高能暂现源 · 每日文献综述

A comprehensive investigation of nonradial oscillations in neutron star (NS) admixed with gravitationally bounded dark matter (DM) is carried out within the framework of full general relativity. The relativistic mean field (RMF) formalism is employed to illustrate the hadronic equation of state (EOS), while a physically motivated, gravitationally captured, non-uniform fermionic Higgs-portal DM component is incorporated to model DM-admixed NS. The DM distribution is characterized by two free parameters: αM<SUB>χ</SUB>, an effective control parameter that combines the DM concentration and the DM candidate mass, and β, a steepness parameter controlling the DM density distribution. The quasi normal mode (QNM) characteristics such as fundamental (f) mode frequency and its corresponding gravitational-wave (GW) damping time (τ) is calculated for DM-admixed NS by solving the general relativistic perturbed equations involving axial as well as polar modes. The study demonstrates how the inclusion of DM distribution modifies the f-mode frequency and enhances the damping rate, reflecting a stronger coupling between matter and spacetime perturbations. Considering DM effects, the correlation analysis among DM model parameters, NS observables and QNM characteristics also carried out. Analytic fits for the <mml:math><mml:mrow><mml:mi>f</mml:mi><mml:mo>-</mml:mo><mml:mi>C</mml:mi><mml:mo>-</mml:mo><mml:mi>τ</mml:mi></mml:mrow></mml:math> and <mml:math><mml:mrow><mml:mi>f</mml:mi><mml:mo>-</mml:mo><mml:mstyle><mml:mi>Λ</mml:mi></mml:mstyle><mml:mo>-</mml:mo><mml:mi>τ</mml:mi></mml:mrow></mml:math> relations are constructed and calibrated for DM-admixed NS models. Building upon asteroseismic universal relations (URs), multimessenger constraint from the GW170817 event is employed by mapping the tidal deformability Λ<SUB>1.4</SUB> into the (f<SUB>1.4</SUB>, τ<SUB>1.4</SUB>) space, thereby providing observational bounds on the oscillation properties of canonical DM-admixed NS model.

We present new observations of the metal-poor ($< 0.1$ $\rm Z_\odot$) Type II supernova 2023ufx and its host galaxy. The deep nebular spectrum, obtained roughly a year after explosion, has a triple-peaked [O I] emission profile suggesting an asymmetric explosion. Comparison to nebular spectra models suggests a zero-age main sequence mass of $ M_{\rm ZAMS} \sim 25-35$ $\rm M_\odot$, which is supported by the low [Ca II]/[O I] emission-line ratio of $\approx0.4$. The diminishing, broad, boxy H$α$ emission and flattening of the light curve in the late ($\sim2$ yr) photometry suggest a complex mass-loss history in the centuries to millennia before explosion. New optical and near-infrared imaging of the host galaxy confirms that it is a dwarf, with a stellar mass of $10^{6.6\pm0.1}$ $\rm M_\odot$ and a SFR of $10^{-2.5\pm0.1}$ $\rm M_\odot$/yr. Results from both SED fitting and galaxy stellar mass-metallicity scaling relations all lead to an environmental metallicity estimate of $0.02-0.07$ $\rm Z_\odot$. Taken together, these observations confirm that SN 2023ufx is the explosion of a very metal-poor, heavily stripped red supergiant.

We test whether constraints on the nonlinear interaction $ξ$IDE are stable under different treatments of the Type Ia supernovae absolute calibration. \textit{Fermi} GRBs measurements and the Amati-relation parameters are fitted jointly with PantheonPlus SNe Ia, DESI DR2 BAO, and an updated cosmic-chronometer compilation. We compare the PantheonPlus-SH0ES route, which retains the SN absolute calibration, with the PantheonPlus-only route, in which the SN absolute magnitude is analytically marginalized. The GOLD GRB sample is adopted for the main analysis, while the FULL GRB sample is used to assess sample dependence. For the interaction parameter $γ\equivξ+3w$, where $γ=0$ denotes the non-interacting limit, the GOLD sample gives $γ=1.453^{+1.297}_{-1.597}$ for the PantheonPlus-SH0ES and $γ=-0.634^{+1.668}_{-2.486}$ for the PantheonPlus-only. Although the posterior medians correspond to opposite directions of energy transfer, neither route excludes $γ=0$ at 68\% credibility, and the reconstructed interaction rate remains consistent with zero over the redshift range considered. Replacing the GOLD sample with the FULL sample produces negligible changes in the interaction constraints. Moreover, $w$CDM and CPL achieve likelihood improvements comparable to that of $ξ$IDE, while the information criteria do not consistently favor the interacting model. A redshift-bin diagnostic finds no significant redshift evolution of the Amati relation. We find no compelling evidence for a dark sector interaction that is robust to the choice of SN calibration or specifically favored over noninteracting dark energy extensions.

Spinning, deformed compact objects such as neutron stars are canonical sources of continuous gravitational waves. These objects may be born with magnetic fields that can strongly influence their spin evolution and, consequently, their gravitational wave detectability. Employing a Bayesian framework, we use for the first time, the non detection of continuous gravitational waves in the LIGO Virgo KAGRA (LVK) third observing run (O3), using reported amplitude upper limits from various LVK and Einstein@Home searches, to place population level constraints on the birth magnetic field distribution of Galactic compact objects. To this end, we simulate compact object populations whose spin evolution is governed by gravitational wave emission and magnetic dipole radiation. We explore multiple ellipticity models and magnetic field decay timescales, and find that the lower limit on the birth magnetic field distribution hyperparameter $B_0$ is constrained to lie in the range $10^{9.6}\mathrm{G} \lesssim B_0\,\lesssim 10^{13.3}\mathrm{G}$. Furthermore, we reinterpret the number constraints on the total population of Galactic compact objects, reported previously by \citet{Prabhu_2024}, as upper limits on the number of compact objects with a population averaged magnetic field, presented as a function of ellipticity and gravitational wave frequency for all searches considered here.

The field of gravitational wave "dark siren" cosmology is facing a number of challenges surrounding the way in which galaxy catalogue data is incorporated into the analysis. The three biggest challenges are adequately compensating for galaxy catalogue incompleteness, robust treatment of galaxy redshift and source properties, and the as-yet unknown host galaxy weighting model. We present an updated methodology for inferring cosmological parameters using dark sirens and incomplete galaxy catalogues. By switching to a sampled redshift prior, rather than one which is pre-computed on a grid, we can jointly infer parameters which describe the population of gravitational-wave hosting galaxies, alongside the gravitational wave population and cosmological model. Using the cosmological inference software gwcosmo, we reproduce a subset of GWTC-5.0 cosmology results, then extend the analysis to jointly infer the host galaxy weighting model - the first measurement of its kind to do so - leading to an updated measurement of the Hubble constant with $H_0 = {71.9}_{-7.5}^{+9.1}$ km s$^{-1}$ Mpc$^{-1}$ (median and 68% symmetric credible interval). This innovative new method opens the door to solving several of the biggest challenges currently facing the field of dark siren cosmology.

GWTC-5 has revealed a subpopulation of merging binary black holes (BBHs) with a high-spin primary black hole (BH) and possibly unequal BH masses. GW241110 additionally exhibits a large spin-orbit misalignment, which suggests a hierarchical-merger origin. However, other formation scenarios are possible or even likely, especially for events without constraints on spin-orbit misalignment. As an alternative to hierarchical mergers, we investigate whether binary evolution can produce unequal-mass BBH mergers with a high-spin primary BH. Rather than performing comprehensive population-synthesis calculations, we examine the evolutionary pathways of forming merging BBHs and assess their uncertainties. We identify two possible pathways for producing unequal-mass BBHs with a high-spin primary. In initially wide binaries, mass-ratio reversal can make the tidally spun-up second-born BH both more massive and more rapidly rotating than the first-born BH; alternatively, in an initially close, unequal-mass binary, the primary star may evolve chemically homogeneously, while the secondary star evolves normally, producing a high-spin first-born BH that is more massive than its companion. Generally, large spin-orbit misalignment can be produced by large natal kicks or tertiary-induced nodal precession and/or Zeipel-Lidov-Kozai oscillations. We conclude that hierarchical mergers are not uniquely required to produce unequal-mass BBHs with a high-spin primary BH, although each isolated-binary pathway faces important theoretical constraints. Future detections of more merger events with primary BH spins around 0.7 would discriminate between binary evolution and hierarchical merger origin.

We present the Active Galactic Nuclei Database (AGN-DB), a comprehensive, multi-wavelength catalog compiled from more than 100 publicly available AGN catalogs and samples released by the end of 2025, spanning radio to $γ$-ray wavelengths. The database contains approximately 8.1 million unique sources, approximately 7.8 million of which remain after flagging stellar contaminants, and approximately 6.8 million of these are classified as AGN. Source cross-matching across catalogs is performed using Lyra, a Bayesian likelihood-ratio framework that jointly considers positional uncertainties, source densities, and photometric information to compute posterior match probabilities. The resulting catalog provides astrometric coordinates, redshifts, photometry, and classifications for each unique source. All multi-catalog provenance is preserved. For every property, we store the full array of values and originating catalog identifiers, enabling multi-epoch and multi-survey analyses. In this paper, we describe the AGN-DB pipeline, including the cross-matching methodology, and present the statistical properties of the v1.0 catalog. AGN-DB is designed to enable population studies, spectral energy distribution modeling, AGN classification, and variability analyses at an unprecedented scale. Its pipeline is designed to facilitate the integration of new catalogs, allowing AGN-DB to be updated regularly, with releases planned at least annually.

Current neutron star equation-of-state inferences assume that a common equation of state describes all neutron stars. However, {poorly understood dense-matter physics may give rise to distinct long-lived stellar subpopulations following different mass--tidal-deformability relations, invalidating this assumption. In this Letter, we demonstrate that next-generation gravitational-wave observatories enable neutron star equation-of-state universality to be transformed from an assumption into a testable hypothesis. By combining hierarchical Bayesian inference with a piecewise-polytropic parametrization of the neutron star equation of state, we establish a framework for testing equation-of-state universality with next-generation gravitational-wave observatories. We find that about 30 (50) loud binary neutron star mergers with network SNRs above 100 are sufficient to provide compelling evidence for departures from equation-of-state universality, even if only 20% (10%) of the population exhibits one of the representative non-universality parametrizations considered here.

Third-generation (3G) gravitational-wave detectors will observe binary-neutron-star inspirals for nearly a day, so Earth's rotation becomes part of the signal rather than a negligible correction. This destroys the usual separation between intrinsic and extrinsic parameters and creates a major computational bottleneck for Bayesian inference. We show that the exact five-harmonic Jaranowski-Krolak-Schutz (JKS) decomposition restores the separation of the rotating antenna amplitude response from the computationally expensive intrinsic waveform calculations. By sampling the intrinsic waveform on a frequency grid set by its phase curvature and then applying error-controlled relative binning, likelihood evaluations for a 21.3-h signal are accelerated by O(10^4), making day-long 3G signal inference practical.

In this work, we perform a relativistic test of the spacetime geometry of Sagittarius A* (Sgr A*) using the orbit of the S2 star. We consider a broad class of compact object models, including Schwarzschild, Reissner-Nordström, Bardeen, Hayward, and Simpson-Visser black holes, as well as the Janis-Newman-Winicour naked singularity spacetime. For each geometry, we integrate the timelike geodesic equations and consistently project the resulting trajectories onto astrometric and spectroscopic observables, incorporating Rømer time delay and relativistic redshift effects. The theoretical predictions are tested with current Very Large Telescope (VLT) observations of the S2 star, while simultaneously imposing constraints from the Event Horizon Telescope shadow size. We find that several spacetimes that are degenerate at the level of shadow imaging, most notably Schwarzschild, Reissner-Nordström, and Bardeen regular black hole geometries, remain statistically indistinguishable when tested against present S2 data. We further carry out a statistical model comparison based on the Akaike and Bayesian information criteria (AIC and BIC) to evaluate the relative performance of the alternative spacetime models. Our analysis also constrains the generalized charge like parameter q/M in non-Schwarzschild spacetimes based on current S2 star observations, and identifies specific black hole and horizonless geometries that can be further tested with forthcoming high precision astrometric observations from the VLT and Keck telescopes.

We examine the geodesic structure, shadow, quasi-periodic oscillations (QPOs), thermodynamic properties, and greybody factors (GBFs) of a static, spherically symmetric black hole (BH) embedded in a beta dark matter halo (DMH). The photon sphere, shadow radius, and photon trajectories grow with increasing DMH density, producing deviations that can be tested against Event Horizon Telescope (EHT) bounds for Sgr A* and M87*. For massive particles, we calculate the innermost stable circular orbit (ISCO), the radiative efficiency, and the epicyclic frequencies, and we read off the epicyclic resonance (ER) model predictions for twin-peak QPOs. With the emcee Markov chain Monte Carlo (MCMC) sampler, these predictions are compared with observed QPO data from three stellar-mass X-ray binaries (XTE J1550--564, GRO J1655--40, GRS 1915+105), the supermassive BH Sgr A*, and the intermediate-mass candidate M82 X-1, yielding 1σ constraints on the BH mass and the DMH parameter κ for all five sources. The thermodynamic analysis gives a single phase transition whose critical horizon shifts as the halo parameters vary, while the spin-0 GBFs show that the DMH lowers the potential barrier and lets more low-frequency scalar emission through. The beta DMH thus leaves measurable signatures in X-ray timing, shadow imaging, accretion efficiency, and BH ringdown spectra.

The neutron lifetime τ<SUB>n</SUB> is a fundamental input to Big Bang Nucleosynthesis (BBN) that controls the neutron-to-proton ratio at the onset of element production and thus the primordial helium mass fraction Y<SUB>P</SUB>. A persistent ≃ 4σ tension exists between beam-based experiments (<mml:math><mml:mrow><mml:msubsup><mml:mi>τ</mml:mi><mml:mi>n</mml:mi><mml:mrow><mml:mrow><mml:mi>b</mml:mi></mml:mrow><mml:mi>e</mml:mi><mml:mi>a</mml:mi><mml:mi>m</mml:mi></mml:mrow></mml:msubsup><mml:mo>≈</mml:mo><mml:mn>888.0</mml:mn><mml:mo>±</mml:mo><mml:mn>2.0</mml:mn></mml:mrow></mml:math> s) and cryogenic bottle/trap experiments (<mml:math><mml:mrow><mml:msubsup><mml:mi>τ</mml:mi><mml:mi>n</mml:mi><mml:mrow><mml:mrow><mml:mi>b</mml:mi></mml:mrow><mml:mi>o</mml:mi><mml:mi>t</mml:mi><mml:mi>t</mml:mi><mml:mi>l</mml:mi><mml:mi>e</mml:mi></mml:mrow></mml:msubsup><mml:mo>≈</mml:mo><mml:mn>879.4</mml:mn><mml:mo>±</mml:mo><mml:mn>0.6</mml:mn></mml:mrow></mml:math> s). The discrepancy ∆τ<SUB>n</SUB> ≈ 8.6 s translates into a predicted shift in the primordial helium mass fraction of ∆Y<SUB>P</SUB> ≈ 0.0018, or roughly 0.7% of the Standard-Model value. We critically assess whether next-generation astrophysical observations of Y<SUB>P</SUB>, achievable with integral-field-unit (IFU) spectroscopy of metal-poor Blue Compact Dwarf (BCD) galaxies combined with precision spectrophotometric calibration, can resolve this tension. Using a Fisher-matrix forecast over the parameter space {τ<SUB>n</SUB>, Ω<SUB>b</SUB>h<SUP>2</SUP>, N<SUB>eff</SUB>}, we show that a 0.1% determination of Y<SUB>P</SUB>, when combined with a sub-percent measurement of (D/H)<SUB>P</SUB> and Planck-quality CMB data, yields an astrophysical constraint on τ<SUB>n</SUB> whose precision depends critically on the treatment of the effective number of neutrino species N<SUB>eff</SUB>. If N<SUB>eff</SUB> is fixed to its Standard Model value 3.044 --- motivated by the absence of new light species --- a 0.1% determination of Y<SUB>P</SUB> combined with current D/H data already reaches σ(τ<SUB>n</SUB>) ≃ 1.3 s, providing &gt; 6σ discrimination. If N<SUB>eff</SUB> is treated as a free parameter, Planck-quality CMB data are insufficient to break the N<SUB>eff</SUB>--τ<SUB>n</SUB> degeneracy in Y<SUB>P</SUB>, and a next-generation CMB experiment (CMB-S4) with σ(N<SUB>eff</SUB>) ≃ 0.03 is required, yielding σ(τ<SUB>n</SUB>) ≃ 4.3 s at the ~ 2σ threshold. In all cases an independent measurement of the baryon density --- from either primordial D/H or the CMB --- is an essential prerequisite, since τ<SUB>n</SUB> and Ω<SUB>b</SUB>h<SUP>2</SUP> are completely degenerate in Y<SUB>P</SUB> alone.

We study the dynamics of spinning particles around a regular black hole with asymptotically Minkowski cores. The trajectories of spinning particles are described using the Tulczyjew spin-supplementary condition together with Mathisson-Papapetrou-Dixon equations. Our results show that both the black hole parameter k and particle spin s significantly affect the structure of the effective potential, thereby determining the existence and stability of circular orbits. A positive spin increases the effective potential peak, allowing stable orbits closer to the black hole, whereas a negative spin has the opposite effect. The critical spin decreases approximately linearly with k. Furthermore, we study the properties of the innermost stable circular orbit (ISCO), showing that larger values of s or k lead to smaller ISCO radii. The ISCO angular momentum additionally displays a non-monotonic variation with spin. These results reveal the distinctive interplay between spin and the asymptotically Minkowski core geometry and may have important implications for accretion disk physics and gravitational wave observations.

High-frequency gravitational waves (GWs), spanning frequencies from the microwave to the optical band, remain experimentally unexplored despite strong motivation from early-Universe dynamics, high-energy cosmology, and exotic compact objects. We propose a detection framework in which an incident GW excites an eigenmode of a high-Q resonator in the presence of a static magnetic field through GW-induced electromagnetic mode conversion; the resulting cavity field is then read out using atomic sensors placed outside the magnetized volume. We analyze two concrete architectures: microwave detection based on Rydberg transitions and optical/near-infrared Raman schemes. For each, we derive projected strain sensitivities achievable with realistic, though ambitious, magnetic fields, cavity parameters, and atomic ensembles. Under optimistic assumptions on cavity performance, signal coherence, and technical noise, optical Raman implementations could approach benchmark narrowband coherent strain sensitivities relevant for speculative high frequency GW scenarios, while microwave systems may probe benchmark sensitivities in an otherwise unexplored frequency range. These setups motivate advances in high-Q cavities, strong-field magnets, and quantum-limited atomic sensors, with broader implications for quantum instrumentation and fundamental physics.

We use the latest ANTARES Galactic Ridge neutrino measurements to investigate their implications for indirect dark matter (DM) searches. We consider both annihilating and decaying DM scenarios, spanning a wide range of masses and final states, and systematically compare the resulting neutrino fluxes with the expected astrophysical Galactic diffuse emission. Furthermore, we compare the results for different DM density profiles allowed by the observations, from spike and cuspy to cored profiles. We do so for the WIMP model-independent scenario and explore two more specific models: branons and very heavy sterile neutrinos, where a cold DM candidate arises naturally from the theory. We show the potential neutrino measurements in the Galactic Ridge for DM and make predictions for future neutrino observatories.

To date, frequency-dependent squeezed light has been used to reduce quantum noise in interferometric gravitational wave detectors by 6.1 dB (a factor of two). Future upgrades and detectors aim to both reduce quantum noise by 10 dB (a factor of three) and to increase the circulating power in the interferometer arm cavities. Achieving these goals will be extremely challenging due, in part, to the degradations to the squeezed state caused by mode mismatch between the internal interferometer optical cavities and between the auxiliary external cavities. It is therefore imperative to gain a detailed understanding of all sources of mismatch and to obtain experience in mitigating their effects in the current detectors in order to improve astrophysical sensitivity now and in the future. Two types of internal mismatch are identified which are due to the thermal aberrations generated when the test mass optics absorb a small fraction of the circulating arm power. It is found that the dynamics responsible for the degradations caused by the mismatch between the quadratic part of the wavefront of two modes has a characteristic low-pass frequency dependence while the dynamics of the mismatch due to all higher-order thermal aberrations has a high-pass behavior. As a consequence, the two types of mismatch are predominantly responsible for different squeezing degradations; some of which are significant for the current detectors and some of which will only be important for future detectors with longer arms. The behavior of these two types of internal mismatch are described, and the implications for detector design, operation, and characterization are discussed.

We present a Geant4 Monte Carlo simulation of cosmic-ray (CR) hadronic interactions in a spherical molecular cloud (<inline-formula><mml:math><mml:mo>~</mml:mo><mml:mn>5400</mml:mn><mml:msub><mml:mi>M</mml:mi><mml:mo>⊙</mml:mo></mml:msub></mml:math></inline-formula>, 13 concentric shells, <inline-formula><mml:math><mml:msup><mml:mi>r</mml:mi><mml:mrow><mml:mo>-</mml:mo><mml:mn>1.2</mml:mn></mml:mrow></mml:msup></mml:math></inline-formula> density profile) using six primary CR species, protons, alpha particles, carbon, oxygen, silicon, and iron, drawn from GALPROP-HELMOD local interstellar spectra over <inline-formula><mml:math><mml:mrow><mml:mn>1</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>GeV</mml:mi><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>nuc</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula> to <inline-formula><mml:math><mml:mrow><mml:mn>1</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>PeV</mml:mi><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>nuc</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula>, the hadronic interaction regime in which pion production and nuclear spallation dominate the secondary particle output. We compute, for the first time within this framework, radial energy deposition profiles, per-layer secondary production rates, and the differential physical flux of all emerging stable secondaries for the full nuclear CR composition. Energy deposition scales as <inline-formula><mml:math><mml:msup><mml:mi>Z</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:math></inline-formula>, with the secondary cascade dominating <inline-formula><mml:math><mml:mo>&gt;=</mml:mo><mml:mn>92</mml:mn><mml:mo>%</mml:mo></mml:math></inline-formula> of the deposited energy in the dense core for all species. Alpha particles produce the highest integrated gamma-ray flux (<inline-formula><mml:math><mml:mrow><mml:mn>0.125</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>cm</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>sr</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula> above 100 MeV), followed by protons (<inline-formula><mml:math><mml:mrow><mml:mn>6.71</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>cm</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mi>sr</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></inline-formula>); together, they account for <inline-formula><mml:math><mml:mo>≈</mml:mo><mml:mn>96</mml:mn><mml:mo>%</mml:mo></mml:math></inline-formula> of the total emerging gamma-ray and neutrino fluxes. A robust composition-diagnostic signature emerges in the neutrino sector: the <inline-formula><mml:math><mml:msub><mml:mi>ν</mml:mi><mml:mi>e</mml:mi></mml:msub><mml:mo>/</mml:mo><mml:msub><mml:mover><mml:mi>ν</mml:mi><mml:mo>̄</mml:mo></mml:mover><mml:mi>e</mml:mi></mml:msub></mml:math></inline-formula> ratio above 100 MeV decreases from <inline-formula><mml:math><mml:mo>≈</mml:mo><mml:mn>6.4</mml:mn></mml:math></inline-formula> for protons, driven by the <inline-formula><mml:math><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:mo>/</mml:mo><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msup><mml:mo>≈</mml:mo><mml:mn>8</mml:mn><mml:mi>--</mml:mi><mml:mn>11</mml:mn></mml:mrow></mml:math></inline-formula> charge asymmetry, to <inline-formula><mml:math><mml:mo>≈</mml:mo><mml:mn>2.8</mml:mn></mml:math></inline-formula> for <inline-formula><mml:math><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mi>Z</mml:mi></mml:math></inline-formula> nuclei (C, O, Si), directly encoding the isospin content of the primary CR beam in an observable flux ratio. Secondary nuclear clusters (<inline-formula><mml:math><mml:mi>d</mml:mi></mml:math></inline-formula>, <inline-formula><mml:math><mml:mi>t</mml:mi></mml:math></inline-formula>, <inline-formula><mml:math><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>He</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math></inline-formula>, <inline-formula><mml:math><mml:mrow><mml:mi>α</mml:mi></mml:mrow></mml:math></inline-formula>, and heavier ions up to <inline-formula><mml:math><mml:mi>Z</mml:mi><mml:mo>=</mml:mo><mml:mn>26</mml:mn></mml:math></inline-formula>) emerge exclusively for nuclei heavier than protons, contributing at the <inline-formula><mml:math><mml:mo>≈</mml:mo><mml:mn>32</mml:mn><mml:mo>%</mml:mo></mml:math></inline-formula> level of the secondary proton flux for light clusters, while heavy-ion fragments remain 1 to 2 orders of magnitude below the secondary proton channel.

We analyze scalar, vector, and axial tensor perturbations in a Schwarzschild-type static spherically symmetric solution of modified <inline-formula><mml:math><mml:mi>f</mml:mi><mml:mo>(</mml:mo><mml:mi>R</mml:mi><mml:mo>)</mml:mo></mml:math></inline-formula> gravity. This solution differs from the Schwarzschild metric of general relativity through the presence of a linearly growing term and a logarithmic correction, and it depends on four integration constants. Using the higher-order Wentzel-Kramers-Brillouin approximation and an analytical method, we calculate the quasinormal modes (QNMs) for all three types of perturbations. Our results show that, for appropriately chosen parameter values, the QNMs closely match those of the Schwarzschild black hole. In particular, the model parameter <inline-formula><mml:math><mml:mi>A</mml:mi></mml:math></inline-formula> produces a nonlinear increase in both the oscillation frequency and damping rate of ringdown gravitational waves. A similar effect arises for the parameter <inline-formula><mml:math><mml:mi>η</mml:mi></mml:math></inline-formula> when <inline-formula><mml:math><mml:mi>A</mml:mi></mml:math></inline-formula> is small, while for larger <inline-formula><mml:math><mml:mi>A</mml:mi></mml:math></inline-formula> values the effects are opposite, where the scalar perturbations display a distinct deviation compared to the vector and axial tensor cases. Contour plots of QNMs in the parameter space support these findings. Finally, time-domain profiles are obtained to illustrate the dynamical evolution of the gravitational wave signal.

We propose using supernova microlensing to search for ultracompact minihalos and other extended dark structures seeded by enhanced primordial small-scale power. Unlike conventional microlensing searches, which are often optimized for primordial black holes, cosmological supernovae are sensitive to lenses with physical sizes comparable to their Einstein radii (up to $\sim {\rm pc}\left(M/10^4M_\odot\right)^{1/2}$ scale), opening a qualitatively different region of dark object parameter space. We compute the extended object detection efficiency relative to point lenses. We then show how projected limits on the abundance of ultracompact minihalos can be mapped, in benchmark formation scenarios, onto constraints on the primordial power spectrum. With the Vera C. Rubin Observatory expected to deliver an unprecedented LSST supernova sample, supernova microlensing is poised to become a timely and complementary probe of small-scale structure and the physics of the early Universe.

We update the X-ray information given in Maselli et al. (2024) for five bright radio sources in the SMS4 catalog, thanks to additional observations with the X-Ray Telescope (XRT) on board the Neil Gehrels Swift Observatory (hereafter Swift) carried out through February 2026. X-ray emission from MRC B1754-597, previously based only on data from the eROSITA-DE DR1 catalogs, is now detected also by Swift, which yields a more precise positional uncertainty. Thanks to ~7 ks of additional exposure with Swift we are now able to detect MRC B1817-391, a source for which no X-ray counterpart is found in eROSITA-DE DR1. Another source that is not detected in the eROSITA-DE DR1 catalogs, and that was not observed by Swift earlier than 2025, is MRC B1827-360: with a ~6 ks X-ray observation, the source is detected. Finally, based on ~8 ks of additional exposure, we detect X-ray emission for MRC B2032-350, a source that lies out of the DR1 footprint. In contrast, additional exposure (~2 ks) just gives an upper limit on the X-ray emission of MRC B1814-519. The analysis of the extent and the hardness ratio of the four detected X-ray sources suggests the presence of soft, diffuse X-ray emission as expected from galaxy group cores or hot galaxy coronae. Using the positional uncertainty of the X-ray detections to constrain the search for counterparts at lower energies, we provide a new infrared/optical counterpart for MRC B1817-391 and confirm the counterparts previously reported in the literature for the three remaining sources.

Narrow-line Seyfert 1 (NLSy1) galaxies are key laboratories for studying rapid supermassive black hole (SMBH) growth and active galactic nucleus (AGN) feedback at high accretion rates. We investigate the nearby NLSy1 Ton S180 with VLT-MUSE optical integral field spectroscopy to connect its nuclear accretion properties with the spatially resolved ionized gas and host-galaxy kinematics. We modeled the unresolved nuclear spectrum and applied a custom point spread function subtraction to recover the host-galaxy emission on kiloparsec scales. The nuclear spectrum requires a complex permitted-line decomposition and a blueshifted [O III] outflow component. Single-epoch estimators and the stellar velocity dispersion imply black hole masses in the range $\log(M_{\rm BH}/M_\odot) = 6.5 - 7.7$. Combined with the observed luminosity, this implies a dimensionless mass accretion rate of $\dot{M} / \dot{M}_{\rm Edd} = 4.1 - 980$, confirming the extreme accretion regime. The host galaxy shows a circumnuclear ring, an inner elongated structure consistent with a bar, and rotation-dominated gas and stellar kinematics. Simple inflow models do not significantly better reproduce the observed velocity field. We detect a resolved ionized outflow extending about 2 kpc west of the nucleus, with mildly blueshifted velocities (with a maximum of $v_{\rm max} \sim 340$ km s$^{-1}$). Its mass outflow rate is only $\sim 4.2 \times 10^{-4}\,M_\odot\,\mathrm{yr}^{-1}$, whereas the unresolved nuclear outflow reaches $v_{\rm max} \sim 1140$ km s$^{-1}$ and $\dot{M}_{\rm out} > 1.5\,M_\odot\,\mathrm{yr}^{-1}$. This contrast may reflect either weak ionized coupling from nuclear to galactic scales or different episodes of AGN activity over time. These results show that Ton S180 is undergoing rapid SMBH growth, while the observed ionized outflow remains confined to the inner few kiloparsecs and is weak on host-galaxy scales.

We present a phenomenological frequency-domain model for the gravitational-wave (GW) memory signal from nonspinning binary-black-hole mergers on quasicircular orbits. We develop separate amplitude and phase models for the dominant $(l,m)=(2,0)$ spherical-harmonic mode of the GW memory signal. The amplitude and phase models are built from superpositions of elementary and transcendental functions, which can be evaluated efficiently. Both portions of the model are calibrated against a numerical-relativity surrogate model over mass ratios from one to eight. Their accuracy is assessed by computing their mismatch with the numerical-relativity models using the Advanced LIGO sensitivity curve from the fourth observing run. The mismatches are of the order $10^{-4}\unicode{x2013}10^{-3}$ over the parameter space of total mass covered by LIGO. The resulting frequency-domain model is a more computationally efficient waveform model for the GW memory signal than a related time-domain model earlier produced by the authors. An open-access implementation of both the time-domain and frequency-domain models is provided in the Python package GWMemoryModel, which can be used for relevant analyses of nonspinning binary black holes.

Quadratic $f(R)$ gravity carries a massive scalar degree of freedom, the scalaron, whose finite range $λ$ screens its influence on the geometry outside a compact object. We show that this screening severs the exterior of a black hole from that of a neutron star of the same mass. The correction to the Schwarzschild metric is Yukawa-suppressed, falling as $e^{-r/λ}$ instead of polynomially in the coupling, and is thus invisible to any expansion in powers of that coupling; also, the exterior is intrinsically isotropic, so that inverting the temporal potential alone, as in single-potential solutions, fails to solve ]field equations. Applying the Gauss-Bonnet theorem to this geometry, we find the leading deflection angle to be exactly the general-relativistic $4GM/b$, the scalaron contributions cancelling identically in the combination that bends light. The first correction carries the unfamiliar signature $λ^{-1/2}b^{-3/2}e^{-b/λ}$, screened beyond the scalaron range and confirmed against direct quadrature to around 20% at $b=4λ$, improving to 7% at $b=12λ$. What survives is not a difference of degree but of kind. The three ingredients that deliver it, non-analyticity in the coupling, the intrinsically isotropic gauge and the pressure-weighted scalar charge, are here obtained within a single, self-consistent derivation for the first time. A static black hole carries no scalar hair, and lenses precisely as GR requires; a neutron star acquires a scalar charge weighted by the pressure supporting it against collapse, and does not. Weak lensing hence closes as a discriminant of the theory, whilst the horizon, as against a material surface, remains one in principle. The observational advantage lies not in bending angles at large $b$ but in the strong-field imaging of the photon sphere, and in the stellar interior, where the scalar charge is fixed by EoS.

Within the entropic gravity paradigm introduced by Verlinde, one assumes that the microscopic degrees of freedom residing on the holographic screen obey the equipartition law of energy. Nevertheless, implications of statistical mechanics suggest that this energy sharing can acquire corrections that depend on temperature. Taking such modifications into account leads to altered gravitational field equations when derived from thermodynamic considerations. We solve the resulting modified Einstein equations in the case of a static, spherically symmetric spacetime and determine the general structure of the metric components. Our findings indicate that if the temperature correction function behaves as $f(T)\propto T^{2}$, the corresponding spacetime geometry reduces to the flat Minkowski metric. Therefore, to obtain small deviations from flatness, it is necessary to consider slight departures from this purely quadratic temperature dependence. Such deviations can be interpreted as encoding additional gravitational effects, potentially associated with matter contributions that are not entirely described by the holographic screen. As a result of these effects, the effective gravitational potential acquires a logarithmic correction, which can give rise to deviations from Newtonian gravity. This aspect is especially significant in the regime of very weak gravitational fields, where these corrections may affect particle motion and could carry implications for both astrophysical and cosmological contexts.

The bright blazar OJ~287 has demonstrated a sequence of flares, which are well explained by a quasi-Keplerian orbit model. The flares are associated with the impact of the secondary on the accretion disk of the primary. The orbit must precess in order to produce the correct sequence of flares, and from the precession rate we calculate the mass of the primary. This precession rate gives the mass of the primary $M_{BH} = (18.35\pm0.05) \times 10^9 M_{\odot}$. Two kinds of flares have been identified: direct flares from the impacts, and tidal flares arising from an increased accretion flow into the jet. The precession rate and the primary black hole mass may be independently determined from both sets of flares; the tidal flare of October 2022 was recommended for an intense campaign for this reason. This paper describes these observations over a wide spectral range. We show that the October 2022 flare fits the expectations for a tidal flare and thus supports the earlier determination of the mass of the binary black hole system in OJ 287. The mass of the primary may also be deduced from secondary indicators such as the correlation with the hydrogen line strength and the black hole mass. These studies require that the mass is above $M_{BH} \sim 10^{10} M_{\odot}$, but do not specify the value more exactly.

Gravitational-wave~(GW) transients, strongly lensed by intervening galaxies and clusters, are expected to constitute a small fraction ($\sim 0.1$-$0.5\%$) of the events detectable by ground-based detectors. A strongly lensed binary black hole (BBH) merger will produce multiple copies of the GW signal arriving at different times at the detector. The abundance and time-delay distribution of these lensed events are sensitive to the mass, density profile, and redshift distribution of the lens population, and in turn, to the underlying nature of dark matter. Jana et al. (Phys.Rev.Lett. 135 (2025) 11, 111402) recently proposed a method to constrain the masses of warm dark matter (WDM) particles making use of the strongly lensed events detectable by next-generation GW detectors. In this work, we investigate the prospects of constraining the mass of the WDM particle using upcoming observations of the upgraded LIGO-Virgo-KAGRA network. This requires a careful modeling of the detector selection effects. The upcoming fifth observing run (O5) is expected to yield only a modest bound, since only a few lensed pairs are expected at that early stage. By the sixth observing run (O6), we forecast a bound on the WDM particle mass, $m_{\rm wdm}^{-1} \lesssim 0.1$-$0.2\text{keV}^{-1}$ ($m_{\rm wdm} \gtrsim 5$-$10\text{keV}$), which is comparable to the tightest existing astrophysical constraints. Runs beyond O6 will tighten the constraint by roughly an order of magnitude. Strongly lensed GWs therefore offer a complementary, competitive, and independent probe of dark matter.

We present the Hubble diagram and cosmological constraints resulting from the combination of the Pantheon+ and DES-SN5YR supernova (SN) samples, which we refer to as Unite. Unite updates Pantheon+, including methodology improvements that the DES sample enabled, and adds the new SN from the DES survey. This represents the most comprehensive and internally consistent SN Ia dataset available, consisting of 2884 likely type Ia supernovae. This work features consistent SN Ia modelling, sample selection, and bias corrections. We also redetermine host-galaxy stellar masses for over 98% of the sample using a consistent framework. Using Unite alone, for a flat universe with a cosmological constant (Flat-$Λ$CDM), we find $Ω_{\rm m} = 0.310^{+0.012}_{-0.011}$. We further present constraints using the Unite sample combined with Cosmic Microwave Background and both DES and DESI Baryon Acoustic Oscillation data. We find strong evidence of tension between CMB measurements and the combined BAO and supernova datasets when fitting a model with constant dark energy equation of state ($w$), which is alleviated when allowing $w$ to vary with time. For a flat universe with dark energy that has a time-evolving equation of state parametrized by $w_0$ and $w_a$ we find $(Ω_{\rm m},w_0,w_a) = (0.305\pm0.004,-0.861^{+0.044}_{-0.042},-0.60^{+0.17}_{-0.19})$ with a dark energy Figure of Merit of 315. This corresponds to a $\sim30\%$ reduction in the area of the $w_0-w_a$ confidence region relative to previous constraints from the combination of DES Y6, DESI-DR2, and CMB data (arXiv:2605.27221). The Bayesian evidence indicates only weak preference for time evolving dark energy, whereas frequentist analyses yield a preference over Flat-$Λ$CDM at a significance of $2.5σ$ when using the maximum $\mathit{a\ posteriori}$ probability, or $3.1σ$ when using the maximum likelihood.

We present the photometric--microlensing metallicity method, which enables metallicity measurements of M-dwarf lenses out to bulge distances by combining their multi-band photometry with the angular Einstein radius. The cool atmospheres of M dwarfs contain abundant molecules, whose broad absorption bands make their positions in an optical--NIR color--absolute magnitude diagram sensitive to metallicity. The angular Einstein radius provides the mass--distance constraint needed to infer the lens absolute magnitude, while the intrinsic M-dwarf locus and reddening vector are non-parallel in color--color space, allowing the lens extinction and intrinsic color to be inferred simultaneously from its multi-band photometry, thereby recovering the lens intrinsic position in the metallicity-sensitive color--absolute magnitude diagram. The method requires three-band lens photometry spanning roughly the R, Z, and K bands, making it particularly well suited to Roman through its high-resolution F062, F087, and F213 imaging. With the planned Roman Galactic Bulge Time-Domain Survey (GBTDS) observations plus an additional $\sim$8 hr of F062 imaging per field ($\sim$40 hr in total) roughly a decade after Roman launch, host metallicities could be measured for $\sim$150 planetary systems under the GBTDS yield forecast, with a typical $1σ$ precision of $\sim$0.25 dex from our mock-recovery analysis. Applied homogeneously to GBTDS microlensing events with and without detected planets, the method would enable the first measurement of the occurrence--metallicity relation for cold low-mass planets beyond the snow line, constrain the low-metallicity cutoff for their formation, and extend occurrence--metallicity studies into the inner Galaxy.

Current consensus suggests that Type Ia supernova (SN Ia) brightnesses post light-curve standardization correlate with their host-galaxy stellar masses, which must be accounted for to obtain accurate cosmological constraints. Vincenzi et al. (2025) showed that different host-galaxy stellar mass measurements for the same dataset can produce redshift-dependent differences of order $\sim 0.01$ mag. We present internally consistent host-galaxy stellar masses remeasured using aperture photometry and spectral energy distribution (SED) fitting for SN-Unite, which combines the Pantheon+ and the Dark Energy Survey five-year (DES-SN5YR) samples into the largest SN Ia cosmology sample to date, with 2884 likely SNe Ia. We quantify the impact of photometry and SED fitting choices on SN-Unite cosmological parameters in Flat$w$CDM and find shifts well below statistical uncertainties. Our stellar masses differ from the Pantheon+ data release partly due to a redshift-dependent internal inconsistency within Pantheon+, while remaining largely consistent with DES-SN5YR (DES-Dovekie). When the Pantheon+ subsample of SN-Unite is combined with Baryon Acoustic Oscillations (BAO) and Cosmic Microwave Background (CMB) measurements, the significance for time-evolving dark energy increases from 2.6$σ$ to 3.4$σ$ based on the maximum \textit{a posteriori} when our newly derived host-galaxy stellar masses replace the Pantheon+ data-release host-galaxy stellar masses, while DES-Dovekie remains virtually unchanged, consistent with the findings of Hoyt et al. (2026). By remeasuring the host-galaxy stellar masses using a consistent framework throughout the whole sample, we improve the robustness of the SN-Unite cosmological constraints against systematic differences in host-galaxy stellar mass measurements.

Modified gravity theories provide a compelling alternative to dark energy in explaining cosmic acceleration, and nonlinear oscillatory models like f(R)=cosR exhibit rich dynamical behavior capable of producing cyclic universes. In this work, we investigate the cosmological implications of f(R)=cosR gravity within the framework of fractional-action cosmology (FAC), focusing on early-universe dynamics, stability, and astrophysical consequences. We derive the weighted Friedmann equations for a spatially flat FRW universe, identify the conditions for curvature-driven acceleration, and analyze the oscillatory behavior of the Ricci scalar as a driver for expansion and contraction cycles. The fractional action parameter α modulates the amplitude and period of these cycles, influencing both the early-universe and late-time dynamics. We show that stability conditions, such as positivity of the effective gravitational coupling and nonnegative scalaron mass squared, are satisfied for small deviations α≤1, allowing a dynamically stable cyclic universe. We further explore astrophysical consequences, demonstrating that oscillations in curvature can modulate star formation rates, alter galaxy formation and evolution, and influence cluster dynamics, while also producing subtle signatures in the cosmic microwave background and primordial gravitational waves. Our analysis suggests that cyclic f(R) gravity with FAC provides a unified framework for early acceleration, long-term cosmic oscillations, and observable astrophysical effects, offering a testable alternative to standard ΛCDM cosmology.

Building on recent work introducing the idea of Quasilocal Probability in curved spacetime, we develop its observational implications for black hole ringdown in detail. We show that horizon-induced probability flux leads to an effective non-Hermitian dynamics producing three distinctive signatures, which are correlated multi-mode deviations, weak amplitude dependence and a mismatch between waveform damping and energy accounting. These effects arise from a single boundary-flux mechanism and therefore exhibit a constrained, low-dimensional structure not expected in generic modified gravity scenarios. We demonstrate that while individual deviations may be mimicked, their combined pattern provides a robust discriminator of quasilocal probability. We further argue that upcoming gravitational wave observations can probe these signatures at meaningful precision. We also establish that black hole ringdown is a novel arena to test whether quantum mechanical Hermiticity is really a fundamental property or an emergent symmetry in quantum gravity.

In this paper, we explore the implications of the so-called slingshot effect. It represents a rather general phenomenon occurring when a localized source, such as a monopole, quark, or a D-brane, crosses a domain wall separating the confined (Higgsed) and unconfined (Coulomb) phases of the crossing source. The crossover is accompanied by a stretched ``string'' of proper co-dimensionality that confines the source to the domain wall. The effect takes place for different setups, such as phase transitions leading to confinement, both electric and magnetic, as well as in string theoretic inflation with D-branes. We discuss the role of the phenomenon in sourcing gravitational waves and dark matter in the form of Kaluza-Klein gravitons. We also show that the slingshot effect can lead to the formation of primordial black holes in observationally interesting mass ranges for dark matter and high-energy cosmic rays.

This study offers a detailed analysis of domain wall formation and its cosmological consequences in Einstein-Gauss-Bonnet gravity coupled to a scalar field. A central aspect of the model is the scalar field Lagrangian's ability to spontaneously break and restore its Z<SUB>2</SUB> discrete symmetry. This spontaneous symmetry breaking is a fundamental prerequisite for topological defect formation. In this context, domain walls arise as kink-like, solitonic solutions that interpolate between the distinct vacuum states of the theory. We perform a detailed numerical analysis of the dynamics of a neutral scalar field non-minimally coupled to the Gauss-Bonnet invariant, exploring its behavior across different cosmological backgrounds. Our results show that coupling to the Gauss-Bonnet term enables the formation of static domain walls with a fixed proper distance within a de Sitter (inflationary) background. Furthermore, we extend our analysis to a radiation-dominated epoch, where we identify that the cosmic expansion causes the ``melting'' of these domain walls. To assess the potential observational signatures of this scenario, we calculate the predicted spectrum of stochastic gravitational waves generated by the network dynamics using CosmoLattice package. We also examine the possible generation of Primordial Black Holes (PBHs) associated with collapsing domain walls. Regrettably, our calculations indicate that the direct observational detection of such domain walls from this model lies beyond the reach of foreseeable experiments. Our results constitute a No-Go argument against the generation of PBHs as well as of large amplitude GW signals from domain walls in a Scalar-EGB spontaneous symmetry breaking mechanism.

We investigate the shadow and optical appearance of Bardeen black hole (BH) immersed in perfect fluid dark matter (PFDM). Using EHT observations of M87* and Sgr A*, we constrain the DM parameter to a narrow range <mml:math><mml:mrow><mml:mi>b</mml:mi><mml:mo>/</mml:mo><mml:mi>M</mml:mi><mml:mo>~</mml:mo><mml:mi>O</mml:mi><mml:mo>(</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup><mml:mo>-</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo>)</mml:mo></mml:mrow></mml:math> for M87* and to <mml:math><mml:mrow><mml:mi>O</mml:mi><mml:mo>(</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo>-</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msup><mml:mo>)</mml:mo></mml:mrow></mml:math> for Sgr A*. From these constraints we derive a rough prediction for the PFDM density near the shadow scale (R<SUB>sh</SUB> ~ 5M): ρ<SUB>PFDM</SUB> ~ 0.27--2.67 g/cm<SUP>3</SUP> for Sgr A*, dropping to <mml:math><mml:mrow><mml:mo>~</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>24</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>--<mml:math><mml:mrow><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>25</mml:mn></mml:mrow></mml:msup><mml:mspace></mml:mspace><mml:mrow><mml:mi>g</mml:mi><mml:mo>/</mml:mo><mml:msup><mml:mtext>cm</mml:mtext><mml:mn>3</mml:mn></mml:msup></mml:mrow></mml:mrow></mml:math> at 100 pc. Moreover, increasing b substantially enlarges the photon sphere, impact parameter, shadow radius, and suppresses the observed disk brightness, while the magnetic charge g produces only negligible corrections completely masked by PFDM on macroscopic scales. Subsequently, we investigate the primary/secondary images, flux, and redshift profiles for the PFDM-Bardeen BH using the Novikov--Thorne disk model, and compare these quantities with those of NFW, Dehnen-type and Moore DM BHs. The four BH types exhibit distinct densities at the shadow radius and at 100 pc, offering a potential distinguishing signature. Furthermore, for all DM BH models, blueshift appears in the primary image as inclination increases, while the secondary image remains redshift dominated even at high inclinations. Hence, if significant blueshifted emission were detected at low inclination, the predictions of these four DM models would be seriously challenged.

In this paper, we generate a rotating charged black hole (BH) with scalar hair via the Newman--Janis algorithm (NJA) and study its thin accretion disk and shadow. The structure of the event horizon and ergosurface is analyzed in detail, revealing how the charge parameter Q and scalar hair parameter s influence the spacetime geometry. We analyze the energy flux and temperature distribution of the accretion disk, finding that increasing either Q or s leads to higher energy flux and peak temperature. The BH shadow is also examined, showing that its apparent size decreases monotonically with increasing Q or s. Notably, in the near-extremal regime, the shadow develops a distinctive cuspy edge, indicative of strong light bending in the scalarized and charged spacetime. By comparing the theoretically predicted shadow diameter with Event Horizon Telescope (EHT) observations of Sgr A*, we derive observational constraints on the model parameters. For inclination angles of 17<SUP>∘</SUP> and 90<SUP>∘</SUP>, a joint analysis constrains the charge parameter to 0 &lt; Q &lt; 0.522745 (at fixed <mml:math><mml:mrow><mml:mi>s</mml:mi><mml:mo>=</mml:mo><mml:mn>0.1</mml:mn></mml:mrow></mml:math>) and the scalar hair parameter to 0 &lt; s &lt; 0.283373 (at fixed <mml:math><mml:mrow><mml:mi>Q</mml:mi><mml:mo>=</mml:mo><mml:mn>0.3</mml:mn></mml:mrow></mml:math>). Our results demonstrate how scalar hair and electric charge leave imprints on accretion disk emissions and BH shadows, offering new observational signatures for testing gravity theories beyond general relativity.

The midfrequency gravitational-wave window remains largely uncovered, and atom interferometry with phase-accumulating large momentum transfer is a promising candidate to fill this gap. However, in previously proposed two-photon schemes, placing atomic ensembles on separate satellites breaks common-mode laser phase noise cancellation, creating a persistent dilemma between signal amplification and noise immunity. We resolve this trade-off with a differential dual-atom-interferometer architecture whose physical layout differs fundamentally from earlier designs. Two conjugate atom interferometers are collocated on a single platform, forming the hub of a three-satellite Michelson configuration, rather than being placed on separate satellites. This structural change enables a distinct measurement scheme in which cascaded composite Bragg pulses amplify the signal coherently, while the differential readout between the two collocated interferometers suppresses common-mode laser phase noise. To the best of our knowledge, this design is the first two-photon scheme to achieve high signal amplification and robust laser phase noise rejection simultaneously. It also provides the first quantum coherent phase accumulation and readout module based on differential measurement that can be directly integrated into existing laser interferometric observatories, such as Laser Interferometer Space Antenna and TianQin, enabling a hybrid multiband gravitational-wave detector.

We develop a theoretical framework for quantum field description of neutrino evolution in a medium, with a focus on quantum decoherence induced by neutrino scattering on fermions. By deriving a generalized Lindblad master equation that accounts for neutrino momentum-changing transitions, we go beyond the standard treatment that assumes fixed neutrino momentum. Our model explicitly connects decoherence parameters to scattering cross sections, offering a bridge between theoretical predictions and experimental constraints on neutrino quantum decoherence. We apply the developed formalism to several scenarios: (1) neutrino scattering on electrons, (2) neutrino scattering on protons and neutrons through nonstandard interactions, and (3) neutrino scattering on dark matter fermions. The obtained results demonstrate that decoherence effects can significantly alter neutrino oscillation patterns and provide a new probe for physics beyond the Standard Model.

We study a phenomenological fixed-ADM prescription for an extended-uncertainty-principle (EUP) correction to the Schwarzschild exterior. Rather than treat mass constancy as a consequence of the EUP, we hold the charge measured at spatial infinity fixed so that we can compare exteriors at the same physical mass. We impose the EUP-shifted horizon radius and Hawking temperature and select the slowest admissible inverse-power representative. Its Einstein tensor defines an effective anisotropic tensor, but we do not infer an independent matter model, quantum state, or perturbation theory from that definition. For a positive EUP parameter, the effective energy density is negative throughout the exterior, while the transverse null and strong energy conditions fail over an extended radial region. The area entropy and the formal entropy obtained from the reduced relation $\mathrm{d}M=T\,\mathrm{d}S$ disagree at leading order; we interpret this mismatch as evidence that the thermodynamic description lacks work terms or an action-based entropy law, not as a definite EUP entropy correction. An explicit one-parameter family with the same mass, horizon, and temperature shows that the orbit, lensing, and test-field eikonal shifts depend on the chosen representative. Our results therefore characterize the minimal member of a phenomenological family rather than universal consequences of the EUP.

Time-delay cosmography provides an independent probe of the Hubble constant ($H_0$), but exploiting the high-resolution imaging of the James Webb Space Telescope (JWST) requires strong-lens models that capture complex source-galaxy morphologies and the point spread function (PSF) with high fidelity. Flexible source and joint PSF reconstruction are computationally expensive, motivating more rigid parameterizations that can bias the inferred time-delay distance $D_{Δt}$. We present ALPACA, a semi-automatic, GPU-accelerated, differentiable strong-lens modeling pipeline built on Herculens, Starred, and JAX. ALPACA jointly reconstructs a pixelated correlated-field source, the lens mass, and the PSF within a single likelihood, reducing per-system runtimes from weeks to less than 15 hours. We validate the pipeline on realistic mock JWST/NIRCam observations built from morphologically complex COSMOS galaxy sources. Holding an imperfect PSF (RMSE = 12% from truth) fixed biases $D_{Δt}$ by up to 14%, whereas joint PSF reconstruction reduces this bias to the percent level. We further show that the reconstructed PSF core can be marginalized over jointly with the lens parameters during posterior sampling. Propagating the per-lens posteriors of a ten-lens mock sample through hierarchical inference, we recover the input cosmology without significant bias. ALPACA shows that rigorous control of source and PSF systematics is computationally affordable, supporting reliable percent-level precision in the JWST era.

The Dark Energy Spectroscopic Instrument is conducting a redshift survey, mapping the universe in three dimensions to measure the history of cosmic expansion. As well as extragalactic objects, it is targeting millions of Milky Way stars, including white dwarfs. Using Data Release 1 we assemble the largest catalogue of spectroscopically-confirmed white dwarfs to date, whose straightforward selection function enables statistically-robust population studies. We visually inspect and fit models to spectra of 63968 objects, finding 44409 white dwarfs. We present their spectral classifications, atmospheric parameters and radial velocities. We assess survey completeness and uniformity, identify potential spectral contamination caused by flux from nearby sources entering the fibre, and assign confidence scores to our classifications to facilitate selection of statistical and observational samples. We present spectra representing most white dwarf classes, common and exotic. We conclude with recommendations and warnings regarding the use of the catalogue.

Constraints on the effective viscosity of the intracluster medium (ICM) come almost exclusively from imaging: the power spectrum of X-ray surface brightness fluctuations, and the morphology of Kelvin-Helmholtz rolls at cold fronts. Both indicate a viscosity below the isotropic Spitzer value. XRISM/Resolve opens a complementary, purely kinematic route, in which the viscosity is inferred from the thickness of the viscous shear layer that develops at a sliding contact discontinuity. We apply it to the prototypical cold front of A3667. The interface is the classical Rayleigh problem, in which momentum diffuses to a depth d in a time T, giving a kinematic viscosity ν~ d^2/(4T). The XRISM velocity map shows a line-of-sight velocity jump of 535 km/s across the front, completed within the 100 kpc-wide region immediately inside it, the only region with an anomalously broad line. Hence d ~< 100 kpc. Adopting interaction times set by the sizes of the interacting regions divided by this velocity, we obtain dynamic viscosities of 5.2 x 10^3 and 3.3 x 10^3 g/cm/s for the cool and the hot side of the front, or 6.4 and 0.72 times the Spitzer value. Because d is limited by the angular resolution of XRISM, and the viscosity scales as its square, these are upper limits. The kinematic constraint is consistent with, and independent of, the imaging results.

White dwarf asteroseismology aims to constrain the interior structures of pulsating white dwarf stars by fitting observed pulsation periods to those computed for stellar models. However, there remain several obstacles for achieving reliable results with the model grid-fitting approach. We simulate data for a parameter recovery experiment in one and two dimensions (mass and effective temperature) to demonstrate improved methodologies that address challenges for characterizing degenerate asteroseismic solutions. We show that interpolating model periods onto a finer grid can adequately resolve asteroseismic solutions that would be missed with sparse model grids. Incorporating absolute magnitude from Gaia astrometry into the statistical fitting is shown to reduce solution degeneracy. We define a seismic solution as a solution to the mode identification problem, and we show that fitting to consistent model pulsation modes can isolate each candidate solution in degenerate solution space. A criterion based on $χ^2$ for what should be considered a reasonable fit is adopted, and we identify all combinations of model periods that meet this criterion, not only those nearest to the measured periods. Finally, we demonstrate how fitting Gaussians to probability distributions allows for the robust characterization of each candidate solution, including uncertainties. Our accurate characterization of the degenerate solution landscape is supported by the comparison of our solutions to a direct marginalization of the likelihood function. These fitting approaches can be generalized to higher dimensions, where there are more than two free parameters.

Cool-gas inflows, required to sustain star formation, have been fundamental in simulations yet remained observationally elusive. Using DESI spectroscopy of ~30,000 galaxies, we identify coherent inflowing gas (~100 km/s) in 20-50% of the sample, yielding a population-level census of gas flows. We uncover a striking inversion: inflows are detected in quiescent galaxies, whereas star-forming systems are dominated by gravitationally bound outflows. At fixed age, galaxies with inflows, outflows, or no/weak flows share similar masses, environments, and structures, indicating that these properties do not differentiate flow states. Instead, gas-flow state is linked to stellar population age and recent evolutionary history, consistent with age-dependent gas flows in two regimes. In some star-forming galaxies, elevated star formation surface densities drive outflows that recycle on ~0.5 Gyr timescales, consistent with a galactic fountain. In quiescent systems, low-level ``drizzling'' inflows persist, consistent with slowly cooling enriched halo gas and weak radio-mode nuclear activity. Broad gas-phase metallicity distributions---and absence of a pristine dilution signature---indicate that detected inflows are predominantly recycled or enriched. Detectability is modulated by dust, ionization, and geometry: in star-forming disks, inflowing gas lies near the disk plane and is obscured or ionized, while outflow hosts exhibit higher dust and metal content. As star formation declines, cold-outflow signatures weaken, and recycled or slowly cooling gas is more readily detected as inflow. Post-starburst galaxies provide snapshots of this transition. Our results resolve the scarcity of observed inflows, provide evidence for widespread gas accretion and recycling in present day galaxies, and establish an observational framework linking gas flows to star formation, chemical evolution, and galaxy structure.

H I gas traces the large-scale structure and provides the primary fuel for star formation. High-$z$ protoclusters are ideal laboratories to study how H I gas is accreted and consumed during the formation of the most massive structures in the Universe. However, much remains unknown about the distribution and physical state of their H I gas. We examine a rare configuration in which a protocluster candidate is located in front of a quasar at $z=3.09$. Our spectroscopic campaign confirms a protocluster at $z=3.079$: however, no corresponding strong H I absorption is found in the background quasar spectrum. Instead, we serendipitously discover a prominent H I absorption feature at $z\sim 3.01$, offset by $\sim 60$ cMpc from the centre of the protocluster. Spanning an exceptionally broad velocity range of $\sim 2000$ km s$^{-1}$ ($\sim 40$ cMpc), this absorption is decoupled from the confirmed member galaxies. Detailed kinematic modelling reveals this absorption comprises five distinct components rather than a single cloud. Moreover, one of these components exhibits a super-solar metallicity ($[\mathrm{O/H}] = +1.19^{+0.91}_{-0.78}$). We propose two physical scenarios for this unique system: (1) an additional, hidden massive protocluster along the line of sight, and/or (2) metal-rich outflows and metal-poor inflows driven by a single massive galaxy. The discovery highlights that while protoclusters are not universally associated with strong H I absorption, targeting the strong H I absorbers may serve as a beacon for uncovering massive, metal-rich protoclusters or complex gas kinematics in the early Universe.

The standard linearly perturbed Friedmann-Lemaître-Robertson-Walker (FLRW) framework provides an accurate description of the Universe on large scales but cannot fully capture the non-linear inhomogeneities that characterize the local Universe. In this work, we investigate whether an exact inhomogeneous solution of the Einstein field equations can provide a more realistic description of the nearby cosmic environment. To this end, we employ the quasi-spherical Szekeres class I solution with $Λ$ and focus on its axisymmetric subclass, motivated by recent observations indicating an axisymmetric expansion rate of the local Universe. We determine light propagation by numerically integrating the Sachs optical equations, thereby obtaining the luminosity distance and its evolution with redshift. We further compute the multipoles of the covariant cosmographic parameters and apply the formalism to an attractor-repeller configuration representative of the local matter distribution. We find that the resulting covariant cosmographic parameters are consistent with current observational constraints. Finally, we derive the gravitational potential and peculiar velocity field generated by the Szekeres density distribution, establishing the connection between the exact relativistic solution and its Newtonian counterparts.

We study the stability of collective neutrino oscillations using a distributional approach motivated by the statistical mechanics of Kuramoto synchronization. Treating the ensemble of neutrino flavor polarization vectors in the thermodynamic limit $N\to\infty$, we derive an exact nonlinear Fokker--Planck (continuity) equation for the one-body distribution $F(\vec{\mathbf{S}},ω,t)$ on the flavor sphere. This equation admits a two-parameter family of azimuthally symmetric stationary solutions, whose stability we analyze by linearizing around them. The resulting eigenvalue condition determines the growth or decay rate of small perturbations from \emph{any} initial distribution -- not merely from a state close to full flavor coherence -- thereby going significantly beyond the conventional linear stability analysis of collective modes. In special limits the condition reproduces known synchronization thresholds in the two-beam model, providing a non-trivial check of the framework. We present analytical results for the eigenvalue equation and explore stability phase diagrams for physically relevant frequency distributions.

Supermassive binary black holes (SMBBHs) are expected to be surrounded by circumbinary disks (CBDs) which affect the binary through gravitational forces and accretion. It has been reported that the binary can experience ``preferential accretion'' where one black hole (BH) out-accretes the other for hundreds of orbits, but this asymmetry has yet to be fully described or understood. In this work, we utilize a suite of 80 SMBBH hydrodynamical simulations with varying mass ratios ($q_b$) and eccentricity ($e_b$) in order to robustly delineate the behavior of preferential accretion, determine its relationship to the structure of the CBD, and study its observational consequences. We characterize the accretion-rate ratio $λ(t) \equiv \dot{M}_2(t)/\dot{M}_1(t)$ and the mass-ratio rate of change $\dot{q}_b \equiv d/dt(M_2/M_1)$ across the suite. We confirm that the secondary tends to out-accrete the primary ($λ\geq 1$), and find this preference to be strongest for low-$e_b$, low-$q_b$ binaries and increasingly time-variable toward high $e_b$. We also find that (i) the time-variability of $λ$ tracks the precession of the CBD, (ii) there can be sub- and super-Eddington accretion in a single binary, and (iii) the gas-driven approach toward equal mass becomes particularly slow for highly eccentric, high $q_b$ binaries, suggesting that some binaries may not reach $q_b=1$ within the $30\,\mathrm{Myr}$ lifetime of a quasar and therefore allowing LISA to constrain the accretion history of SMBBHs. Our findings also suggest that periodically flickering jets are a potential observable signature of many binaries.

We generalize the apparent-horizon thermodynamic construction of [1] to a FLRW universe with non-zero spatial curvature, non-interacting cold dark matter and holographic-type dark energy. For nonzero curvature, the scale factor is an additional geometric variable in the horizon equation of state. The usual criticality conditions are thus not well defined until a closure prescription for the curvature sector is provided. We introduce a dimensionless curvature variable and restrict the thermodynamic variations to slices of constant value of this variable. For each such slice, a positive holographic coupling and nonlinear powers larger than one guaranty the existence of a unique positive critical point. The critical specific volume, temperature and pressure are shifted by the spatial curvature, while the critical ratio and the mean-field critical exponents remain unchanged. It thus rescales the critical quantities, without generating a new local universality class. We construct a Helmholtz potential out of the physical thermodynamic volume and the entropy conjugate to the rescaled horizon temperature. In the quadratic holographic model, the parametric coexistence curve which is equivalent to the Maxwell construction is derived from the equality of the Gibbs free energies of the competing branches. The associated latent heat disappears at the critical endpoint, resulting in a global first-order coexistence in the fixed-curvature ensemble. Whether a physical FLRW trajectory intersects the critical or coexistence locus is a separate dynamical question because the dimensionless curvature variable generally evolves during cosmological expansion.

We present the first systematic investigation of the continuous orbital evolution of the Gigahertz-Peaked Spectum turnover frequency ($ν_{peak}$) in the binary millisecond pulsar, PSR J2144$-$5237. Using approximately 50 hours of densely sampled observations spanning the $\sim10$-day orbit with the Parkes Ultra-Wideband Low frequency receiver, we obtained continuous frequency coverage from 704 MHz to 4 GHz, enabling robust measurements of the spectral evolution throughout the binary orbit. We detect a clear and systematic modulation of the turnover frequency with orbital phase for both the $1^{st}$ pulse and $2^{nd}$ pulse components, with both emission components exhibiting remarkably similar evolutionary trends despite originating from distinct emission regions within the pulsar magnetosphere. The correlated evolution of the two pulse components strongly suggests that the observed spectral variability is governed by propagation through the intra-binary environment. The large orbital modulation of turnover frequency can be explained by cyclotron resonance absorption in magnetized plasma associated with the companion, while alternative absorption mechanisms are unable to reproduce the observed behaviour. Modelling the orbital evolution of the turnover frequency within the cyclotron absorption framework, can constrain the electron density distribution in the pulsar wind, estimate the magnetic field strength of the companion, and place limits on the geometry of the absorbing plasma and the binary system. This study establish orbital evolution of the Gigahertz Peaked Spectum as a powerful new diagnostic of the magnetized intra-binary medium and provide a hitherto unexplored probe of pulsar wind-companion interactions in eclipsing millisecond pulsar binaries.

We provide a pedagogical guide to help researchers choose an appropriate compression method for cosmological inference and numerical covariance estimation, trading off the balance between information loss and complexity. We describe methods used in the literature, categorising them by the form of the loss function -- Fisher information, mutual information, or mean squared error -- and by whether they are linear or non-linear. We consider in detail the linear compression methods: massively optimised parameter estimation and data compression (MOPED), canonical correlation analysis (CCA), principal component analysis, and linear neural networks. We also investigate simple non-linear methods based on neural networks with similar architectures but different loss functions. We use tomographic weak lensing power spectra as example data vectors, deriving constraints on the cosmological parameters $Ω_\mathrm{m}$, $σ_8$, $w_0$ and $w_a$ from compressed data. For our figure of merit (FoM) we use the log determinant of the Fisher matrix, which approximates the covariance of the full posterior well. MOPED and a Fisher information-based linear neural network both achieve lossless compression. Neural networks with loss functions which optimise mutual information achieve at most 84 per cent of the uncompressed FoM and those which minimise mean squared errors achieve at most 72 per cent. We show how to determine whether MOPED will retain information even if the fiducial cosmology is not known with certainty, and demonstrate a strategy for CCA which results in an FoM close to that of MOPED while requiring only an approximate idea of where the bulk of the posterior mass is located.

Context. Open clusters (OCs) are fundamental tracers for studying the structure and chemical evolution of the Galactic disc. Reliable identification of cluster members, particularly at the faint end of the main sequence, remains challenging owing to severe field-star contamination and the declining photometric completeness for distant, obscured systems. Aims. We aim to identify and characterise distant OC candidates at heliocentric distances $d \gtrsim 3$ kpc using Gaia DR3 astrometry, with emphasis on improving the recovery of faint candidate members in highly contaminated stellar fields. Methods. We apply a probabilistic membership method based on Gaia DR3 proper motions and parallaxes. Candidate members are selected through combined astrometric criteria and refined via spatial filtering using radial density profiles, with photometric data serving as a consistency check. For clusters affected by significant extinction, near-infrared photometry from 2MASS is incorporated to compensate for the limitations of optical data. Results. We analyse a sample of 45 targets, comprising 30 previously reported OCs and 15 newly identified candidates, all located at $d \gtrsim 3$ kpc. The method yields more compact astrometric distributions and improves the recovery of faint candidate members in several systems. However, residual field contamination remains non-negligible for the most obscured clusters projected against the Galactic plane. Conclusions. Gaia DR3 astrometry provides an effective basis for the exploratory identification and first-order characterisation of distant OC candidates. Dedicated near-infrared follow-up observations will be essential for robust membership assessment in high extincted regions.

We present an interacting scenario between dark energy (DE) and dark matter (DM), where DE has an emergent nature, that means, DE was absent in the early universe but it becomes effective only at late times. We consider two specific emergent DE models, one with no free parameters and the other featuring two parameters describing the speed and epoch of the transition. We constrain both scenarios using the cosmic microwave background (CMB) measurements from the Planck 2018 release, baryon acoustic oscillations from DESI DR2, and three different compilations of Type Ia supernovae (PantheonPlus, DES-Dovekie, and Union3). Our analysis indicates that current cosmological probes are not able to tightly constrain the speed of the transition. For both scenarios, the posterior distribution of the interaction parameter is shifted away from zero at more than 95\% CL whenever the CMB data are combined with any of these additional probes, with the preferred direction corresponding to a transfer of energy from DE to DM. While CMB alone yields a high value of $H_0$, in agreement with local determinations, this effect is reduced when DESI is added and disappears once supernova data are included. In contrast, the clustering parameter $S_8$ is consistently shifted toward lower values in the combined datasets, and it is correlated with the preference for a negative interaction. However, according to the $Δχ^2_{\rm min}$ and Bayesian evidence, none of the interacting models is favored over $Λ$CDM or $w_0w_a$CDM, indicating that the interaction does not rescue these emergent DE models. Our results therefore highlight the limitations of these scenarios in addressing current cosmological tensions, while pointing to the crucial role of future data in further assessing their viability.

Motivated by the strong cosmic censorship conjecture in general relativity, we prove the inextendibility of spherically symmetric weak null singularities as spherically symmetric Lorentzian manifolds with a continuous metric and Christoffel symbols in $L^{s}_{\text{loc}}$ for $s>1$. The result assumes a suitable blow-up condition on the derivative of the area-radius function transverse to the weak null singularity in combination with a rigidity result on continuous spherically symmetric extensions across null boundaries proven in [1]. In particular we show that these assumptions are satisfied by the Reissner-Nordström-Vaidya spacetime as well as by a class of spacetimes arising from small and generic spherically symmetric perturbations of subextremal Reissner-Nordström under the Einstein-Maxwell-scalar field system.

In this work, we construct a novel cosmological framework by integrating the running vacuum model into the Randall-Sundrum II braneworld scenario. We derive a special class of analytical solutions in the model. Our investigation focuses on the complete evolutionary trajectory of the universe, with particular emphasis on the realization of primordial inflation and the evolution of cosmic entropy. We evaluate the model's viability across three scenarios: dust-dominated, radiation-dominated, and general perfect fluid-dominated universes. Our findings show that while the hybrid model is in principle capable of supporting inflation, producing enough e-fold number demands either severe fine-tuning of the parameter or unreasonably large (and thus physically unnatural) value of the parameter.

Observations of Wolf-Rayet (WR) stars in binaries in the SMC and LMC suggest a preference for short period ($P\lesssim30$ days) orbits, with an apparent absence of WRs in long-period systems. The Galactic population does extend to longer periods but shows a deficit in long-period WR binaries compared to their progenitors, the O-star population. Across these populations a nearly constant binary fraction has been observed. We aim to characterize the population of WR binaries across a range of metallicity and determine the metallicity dependence of the formation of these systems, specifically focusing on the period distribution. We use detailed binary evolution models from POSYDON to predict the population of WR binaries at 0.01, 0.1, 0.2, 0.45, and $1Z_\odot$, analyzing the resulting period distribution and formation channels, while comparing them against the observed population in the SMC, LMC, and Milky Way. We find that the absence of wider WR binaries in the SMC, and potentially in the LMC, can be explained by stable, Case-B mass transfer only partially stripping the donor star, combined with WR winds at low metallicity being insufficiently strong to strip the remaining envelope. As a result, the long-period peak from Case-B mass transfer, present at Zsun, disappears at low metallicity. We additionally find that stable mass transfer (SMT) produces a short-period peak through Case-A mass transfer (P~5-10 days) that closely matches observations across metallicity. Furthermore, SMT and non-interacting systems are the dominant formation channels of WR binaries at all metallicities, with their relative contribution showing no metallicity dependence. This result implies that the SMT channel has the same metallicity-dependence as isolated WR formation. At the same time, we find that common envelope evolution primarily produces short-period ($P<1$ day) WR binaries with black-hole companions.

Recent findings from Dark Energy Spectroscopic Instrument (DESI) Baryon Acoustic Oscillation (BAO) measurements, combined with Type Ia supernovae and Cosmic Microwave Background (CMB) data, suggest potential parameter-level deviations from $Λ\text{CDM}$. However, parameter exclusions omit prior-volume penalties, whereas Bayesian evidence uncovers a stark dichotomy between early- and late-time dynamics. To quantify this effect, we perform a Bayesian model comparison that explicitly accounts for the cosmological epoch of dark energy dynamics, contrasting two schemes acting in opposite epochs of cosmic history: pre-recombination Early Dark Energy (EDE) and late-time Chevallier--Polarski--Linder (CPL), both measured against a baseline $Λ$CDM. We validate the learned harmonic-mean estimator against \texttt{UltraNest} (at background level) before applying it to the CMB analysis. Background-only data already disfavor both extensions, yielding $\ln B_{Λ\text{CDM},\text{EDE}} = 2.45 \pm 0.25$ and $\ln B_{Λ\text{CDM},\text{CPL}} = 3.45 \pm 0.24$. Including CMB sharpens this result: EDE is decisively rejected ($\ln B_{Λ\text{CDM},\text{EDE}} = 12.44 \pm 0.05$) with its early-time fraction constrained to $10^3\,Ω_e^{\rm EDE} = 2.0^{+0.6}_{-1.0}$, whereas CPL remains moderately disfavored ($\ln B_{Λ\text{CDM},\text{CPL}} = 2.33 \pm 0.06$), even though 2D parameter posteriors for both models display a multi-$σ$ deviation from $Λ\text{CDM}$. Thus, Bayesian evidence weakens reported preferences for dark energy dynamics, with the impact depending on the cosmic epoch involved, confirmed by our functional reconstructions of $w_{\rm de}(z)$ and $Ω_{\rm de}(z)$ from posterior samples.

Reconstructing the initial conditions of the Universe from late-time tracers would unlock cosmological information buried by non-linear structure formation and astrophysics. We reconstruct the initial density field at $z\sim300$ from simulated 21-cm and CO(1-0) line-intensity maps at $z\sim8$ generated with LIMFAST. Using a three-dimensional U-Net, we reconstruct the initial conditions and evaluate its impact on cosmological parameter constraints. The two tracers probe complementary environments: 21-cm emission traces neutral, low-density regions of the intergalactic medium, while CO traces overdense, star-forming regions. To emulate realistic observations, we model instrumental effects for SKA1-Low- and COMAP-ERA-like surveys, including finite angular resolution and thermal noise. We assess reconstruction performance through the cross-correlation coefficient between reconstructed and true initial density fields, $|C(k)|$. In the noiseless case, combining both tracers delivers the most accurate recovery across ionisation states, with $|C(k)| \gtrsim$ 0.90 for $k \lesssim$ 0.75 Mpc$^{-1}$. With observational effects, small-scale information is degraded, but combining tracers still achieves $|C(k)| \gtrsim$ 0.70 for $k \lesssim$ 0.3 Mpc$^{-1}$. To quantify information gain, we perform simulation-based inference of cosmological parameters from power-spectrum summaries before and after reconstruction. In both noiseless and noisy settings, reconstruction tightens parameter constraints: uncertainties on $σ_8$ and $n_{\rm s}$ improve by $\sim2\times$, with smaller but consistent gains for other parameters. This is further confirmed using Kullback-Leibler divergence diagnostics for an ensemble of observations. These results indicate that joint analysis of future 21-cm and CO surveys, combined with such reconstruction, can partially recover otherwise inaccessible cosmological information.

This paper provides the instability counterpart to our recent construction of nonspherically symmetric approximating $κ$-self-similar naked-singularity solutions for the Einstein--scalar field system. These singular solutions contain pervasive nonspherical borderline terms, and to prove instability the delicate renormalization procedure developed in [2] does not extend to the more singular setting considered here. To overcome these difficulties, we introduce a new iteration scheme adapted to singular backgrounds whose leading-order geometry depends on the angular variables. At each step, the nonlinear coefficients are frozen using the preceding double-null geometry, and the resulting equations are solved in a triangular order. In this way, the nonspherical borderline terms are incorporated into the approximate geometry rather than treated as perturbative errors, yielding successively sharper estimates. After sufficiently many iterations, the scheme controls the singular angular structure and produces an approximate spacetime whose difference from the exact solution satisfies the required bounds. In particular, these bounds provide an existence region large enough to carry out the instability argument. We further prove that anisotropic perturbations of the outgoing data, arbitrarily small in a scale-critical norm, lead to the formation of a trapped surface. We also formulate and verify a matter-focusing condition under which a parabolic flow argument guarantees the existence of a corresponding marginally outer trapped surface (MOTS). Together, these results establish the nonlinear instability of $κ$-self-similar naked singularities beyond spherical symmetry in the Einstein--scalar field system and introduce a framework for applications across Einstein systems.

Primordial non-Gaussianity (PNG) offers a powerful test of inflationary physics beyond the simplest single-field scenarios. In large-scale structure, biased tracers respond to local-type PNG with a distinctive scale-dependent signature that is strongest on large scales, but single-tracer measurements are fundamentally limited by cosmic variance. Multitracer methods can mitigate this limitation; however, many existing proposals require splitting tracers using a wide range of halo masses which are often not available, or using secondary halo properties that are not directly observable. Here we develop and validate an alternative strategy based on splitting a tracer sample by its large-scale dark matter environment. We derive a theoretical framework for the $f_{\rm NL}$ response of environmentally selected tracers and test it in $N$-body simulations, confirming consistency between separate-universe predictions and direct power-spectrum inference. To enable observational implementation, we show that a simple linear-theory reconstruction of the dark matter environment from halos yields unbiased $f_{\rm NL}$ constraints in $\mathtt{Quijote}$ simulations. Forecasts for the DESI LRG sample indicate that environmental multitracing can improve constraints on local PNG by a factor of 2-3 relative to conventional single-tracer analyses for high density tracers, comparable to gains achieved when halo formation time is assumed to be perfectly known. We develop an analytic model explaining why the gains are smaller for a halo environment split and why separate-universe predictions fail in this case. Unlike approaches that require modeling assembly bias or inferring secondary halo properties, our method relies only on linear theory. These results establish environmental multitracer techniques as a promising route toward $σ(f_{\rm NL})\sim 1$ with upcoming galaxy surveys.

We develop an analytical treatment of the emergent cosmological dynamics induced by local polynomial interactions in a deparametrised group field theory model, moving beyond the usual non-interacting approximation. For a single field mode with quartic and sextic couplings we obtain a closed-form generalised Friedmann equation within a controlled Gaussian regime. The dynamics preserves the quantum bounce while generating effective dark matter and dark energy contributions as collective quantum-geometric phenomena, providing the first derivation of both components from a single model. Matching the resulting dark-energy-to-dark-matter density ratio to observations places concrete phenomenological constraints on the fundamental theory, linking the cosmic coincidence problem directly to the underlying quantum gravity dynamics. Our results extend to arbitrary even polynomial interactions, establishing a systematic dictionary between microscopic interaction orders and effective equations of state.

The recent analyses of DESI DR2 BAO, Planck CMB and various Supernovae datasets have shown preferences for evolving dark energy at various levels of significance, under frequentist model comparison tests. However, the same analysis done with a pure Bayesian model comparison test can lead to the opposite conclusion due to the impact of $w_0w_a$ priors. In contrast to these in-sample model comparison route, we approach the problem along a third axis -- which model better predicts unseen data. We use the Expected Log Predictive Density (ELPD) metric to score the predictiveness of $Λ$CDM and $w_0w_a$CDM models, using the leave-one-redshift-block-out cross-validation estimator. The comparison metric $Δ$ELPD is out-of-sample, unlike $Δχ^2_{\rm MAP}$ and Bayes Factor, and insensitive to prior width, unlike the Bayes factor. Aggregated, we find modest preferences for $w_0 w_a$CDM, primarily driven by the BAO. Decomposing the $Δ$ELPD score by redshift we find that a single BAO block, LRG2 ($z = 0.706$), supplies the entire BAO preference. Interestingly, the biggest outlier point, LRG1, contributes little to the model predictive scoring because both $Λ$CDM and $w_0w_a$CDM fail to predict the observation by equal amount. On the other hand, all SNIa datasets' $Δ$ELPD scores are consistent with $0$, indicating that at an out-of-distribution predictive level, the $w_0w_a$CDM tension is entirely driven by one BAO point, not SNIa.

We develop a branch-complete classical free-spectrum analysis of local parity-even symmetric teleparallel gravity containing all pure-gravity nonmetricity operators through four derivatives. After canonicalisation and integration by parts, the nonlinear action contains 116 independent operators distributed as $5+13+29+69$ among $Q^2$, $(\nabla Q)^2$, $Q^2\nabla Q$ and $Q^4$. Around Minkowski spacetime in the coincident gauge only the first two sectors contribute to the quadratic action, which reduces to four two-derivative and five four-derivative bilinears. We map the original coefficients to this nine-dimensional basis, construct the Hessian and momentum kernel, and classify local linear gauge symmetries. Unrestricted linearised diffeomorphism invariance imposes six independent relations and leaves a three-parameter family $(A,B,C)$. We also recover TDiff, Weyl, WTDiff and additional accidental symmetry branches. Barnes--Rivers decomposition, gauge fixing, exact inversion and conserved-source saturation reduce the physical exchange to spin-two and scalar factors $A+2Cq$ and $2A+(3B-2C)q$. The generic regular spectrum contains a massless graviton, a massive spin-two state and a massive scalar, with eight degrees of freedom. The massive spin-two residue is necessarily opposite to that of the healthy massless graviton. The regular classification leaves only GR/STEGR, $A>0$ with $B=C=0$, and the scalar extension, $A>0$, $B>0$, $C=0$, as fully healthy Minkowski loci. The latter has three degrees of freedom and mixed ultraviolet behaviour, with tensor exchange scaling as $k^{-2}$ and scalar exchange as $k^{-4}$. Thus, within this finite local metric theory, full four-derivative tensor suppression requires the finite massive spin-two pole with opposite residue.

In this work, we investigate exactly the dynamics of a relativistic spinless particle influenced by a static and uncharged black hole surrounded by a quintessence-like anisotropic fluid or Kiselev black hole. Considering two quintessence-like models as examples, we calculate the radial wave function and determine, in both cases, the quasispectrum of energy, as well as the Hawking radiation and temperature. We find that the stronger the influence of quintessence-like anisotropic fluid, the smaller the radiation observed outside the event horizon. Furthermore, the temperatures obtained in both cases are directly influenced by the quintessence-like anisotropic fluid, and we recover the values obtained in other contexts, such as those derived using the surface gravity. Finally, in the absence of quintessence, we recover in both cases the Hawking temperature $T_{H} = 1/(8πk_{B} M)$ corresponding to the Schwarzschild black hole.

In this work, we provide the first derivation of the line-intensity mapping (LIM) power spectrum super-sample covariance (SSC) from first principles, and also derive as a by-product the non-Gaussian in-box contributions to the covariance for the first time. Previous studies have typically modelled the LIM power spectrum covariance using either the Gaussian approximation or estimates obtained from mocks or the data itself, neglecting uncertainties related to whether the limited volume surveyed sits in a cosmological overdensity. This contribution, known as the SSC or, depending on the context, the field-to-field variance, cannot be estimated from the data, but it is crucial for a correct inference of global quantities, i.e., for ensemble-averaged parameters rather than the actual values just within the patch of the Universe observed. For our derivation, we employ a combination of the halo model and standard perturbation theory that allows us to capture the nonlinearity and non-Gaussianity of the covariance. After a successful validation of our predictions against painted N-body simulations, we explore different scenarios related to current and future LIM experiments, quantifying the relative importance of the non-Gaussian in-box and SSC. We find that the newly derived contributions to the LIM power spectrum covariance are crucial at intermediate and small scales, especially for cases in which the covariance is not dominated by instrumental noise. We find that the relative relevance of the SSC with respect to the other covariance contributions is roughly independent of the survey volume, but does depend on the specific response of the power spectrum to large-scale modes for each line and redshift. Therefore, the impact of the SSC will be increasingly significant for parameter inference from the current and the next generation high signal-to-noise LIM surveys.

Recently, a new Trojan Horse Method (THM) measurement of carbon-carbon fusion was reported by Li \textit{et al.} [Phys. Lett. B (2026) 140675]. The purpose of the present work is to demonstrate the breakdown of the plane-wave approximation used in the analysis of these data and the critical role of Coulomb distortions in the initial and final states. The reaction mechanism underlying the THM analysis of the $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion reaction using the $^{16}\mathrm{O}+{}^{12}\mathrm{C}\to α_s+α+{}^{20}\mathrm{Ne}$ reaction is investigated. Particular attention is paid to the spectator momentum distribution and to the dependence of the THM reaction amplitude on the relative carbon-carbon energy $E$. It is demonstrated that agreement with the measured spectator momentum distribution does not by itself validate the plane-wave approximation. Although the experimental momentum distribution can be reproduced, inclusion of Coulomb distortions in both the initial and final channels leads to an energy dependence of the THM amplitude that is completely different from the plane-wave result. Consequently, the energy dependence of the $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion cross section extracted from the THM data can be strongly distorted by the plane-wave treatment. It is concluded that the astrophysical factor extracted in the plane-wave analysis cannot be regarded as reliable and may lead to misleading conclusions concerning the low-energy $^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion reaction.

Parametric component separation methods used in cosmic microwave background (CMB) analyses commonly assume instrumental noise to be uncorrelated between frequency channels. This approximation may become insufficient for experiments whose design naturally introduces cross-channel correlations, such as interferometric or multi-band bolometric systems. This work aims to provide a consistent framework to include frequency-correlated noise in Commander2 and to quantify its impact on component separation in controlled and instrument-motivated simulations. We generalized the amplitude sampling of the Commander2 framework to consistently handle dense frequency-frequency noise covariance matrices, modifying the likelihood evaluation and parallel architecture. The implementation is validated on low-resolution simulations of a simplified CMB-S4-like configuration. We applied the generalized framework to instrument-motivated simulations of the QUBIC bolometric interferometer, using representative noise models derived from end-to-end simulations. Validation tests show excellent convergence and agreement between sampled parameters and analytical maximum-likelihood estimates. Accounting for frequency correlations reduces the width of the maximum-likelihood residual distributions by up to 8% on average, and up to 11% for individual parameters, relative to the diagonal-noise approximation. In QUBIC-based simulations, accounting for an anti-correlated noise produces posterior widths reduced by about 60%, while a positive-correlation test increases them by about 40%. This shows that neglecting cross-channel correlations can lead to incorrect posterior estimates in either direction. The generalized implementation presented here enables the Commander2 software to consistently propagate such correlations into parameter estimation, providing a framework for assessing their impact in future CMB analyses.

The gas-giant planet-metallicity correlation plays a fundamental role in our understanding of planet formation. We determine in a homogeneous way the metallicity and individual abundances of a sample of A and early-F stars, with and without known planetary companions, and discuss their abundance distribution and trends. We find that stars with planets generally exhibit higher abundances of both iron-peak and volatile elements compared to stars without known planets although in most cases this tendency is not statistically significant. The $\rm {C/O}$ ratio remains similar between both samples, while the $\rm {Mg/Si}$ ratio is shifted towards higher values in the general planet host sample. When the sample is limited to fully radiative stars (spectral type earlier than F5), the statistical significance of carbon overabundances vanishes. In contrast, elements such as O and Ni remain significantly overabundant. The $\rm {C/O}$ and $\rm {Mg/Si}$ ratios in this radiative subsample are statistically indistinguishable from that of the comparison sample. The persistent overabundance of O and Ni, combined with $\rm {C/O}$ and $\rm {Mg/Si}$ ratios similar to those of stars without planets in fully radiative hosts, points to the ongoing surface pollution by volatile-poor, silicate-rich rocky debris, rather than the accretion of gas giants. These findings might position early-type main-sequence stars as a crucial dynamical missing link in the chemical life-cycle of planetary systems: bridging the initial dust-trapping phase in pre-main sequence transition discs, the dilution of this superficial pollution during the fully convective red giant phase, and the eventual dynamically-driven accretion of asteroid material observed in polluted white dwarfs

Within the $1+1+2$ covariant formalism, we investigate Locally Rotationally Symmetric (LRS) class III spacetimes sourced by a self-gravitating Dirac field expressed in polar form. By recasting the covariant field equations into an autonomous dynamical system, we perform a phase-space analysis of their solutions. We show that the cosmological evolution asymptotically converges to a contracting Bianchi I spacetime, a result also supported by numerical integrations of the system.

The Euclid spectroscopic survey will measure galaxy clustering with unprecedented precision, requiring stringent control of observational and instrumental systematics. Star-related effects may contaminate spectroscopic images through photometric persistence and imperfect masking of stars. We characterized their impact on galaxy clustering analyses, focusing on angular features identifiable in the data. We used angular and spatial auto- and cross-correlation statistics. For galaxies, we used mock spectroscopic catalogues from the EuclidLargeMocks in a 330 deg2 region of the Euclid Wide Survey (EWS). For stars, we used Gaia and 2MASS catalogues in the same area. To simulate photometric persistence, we implemented a simplified detector-level model calibrated on spectroscopic measurements and varied its strength to introduce different interloper fractions. For stellar masking, we modelled inconsistencies between the mask applied to the data and to the random catalogue. We measured star-star, galaxy-galaxy, and star-galaxy angular correlation functions using the Landy--Szalay estimator, and quantified deviations from the expected null star-galaxy correlation. We also evaluated the large-scale impact of such systematics through the three-dimensional two-point correlation function (2PCF). Photometric persistence produces a characteristic feature in the star-galaxy angular cross-correlation at scales of order 100", corresponding to the Euclid dithering pattern and grism dispersion geometry, and a spurious positive signal approximately constant up to 1°. Star-galaxy cross-correlation can detect residual persistence at contamination levels as low as 10% in a Data Release 1 spectroscopic catalogue. In contrast, stellar-mask mismatches produce strong small-scale angular signatures but have negligible impact on the large-scale 2PCF under realistic EWS conditions.

It is a problem of great importance in quantum gravity whether quantum effects lead to nontrivial structure near black hole horizons, and if their interiors are emergent features of a large $N$ limit. We show that the strongly chaotic nature of black holes, captured by random matrix statistics of their spectrum, makes it so that a suitably gravitationally dressed infalling observer takes an infinite amount of proper time to reach the horizon. This makes the black hole interior operationally inaccessible to any outside observer, marking a sharp breakdown of the large $N$ causal structure of black holes in quantum gravity. To model the experience of an infalling observer, we study the response of an infalling particle detector coupled to a matter field in a 2d quantum black hole background, finding a peak in the detector's excitation probability as it enters an infinitely long non-perturbative journey close to the black hole horizon.

We show new results of a global 3D magnetohydrodynamic (MHD) simulation of the Boston University outer heliosphere model where we used a newly developed approach that distributes the non-adiabatic shock heating among the cold protons, electrons, and pickup-ions (PUIs), while maintaining total energy conservation of all ions (cold protons and PUIs) and electrons. In our previous simulations ( E.S. Bair et al. 2025; B. van der Holst et al. 2026), all non-adiabatic shock heating was channeled to the cold protons, resulting in a too large temperature jump at the termination shock (TS) for the thermal solar wind. Using a new methodology we improved the simulation results with respect to the temperature jump observed at the TS by Voyager 2 (V2) spacecraft. Our simulations approached the observed jump conditions of a factor 10--20 in the cold solar wind temperature V2 measurements, and we obtain improvements in the simulation results relative to the data. Because we directly estimate in this way the distribution of non-adiabatic heating at the TS, we have the opportunity to study the physical process of heating cold plasma and PUIs in the TS. The results show that having almost 100\% non-adiabatic shock heating going towards PUIs at the TS reproduces the jump conditions observed along the V2 trajectory. This information is key to understanding the physical processes that shape the heliosphere. As shown by M. Opher et al. (2020), PUIs significantly change the shape of the heliosphere, for example, the presence of hot PUIs results in a deflated inner heliosheath. Our work provides the architecture of how energy partitioning at shocks in kinetic simulations (J. Giacalone et al. 2021) can be utilized in global MHD models.

We introduce ROCKETS (Rocket-driven Cluster Kinematics & Triggered Star-formation), a Gaia based programme investigating kinematic fingerprints of stellar feedback or rocket effect in young star forming regions. We analyse two young clusters with O-type stars enclosed by mid-infrared bubbles, Collinder 69 and IC 1396 as a methodological demonstration on two nearby benchmark regions. Co-moving candidates are selected within an astrometric ellipse defined by the median and median absolute deviation of Class I/II YSOs with Gaia data. For each star, we compute a relative proper-motion angle (RPMA) relative to the ionising source. In both regions the RPMA distribution shows a strong excess at RPMA $<15^{\circ}$, corresponding to sources moving away from the respective ionising sources. We quantify this using the Rocket Effect Index (REI), finding $\mathrm{REI}\simeq 1.1$ for Collinder 69 and $\mathrm{REI}\simeq 1.7$ for IC 1396. When considering only Class I/II YSOs, the REI of both regions increases to $\mathrm{REI}\gtrsim 10$. Velocity-structure analysis of the sample shows that the RPMA $<15^\circ$ subset has stronger positive pairwise expansion than the full co-moving population, providing additional support for the rocket effect. The outward-moving stars are not uniformly distributed; instead, their position angles are strongly anisotropic and preferentially aligned towards the bright-rimmed clouds. Gaia colour-magnitude diagrams show no strong age offset between sources moving outward and literature cluster members. The observed kinematic signatures support feedback-driven acceleration of gas and triggered star formation preferentially towards higher density regions of expanding bubbles due to the rocket effect.

In a scalar effective field theory (EFT) with Galileon symmetry, we distinguish the strong-field expansion from the derivative expansion and study spherically symmetric classical nonlinear dynamics. More concretely, we consider two models related via perturbative field redefinitions: one with second-order equations that can also exhibit screening, and one that includes a higher-derivative term that introduces a propagating ghost. The latter term is of the type that can ``regularise'' the equations to render them well-posed as an initial value problem. For initial data that respect the derivative expansion, we find that the first model (ghost-free, unregularised) develops ill-posed regions during evolution only when the derivative expansion breaks down. This result persists in the strong-field regime. We further find that the regularized model reproduces the evolution of the unregularised one when the latter remains well-posed, while it exhibits tachyonic behaviour when the unregularised one becomes ill-posed. We also consider initial data that corresponds to stationary states that exhibit screening in the unregularised, ghost-free theory. In this case, we find that the regularised theory can remain well-posed for initial data that the unregularised one developed ill-posed regions. However, the ghost term naturally dominates over the Galileon term in the screening regime, contrary to common expectation.