Additionally, our simulations improved the accuracy of the observed morphology of M\,87's jet, matching the data up to a distance of 0.6 mas from the core at 86 GHz. Our results reproduce the edge-brightened structure up to $\sim1.3$ mas, i.e., in a more extended region compared with previous studies, with a brighter southern edge. The obtained synthetic image of the jet reproduces additional observed knots along the southern edge.

We simulate a self-interacting three-flavor neutrino system within a core-collapse supernova using a hybrid classical-quantum algorithm on a qutrit computer. Based on the Dirac-Frenkel evolution equations, we employ a variation of the quantum-assisted simulator to calculate the system's time evolution operator by performing qutrit Hadamard tests to find expectation values of unitary operators in the Hamiltonian. The time evolution simulation is then done classically. We find that the hybrid algorithm produces results comparable to an exact numerical integration out to times of <inline-formula><mml:math><mml:mrow><mml:mi>t</mml:mi><mml:mo>≍</mml:mo><mml:mn>30</mml:mn><mml:msubsup><mml:mrow><mml:mi>ω</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula> with time step <inline-formula><mml:math><mml:mrow><mml:mi>δ</mml:mi><mml:mi>t</mml:mi><mml:mo>=</mml:mo><mml:mn>0.005</mml:mn><mml:msubsup><mml:mrow><mml:mi>ω</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula>, where <inline-formula><mml:math><mml:msub><mml:mi>ω</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math></inline-formula> is the energy scale of the single neutrino vacuum oscillations. We discuss the lessons learned in simulating neutrino systems using this hybrid quantum-classical algorithm, along with the advantages it offers over quantum Trotterization.

We calculate the <inline-formula><mml:math><mml:mrow><mml:mi>f</mml:mi></mml:mrow></mml:math></inline-formula>-mode frequency of quark stars using the full general relativity method, and evaluate the tidal overlap with an analogy method incorporating effective general relativistic corrections. We verify the universal relations obtained from conventional neutron stars in the case of quark stars, including the <inline-formula><mml:math><mml:mrow><mml:mi>f</mml:mi><mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow><mml:mrow><mml:mn>1.4</mml:mn></mml:mrow></mml:msub><mml:mi>─</mml:mi><mml:mi>Λ</mml:mi></mml:mrow></mml:math></inline-formula> and <inline-formula><mml:math><mml:mrow><mml:msub><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mrow><mml:mi>f</mml:mi></mml:mrow></mml:msub><mml:mi>R</mml:mi><mml:mo>/</mml:mo><mml:mi>M</mml:mi><mml:mi>─</mml:mi><mml:mi>Λ</mml:mi></mml:mrow></mml:math></inline-formula> relations, and explore the cases with different values of parameters of the quark star equation of state. Since quark stars have significantly smaller radii compared to neutron stars in the low-mass range, the <inline-formula><mml:math><mml:msub><mml:mi>ω</mml:mi><mml:mi>f</mml:mi></mml:msub><mml:mi>R</mml:mi><mml:mi>─</mml:mi><mml:mi>Λ</mml:mi></mml:math></inline-formula> relation differs between neutron stars and quark stars. This difference has an impact on the dynamical tide, which is the lowest-order effect we know of that can distinguish quark stars and neutron stars from the gravitational wave during the inspiral phase. We calculate the tidal dephasing caused by this effect using the post-Newtonian method and estimate that <inline-formula><mml:math><mml:mrow><mml:msubsup><mml:mrow><mml:mn>34</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>16</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>12</mml:mn></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula> events for the Einstein Telescope and <inline-formula><mml:math><mml:msubsup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>6</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>5</mml:mn></mml:mrow></mml:msubsup></mml:math></inline-formula> events for Cosmic Explorer are required to distinguish between quark stars and neutron stars at the population level.

In the past few decades, the waveform community has made advances in producing waveforms that span the inspiral-merger-ringdown of comparable-mass-ratio black hole binaries using advances in post-Newtonian and numerical relativity (NR) theory along with state-of-the-art gravitational wave models. Current methods in NR have shown progress toward producing stable simulations reaching mass ratios of <inline-formula><mml:math><mml:mrow><mml:mn>1</mml:mn><mml:mo>∶</mml:mo><mml:mn>100</mml:mn></mml:mrow></mml:math></inline-formula>; however, the computational cost becomes prohibitively expensive as the mass ratio and the length of the simulation increases. Meanwhile, the gravitational self-force (GSF) community has developed waveform models that not only generate extreme mass ratio inspiral waveforms, but also generate near-equal-mass-ratio waveforms with high fidelity. To assess the limits of both the GSF and NR waveforms and alleviate the computational costs of NR, we present hybridized GSF-NR waveforms for nonspinning binary black hole systems in which GSF provides the inspiral, and NR the merger and ringdown. The hybrid waveforms are generated from a set of 68 nonspinning NR waveforms from the SXS catalog with mass ratios spanning <inline-formula><mml:math><mml:mrow><mml:mn>1</mml:mn><mml:mo>∶</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math></inline-formula> to <inline-formula><mml:math><mml:mrow><mml:mn>1</mml:mn><mml:mo>∶</mml:mo><mml:mn>20</mml:mn></mml:mrow></mml:math></inline-formula> and include the (2, 2), (2, 1), (3, 3), (3, 2), (4, 4), (4, 3), and (5, 5) spin-weighted spherical harmonic modes. In this paper, we will highlight a selection of these hybrid waveforms and examine the error in the hybridization procedure. We will investigate the impact of subdominant modes on the accuracy of the hybrid waveforms by performing mismatch comparisons with surrogate models. To address the feasibility of hybridizing GSF inspirals with short-duration, high-mass ratio NR waveforms, thereby alleviating computational costs, we will discuss the relationship between mass ratio and the placement of the matching window, which can be used to predict the necessary and optimal number of NR cycles that contribute to the hybrid waveform.

An introductory review is provided for those who are interested in exploring applications of qubits and other quantum excitations to the detection of dark matter (and any other physics beyond the Standard Model). Topics covered include the fundamental properties of qubits, the excitation mechanism of qubits due to the electric field induced by dark matter (with attention to the effects of the coherence of dark matter), the dynamics of coupled qubit-cavity systems modeled by the Jaynes-Cummings framework, and the influence of noise and decoherence (especially Markovian noise described by the Lindblad equation). In addition, the article introduces essential concepts in quantum sensing, including the operator-sum representation and positive operator-valued measures, the Cramér-Rao bound, the standard quantum limit and the Heisenberg limit, and the potential enhancement of sensitivity to dark matter achievable with entangled states. Throughout, these topics are discussed with particular emphasis on their application to the detection of wave-like dark matter.

We report the non-detection of stellar light associated with the dark galaxy candidate Cloud-9. Ultra-deep imaging obtained with HiPERCAM at the Gran Telescopio Canarias (GTC) reaches surface-brightness limits of 31.4 and 31.0 mag/arcsec$^2$ in g and r, respectively, approximately ten times deeper than previous deep imaging of the region. No stellar emission is detected within the central 1'$\times$1' ($\sim$1.3$\times$1.3 kpc) region of Cloud-9. Assuming an old, metal-poor stellar population, these limits imply a stellar surface mass density of no more than $\sim$0.01 M$_\odot$/pc$^2$ and an upper limit on the total stellar mass of 1.6$\times$10$^4$ M$_\odot$. This independent constraint from integrated light complements previous limits based on resolved-star counts and strengthens the case for Cloud-9 as a candidate starless galaxy.

We investigate how tidal locking affects the planetary dynamo and the magnetospheres of Earth-like planets orbiting the habitable zones of M dwarfs. We couple an empirical stellar wind model with two distinct planetary dynamo paradigms, direct rotational scaling and energy-flux scaling, using a Constant Time Lag (CTL) model to simulate continuous tidal spin-down until synchronization. We model two hypothetical planets based on a highly dissipative Modern Earth and a less dissipative, rapidly rotating Early Earth representative of the Paleoarchean. Our results show that tidal locking acts as a severe negative feedback on planetary magnetism across both paradigms, where the dipolar field frequently collapses before full tidal synchronization is reached. Essentially, a shielded atmospheric environment around M dwarfs requires a host massive enough ($\geq 0.32 M_\odot$) to place the HZ at wider orbital distances, sparing the planet from the sub-Alfvénic environment, and the internal tidal dissipation of the planet must be sufficiently low to prevent rapid rotational decay. For mid-to-late M dwarfs, the inevitable tidal locking and the extreme stellar wind pressures result in a total collapse of the magnetic shield, reducing the likelihood of atmospheric protection to essentially zero across the habitable zone.

We formulate a global optical-area method for shadows of static, spherically symmetric black holes. For the metric \(ds^{2}=-A(r)dt^{2}+B(r)dr^{2}+C(r)dΩ^{2}\), spherical sections of the optical geometry have area \(\mathcal{A}_{\rm opt}=4πC/A\). A null ray with impact parameter \(b\) can cross a spherical section only if \(b^{2}\leq C/A\). The capture threshold is fixed by the infimum of \(C/A\) on the connected interval between the observer and the black hole horizon. When attained at an interior point, the infimum gives \(b_{\rm sh}^{2}=\min(C/A)\), while a static observer outside the controlling minimum, on the inward-sky branch, measures \(\sin^{2}α_{\rm sh}=\mathcal{A}_{*}/ \mathcal{A}_{\rm opt}(r_{\rm o})\). The usual photon-sphere equation follows when the minimum occurs at a smooth interior point. Exponential instability additionally requires the minimum to be nondegenerate. The local optical-radius and photon-sphere formulas are established results. Our contribution is to organize them into an observer-to-horizon global selection rule that compares all stationary candidates and relevant endpoint limits. The radial function \(B(r)\) does not affect the shadow angle, although it enters the coordinate-time instability rate, whose numerical value also depends on the normalization of the static time coordinate. We derive compact first- and second-order formulas for deformed metrics, demonstrate candidate comparison with a synthetic two-minimum profile, and apply the construction to Reissner--Nordström, Bardeen, charged dilaton, and Kottler black holes. An explicit transformation of the charged-dilaton example from a nonareal to an areal radial coordinate verifies radial-coordinate invariance, while the Kottler example probes a nonasymptotically flat static region.

Africa has deep and diverse traditions of astronomical knowledge, ranging from archaeological astronomy, pharaonic stellar timekeeping, and manuscript astronomy in Timbuktu and the Sahel, to ecological seasonal astronomy in southern Africa and calendrical computation in the Ethiopian tradition. These multiple epistemic traditions form part of a long intellectual history that precedes and intersects with contemporary astronomy on the continent. In the context of this long-standing intellectual heritage, an important question arises regarding the contemporary circulation of African astronomical knowledge within the global scientific system. This study therefore examines where African astronomical knowledge is produced, validated, and circulated in modern scholarly communication. Using bibliometric data from the Web of Science Core Collection, our analysis investigates publication and citation patterns in the research area Astronomy and Astrophysics between 2000 and 2025, with particular attention to the publication venues of African scholars. The findings highlight a critical paradox: while African researchers are active contributors to global astronomical discovery, the intellectual capital generated through this work is largely stored, validated, and circulated through publication systems located outside the continent. This pattern reflects broader asymmetries within global scholarly communication, where dominant publishing infrastructures shape visibility, citation impact, and authority. By applying a decolonial lens to metrics such as citation impact and ownership, the paper calls for a critical reassessment of the academic practices that sustain epistemic coloniality. It concludes that achieving scientific equity requires a strategic shift in publication choices to build and fortify a sovereign African knowledge archive.

Previously, it was shown that static black hole event horizons cannot exist in time-dependent backgrounds without becoming naked singularities. In light of this, we are left with the question ``how does a black hole horizon evolve in an expanding universe, then?'' Here we offer a solution to this puzzle by showing in full generality that black hole apparent horizons tend to become comoving, thus confirming the necessity of a cosmological coupling and raising intriguing possibilities for the early growth of black holes.

A broad class of dark matter (DM) models predicts the existence of sub-structures residing in DM haloes on sub-resolvable angular scales. Techniques to extract such a generic feature from diffraction-limited observations are lacking. In this work, we propose a model-independent 'super-resolving' method applicable to strong gravitational lens systems that is fully data-driven, without reference to any lens models. This method relies on a specific way of applying the optical Liouville theorem across multiple scales in the imaging data, a technique we refer to as geometrical-duality. We test this method using realistic simulations and apply it to a 'constellation' consists of 11 compact star clusters seen in two giant arcs in the lensing cluster SMACS0723 imaged by JWST as a proof-of-concept. We find reasonable self-consistency with the expectation of non-detection given the statistical sensitivity, except for one pair of star clusters. Such an outlier can be explained in the context of CDM as sub-haloes lensing in the mass range $M_{\rm sub} = 10^8 - 10^9\,M_\odot$, for which the corresponding Einstein radius is smaller than the diffraction limit of JWST.

Every traversable wormhole reported so far in static (2+1) gravity coupled to nonlinear electrodynamics has come from a power-Maxwell Lagrangian L propto |F|^k restricted to k=1/2, always forcing the cosmological constant to a fixed sign or zero. We show these restrictions are artefacts of that single choice, not physical requirements, and give a complete classification of static traversable wormholes in this theory. Of the three mutually exclusive electromagnetic configurations compatible with the symmetry, the radial electric branch admits no throat for any Lagrangian or Lambda. In each remaining branch, azimuthal electric and magnetic, the field equations admit exactly two regimes: either the redshift function is fixed, leaving the shape function b(r) completely free with Lambda absorbed without constraint; or the redshift is generic, in which case b(r) becomes fixed instead. We solve both regimes in closed form in both branches, and show that fixing the Lagrangian to any single power k forces Lambda nonzero and determines b(r) up to finitely many constants: this freedom requires the Lagrangian to be genuinely unrestricted. One azimuthal-electric family reproduces the static BTZ mass function, turning the vacuum black hole into a wormhole once sourced by the nonlinear field. Applied to the unique conformal power-Maxwell theory, k=3/4, previously known only as a radial-branch charged black hole, the same Lagrangian yields genuine wormholes in the azimuthal and magnetic branches, showing the electromagnetic configuration, not the Lagrangian, decides between a horizon and a throat; Born-Infeld electrodynamics admits no throat in any branch.

We prove that black-hole isospectrality between linearly independent solutions follows whenever radiative metric and matter perturbations are reconstructed from complex master variables obeying a closed, complex-linear system with complex-linear boundary conditions. If a phase rotation maps one parity sector to the other, then the even- and odd-parity QNM spectra coincide, and the perturbations are parity isospectral. A broad class of chiral-aligned theories satisfies these criteria. As an application, we demonstrate that subextremal Kerr--de Sitter black holes are parity isospectral.

We investigate the dynamical instability and gravitational collapse of charged, spherically symmetric anisotropic matter configurations within $f(R,\mathcal{L}_{m})$ gravity. The analysis focuses on the combined effects of anisotropic pressure, perturbations, electric charge, and modified-gravity source terms on the stability of compact objects. A specific equation of state is adopted to relate the static and perturbed variables through the adiabatic index. Using a perturbation scheme, we derive the modified hydrostatic equilibrium and collapse equations and obtain instability constraints in both Newtonian and post-Newtonian regimes. The results show that the stability of the system is governed by the competition between inward gravitational attraction and outward pressure support. In addition, the dark source terms generated by the non-minimal matter-geometry coupling modify the collapse conditions and can enhance the stability of the charged fluid. These findings provide a useful framework for understanding the evolution and collapse of dense self-gravitating compact objects in non-minimally coupled gravity.

We investigate the inflationary dynamics of a spectator massive vector field with a non-minimal curvature coupling in de Sitter (dS) and quasi-de Sitter (qdS) backgrounds, focusing on the transverse and longitudinal sectors. By solving the mode equations with Bunch-Davies initial conditions, we compute the spectral energy densities and quantify the deviations between the exact dS approximation and the slow-roll-corrected qdS evolution. We find that the coupling parameter xi significantly affects the evolution of the effective mass, the mass-crossing condition, and the behavior of the longitudinal mode. In particular, increasing xi suppresses the vector fluctuations and reduces transient tachyonic effects. We further follow the evolution of the modes into the radiation-dominated era, showing how the inflationary initial conditions determine the subsequent spectral energy densities. Our results identify the parameter regime in which the dS approximation provides an accurate description and determine when slow-roll corrections become relevant.

Newtonian mechanics is usually written on a spacetime of fixed geometry. Here we build that geometry, introducing a propagator and a bilinear form only as the description demands. Within this reconstruction the Principle of Inertia emerges as a theorem rather than an independent postulate. Inertial motion is blind to the scale of the form and to the torsion the propagator defines, and that blindness is a geometric precursor of the \emph{universality of free fall}, before gravity enters. Newton's Second Law is a compatibility between two derivatives along a curve. The force exceeds the mass times the lowered acceleration by an exact term, and the law survives arbitrary torsion. Requiring force-free motion to be inertial along curves parametrised by arc length restricts the torsion to be totally antisymmetric. The remaining torsion is a three-form which we postulate the particle carries along its worldline. Its contraction with the velocity annihilates that velocity, so the supplementary condition of spinning-particle mechanics holds identically, and we propose that contraction as a classical spin. The algebra is familiar from relativistic spin hydrodynamics; the assignment, to the best of our knowledge, has not been proposed elsewhere. Since inertial motion resolves neither the mass nor the spin, the predictive content lies in the transport law we postulate, which turns the spin against a parallel-transported frame at a rate fixed by the acceleration alone and by no coupling constant. That rate becomes a laboratory number only once the arc-length parameter is identified with a clock, which we leave open. The dynamics asks non-degeneracy of the form, so this spacetime is not Newton--Cartan's Galilean one, and gravitation lies outside the construction. We prove every mathematical result, make three constitutive postulates and one physical conjecture.

Exceptional control of systematic effects is required in order to achieve unbiased cosmic shear two-point correlation function measurements with the next generation of galaxy imaging surveys, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). One critical challenge is accurately modeling the point-spread function (PSF), as errors in PSF estimation can introduce spatially correlated biases in galaxy shape measurements. The LSST Science Pipelines, which will be used to process Rubin data, include an implementation of the PIFF (PSFs in the Full Field of View) package originally developed for, and demonstrated to perform well on, DES-Y3 and Y6 data. In this work we use semi-realistic image simulations, mimicking LSST observing conditions in $i$-band over 100 square degrees, to perform an end-to-end test of the Rubin PSF modeling pipeline. PSF model residuals are quantified using both second- and fourth-order moment parameters and performance is evaluated, for both LSST year 1 and year 10 depth, with a series of diagnostic tests. We find that the additive bias contribution from PSF modeling errors to the non-tomographic cosmic shear data vector is well below 30% of the cosmic shear uncertainty estimated from our analytic covariance matrix. Though our simulations exclude several known effects that may further challenge PSF modeling, these results demonstrate promising performance from PIFF on LSST-like data and provide an early benchmark for ongoing PSF validation efforts for LSST weak lensing analyses.

Since the first gravitational-wave (GW) detection of September 14, 2015, and with hundreds of gravitational-wave sources identified by the LIGO-Virgo-KAGRA network, GW have produced many important results in astrophysics and fundamental physics. Along with planned new data takings, current detectors will be upgraded, and new projects, such as the Einstein Telescope and Cosmic Explorer, are under study. Among noises limiting low frequency sensitivity, vibroacoustic noises are particularly important. In this work, we focus on the gravity gradient noise (also called Newtonian noise) of acoustic origin, which refers to the small fluctuations in the gravity field resulting from the acoustic pressure field present in the experimental areas of the detector. The induced noise is quantified in an original way, using a detailed numerical acoustic model of the experimental room, when the pressure field is excited by the air conditioning system. The method is used for Virgo, but it can be easily extended for future detectors and used to guide the design of caverns and experimental areas.

We report on numerical simulations of critical phenomena in the collapse of axisymmetric vacuum gravitational waves, adopting families of initial data that, to the best of our knowledge, have not been used in this context before. Like Teukolsky waves, the data are based on linear wave solutions to the Einstein equations. We follow Nakamura's construction and encode the wave content in the extrinsic curvature rather than the spatial curvature, which leads to several simplifications when the data are "dressed up" so that they satisfy the nonlinear constraint equations. We are able to fine-tune these data to the onset of black hole formation slightly better than in our previous simulations, allowing us to observe and examine one more echo in the approximately self-similar threshold solution. Our findings are consistent with earlier studies: while we find threshold solutions that are approximately discretely self-similar, the self-similarity is not exact, and we find no evidence for a unique critical solution. We discuss common features between the different threshold solutions, including the appearance of alternating maxima in the direction of the poles and the equator.

We investigate the relativistic dynamics of network nonlocality in general $n$-local networks with chain and star topologies using the Unruh-DeWitt detector model. We show that the relativistic degradation of network nonlocality is strongly governed by the underlying topology. While chain networks suffer an irreversible sudden death of non-$n$-locality under relativistic motion, star networks exhibit remarkable resilience against relativistic decoherence. Most strikingly, a minimal star network with three peripheral nodes exhibits a remarkable sudden death-sudden birth transition of network nonlocality as the acceleration increases. This reentrant behavior reveals a dual role of the Unruh effect: it can both suppress and protect network nonlocality, offering a new perspective on the relativistic effects of acceleration on quantum networks. For larger star networks ($n>3$), non-$n$-local correlations persist over the entire acceleration regime. These insights provide valuable conceptual guidance for the structural optimization and design of acceleration-resilient architectures for future relativistic quantum communication and sensing protocols.

We determine the complete solution set of the conformally flat isotropic pure Lovelock field equations for every order $N\ge2$ and every admissible dimension $d\ge2N+1$. Conformal flatness and pressure isotropy combine into a single identity that factorises exactly, splitting the solutions into two branches. The first is the constant-density Schwarzschild interior, which persists at every order with both metric potentials keeping their Einstein form. The second has no Einstein counterpart and is governed by the single dimension--order parameter $k=(d-2N)/[4(1-N)]$; we obtain its physically admissible orbit in explicit closed parametric form, both potentials included. A phase-space analysis on the projective line shows that no solution of this branch has a pressure-free boundary at finite radius, so only the Schwarzschild branch can describe a bounded star. The second instead loses all memory of its central data and relaxes onto a pure Lovelock isothermal sphere with $ρ\propto r^{-2N}$, a higher-curvature analogue of the singular isothermal halo, which we show to be the attractor of the whole family, approached at the closed-form rate $λ_*=-(d-2)/(d-2N)$ and with limiting equation of state fixed by $(d,N)$ alone. We prove that $p/ρ$ increases monotonically outward there, and that of the two regular-centre orientations only one is admissible. Since $k$ is rational the spatial potential is algebraic of degree $u+v$, where $2k=-u/v$; radical inversion is guaranteed for degree at most four, while four representative cases have full symmetric Galois group.

In this work, we investigate the cosmological reconstruction of $f(Q, T)$ gravity, where $Q$ is the non-metricity scalar and $T$ is the trace of the energy-momentum tensor. We consider the functional form $f(Q,T)=f(Q)+λT$ and reconstruct explicit forms of $f(Q)$ corresponding to the $Λ$CDM expansion history in Friedmann-Lemaître-Robertson-Walker (FLRW) universe. By employing the matter conservation equation and expressing the cosmological quantities in terms of $Q$, the reconstruction problem is formulated as a first-order linear differential equation for $f(Q)$. Analytical solutions for $f(Q)$ are obtained for various matter configurations, including dust-like matter, a perfect fluid with equation-of-state parameter $ω=-1/3$, and a nonisentropic perfect fluid with a time-dependent barotropic index. Additionally, an e-folding formulation of the reconstruction is considered to examine the cosmological evolution in terms of the e-folding parameter. The resulting forms of $f(Q)$ confirm that the $Λ$CDM expansion history can be successfully realized within the $f(Q,T)$ framework across diverse matter sectors.

Static black holes in conformal Weyl gravity differ from their Einstein counterparts in a simple but important way: the Mannheim--Kazanas geometry is encoded in a Bach-flat lapse function whose radial dependence is richer than that of Schwarzschild--de Sitter. We study the de Sitter branch of this solution in the Schwarzschild gauge, keeping the characteristic linear term together with the quadratic de Sitter term. In the branch continuously connected to the positive-mass Schwarzschild--de Sitter spacetime, a regular static region between a black-hole horizon and a cosmological horizon exists precisely when \[ -\frac{1}{3}<βγ<\frac{2}{3}, \qquad 0<κ<\frac{1+3βγ}{27β^{2}}. \] In this window the singularity at the origin is hidden, the two positive horizons obey $0<r_b<3β<r_c$, and the limiting endpoint is the Nariai geometry. The thermodynamic interpretation is subtler than the root structure: the two horizons generally have different temperatures, and the static patch has no asymptotic region that would select a unique normalization of time. We therefore compare the Killing, Bousso--Hawking normalized, Tolman local, and effective two-horizon temperature conventions, and we compute the corresponding Wald entropy for the pure Weyl-squared action. The result is a local horizon thermodynamic description that keeps the geometric facts separate from the ensemble-dependent choices needed for any global first law.

In a recent paper \cite{Chu:2026dhx}, the quantum stability of the fuzzy sphere was established at large but finite $N$. In addition, a tadpole was identified for the scaling fluctuation mode of the matrix geometry. In this paper, we show that the tadpole generates a positive surface tension and tends to contract the sphere if the horizon is left isolated. However, when the horizon is coupled to gravity, the tadpole requires the bulk geometry to adjust according to the junction condition of general relativity. Assuming a static, spherically symmetric and non-singular vacuum interior, pure de Sitter space is selected. The matching also fixes an intriguing large-$N$ soldering relation between the de Sitter time inside and the Schwarzschild time outside. Potential cosmological implications are discussed.

Vertical gradient of mean turbulent electromotive force (expressed by the dynamo coefficient, alpha, caused by the penetrating convection into the tachoclines of Sun-like stars leads to the non-propagating alpha-mode patterns, which result in the periodic variations of magnetic field horizontal components. The aim of the paper is to study the influence of the latitudinal variation of the dynamo coefficient on the linear dynamics of large-scale waves in the overshoot layers of the tachoclines in Sun-like stars. We use the linear magnetohydrodynamic (MHD) equations with the dynamo coefficient in a simple rectangular geometry. It is shown that the vertical gradient of the alpha coefficient has the same appearance in the induction equation as the Coriolis force in the momentum equation. Therefore, the latitudinal variation of alpha parameter excites new large-scale waves similar to the Rossby waves on a rotating sphere. The dispersion properties of the waves depend only on vertical and latitudinal gradients of the alpha parameter, therefore the modes are basically different from the ordinary dynamo waves. The alpha_theta waves may have either prograde or retrograde propagation depending on the signs of the gradients. The time scales of the waves may vary from hundreds of days to tens of years in various parameters of the solar tachocline. These waves are coupled with the Rossby waves on a rotating sphere in the existence of the large scale magnetic field, which may lead to the mutual transformation of convective and rotation energies.

We study a minimal effective field theory description of the three-dimensional Lyman-$α$ forest using the Sherwood and Sherwood--Relics hydrodynamical simulations. We model the Lyman-$α$ flux auto-power spectrum and its cross-correlation power spectrum with the dark matter density field using a tree-level bias model supplemented by the leading counterterms and stochastic contributions. We find that the model describes the simulated auto- and cross-power spectra well up to $k_{\mathrm{max}}=3\,h\,{\rm Mpc}^{-1}$ and $k_{\mathrm{max}}=2\,h\,{\rm Mpc}^{-1}$, respectively. We analyse simulations spanning multiple redshifts, reionisation histories, box sizes and resolutions to assess the robustness of the model. Even within this minimal model, we find strong parameter degeneracies, highlighting the need for independent constraints on nuisance parameters in applications to real data analyses. The redshift evolution of the linear bias parameters is consistent with previous simulation-based studies and is driven primarily by the evolution of the effective optical depth, $τ_{\mathrm{eff}}$. We also find that the inferred parameters are affected by the resolution of the simulation and, to a lesser extent, by the simulation box size. We also explore the impact of reionisation history, finding that variations mainly affect the linear bias parameters over the range of scales considered. Moreover, we find empirical correlations between model parameters and the Lyman-$α$ forest density bias that show some scatter, indicating that one single parameter is not enough to determine the model parameters. Finally, we compare our results with theoretical predictions from analytical models of the Lyman-$α$ forest.

Previously, it was shown that the interplay between the gravitational memory effect and the thermodynamics of an ensemble of spinning objects gives rise to a hysteresis effect, which can be termed Gravo-Thermo memory. This effect can be studied either through a statistical approach or via kinetic theory. Here, we present a general kinetic theory model for the general case of a fluid composed of spinning extended objects in the presence of gravity.

We develop a phase-space description of classical scattering in which the matter sector of the Dyson S-matrix is partially Weyl transformed while the radiation sector remains operator valued. The resulting S-matrix symbol provides a common origin for several classical observables: we show that the inclusive waveform, the classical displacement in phase-space (i.e. the impulse and position shift), and the angular momentum arise as different projections of the same object. We show that the partially Weyl-transformed $S$-matrix admits an exponential organisation in terms of an elastic phase and connected radiation kernels, while its inclusive one-point projection admits a coherent representative with waveshape $α_I$ describing classical radiation, extending our recent proposal. Furthermore, we show explicitly how nonlinear gravitational memory can be derived from an inclusive coherent waveshape. The dependence of the waveshape on the hard scattering data naturally leads to a quantum geometry, including an induced Berry connection on the space of waveforms, whose contribution to the phase-space displacement captures both radiation-reaction and static-field effects. We illustrate this structure by deriving static contributions to the position shift and field angular momentum in both scalar QED and gravity.

The observed diversity of galaxy centers motivates the possibility that the local dark matter composition may vary among galaxies. In conventional multicomponent dark matter scenarios, however, large stochastic variations in the relative abundances are not generically expected, with the cold component typically remaining dominant. We perform $N$-body simulations with a subdominant ultralight dark matter component carrying significant large-amplitude small-scale isocurvature perturbations. We find that although nonlinear evolution largely homogenizes its fraction on galactic scales,ultralight dark matter can still be enhanced and even dominate the centers of small halos because large initial ultralight dark matter fluctuations seed early potential wells that later form halo centers. The ultralight-dominated region can extend beyond $0.01R_{\rm vir}$ and account for more than half of the central dark matter density, even for a cosmological ultralight dark matter fraction below $O(10\%)$. This central segregation provides a possible route to stochastic cusp--core diversity, potentially explaining the observed diversity of galaxy centers.

We construct a new family of static, electrically charged, cylindrically symmetric black-string solutions of four-dimensional Einstein--Yang--Mills theory with a negative cosmological constant, supported by a genuinely non-Abelian $SU(2)$ vortex field. The coexistence of electric and vortex sectors renders the standard single-function Lemos metric inconsistent with the Einstein equations, requiring a three-function metric compatible with the anisotropic Yang--Mills stress tensor. Regular near-horizon and asymptotic AdS expansions provide boundary data for numerical integration of the complete field equations. Two limiting sectors are recovered: vanishing electric horizon datum yields the neutral Lemos black string with zero Yang--Mills field strength, while switching off the vortex component gives the embedded $U(1)\subset SU(2)$ charged Lemos--Zanchin solution. Perturbations about the latter show that genuinely non-Abelian hair appears at linear order through the commutator field strength, whereas its backreaction on the electric profile and geometry begins at quadratic order. The horizon equations yield the analytic local non-degeneracy bound $R_1^{\rm crit}=s_0α\sqrt{3/(4πG)}$. The asymptotic geometry exhibits a quadratic correction absorbable into an effective Abelian charge and a cubic coefficient giving the first irreducible asymptotic signature of the non-Abelian hair. The entropy obeys the Bekenstein--Hawking area law, while the temperature difference from the embedded Abelian solution arises through the asymptotic lapse normalization. The fully backreacted numerical solutions are nonlinear realizations of this transverse non-Abelian deformation.

Recently we have demonstrated that black hole radiation can be smoothly extended to the zero-temperature limit. Here we analyse entropy variations at the zero temperature limit and evaluate the validity of the Generalized Second Law (GSL). Typically one verifies that the entropy gain in the exterior region compensates for the entropy loss of the black hole due to evaporation. However an anomalous feature emerges at the zero temperature limit. The fact that the emission is restricted to the modes $ω<mΩ$, renders the variation of the horizon area of a Kerr black hole positive definite. Simultaneously the von Neumann entropy of the exterior region increases both for bosonic and fermionic modes. The dual entropy gain at the zero temperature limit marks a robust conservation of the GSL. We demonstrate that the dual increase also applies to Kerr-Taub-NUT black holes whose entropy is neither directly proportional to the horizon area nor analytically integrable.

We present a spacetime that describes a rotating and charged black hole immersed in an external magnetic field. This exact solution to the Einstein-Maxwell equations has a surprisingly simple form which reduces to standard Kerr-Newman metric, and to the uniform Bertotti-Robinson magnetic universe. We show that the Kerr-BR solution presented in [Phys. Rev. Lett. {\bf 135}, 181401 (2025)] has a special charge, and we identify a genuine Kerr black hole without any charge, in the magnetic field. In the weak-field limit it gives the Wald solution. We analyze main physical properties of the new family, namely singularities, horizons, regularity of axes, charges, entropy and temperature.

We present a systematic derivation of regular black hole solutions—and their horizonless counterparts—that achieve regularization via an anti─de Sitter core. These geometries emerge as polymerized vacuum solutions inspired by loop quantum gravity, constituting effective quantum gravity configurations that admit a Birkhoff-type theorem and are uniquely determined by their mass. Using an auxiliary relational dust clock, together with the absence of gravitational waves in spherical symmetry, we exploit the structural ultralocality of the system to decompose the dynamics into independent shell degrees of freedom. The dust field acts as a reference clock for deparametrization and does not source the vacuum geometries considered here. These assumptions tightly constrain the Lemaître-Tolman-Bondi shell Hamiltonian to a factorized form and the static vacuum metric function to a universal expression. We examine the possibility of a bounce and analyze how its presence is encoded, or missed, in finite-order effective truncations of the full model. The procedure for deriving the explicit physical Hamiltonian is described for a generic case before specializing to a specific model of interest. Finally, we construct a four-dimensional covariant completion of the spatially covariant Lagrangian, showing that it belongs to the class of generalized extended mimetic gravity models.