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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 12 May

Solar and Stellar Astrophysics

Effect of Solar Flares on Decayless Kink Oscillations in Nearby Coronal Loops

Zhiyi Li, Valery M. Nakariakov, Ding Yuan et al. (+1 more)

We present a statistical study of 130 solar flares (B to X class) that lack soft X-ray quasi-periodic pulsations and show no kink oscillations of nearby coronal loops visible in SDO/AIA 171~Å~images. The aim is to investigate whether decayless kink oscillations of coronal loops respond to nearby flaring activity. Using the Fractional Anisotropy-based Video Motion Magnification technique, we detected low-amplitude decayless oscillations in all 130 loops before, during, and after each flare, confirming their ubiquitous nature. Oscillation periods are found to range from 122~s to 268~s, and the projected displacement amplitudes are 0.023–0.111~Mm. No amplitude–period correlation is found. For each event, we estimated the amplitude before, during, and after the flare. Across all flare classes, the average amplitude remains unchanged. However, in some specific cases, the oscillation amplitude may exhibit minor changes. For B-, C-, and M-class flares, the fraction of events with an amplitude change exceeding 10% is approximately 23%, 41%, and 36%, respectively. In M-class flares, such minor amplitude increases occur four times more often than decreases; in X-class flares (only six events), decreases dominate by a factor of three. The fraction of events that exhibit an increase in the amplitude of more than 20% appears to be highest when the loop centre is located at a distance of 100–120~Mm from the flare site, reaching 33% (6 out of 18 events). Overall, the amplitude of decayless kink oscillations does not undergo a major change in response to nearby flares, especially for less powerful classes, suggesting that flare-related processes such as blast waves and reconnection inflows have little effect on the energy supply to oscillating loops.
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All authors Zhiyi Li, Valery M. Nakariakov, Ding Yuan, Song Feng

Cosmology and Nongalactic Astrophysics

Ultra-light axion constraints from Planck and ACT: the role of nonlinear modelling

Lauren Gaughan, Anne M. Green and Adam Moss

We study how constraints on the abundance of ultralight axions (ULAs) from cosmic microwave background (CMB) data depend on their nonlinear modelling. We focus on the axion mass range $10^{-25} \leq m/\rm{eV} \leq 10^{-23}$, where the axion Jeans scale falls in the quasi-linear regime probed by CMB lensing, making constraints highly sensitive to the choice of nonlinear prescription. We show that the inferred constraints depend significantly on the choice of nonlinear model, which must therefore be treated carefully. Performing Markov Chain Monte Carlo (MCMC) analyses with \Planck\, 2018, ACT DR6 and DESI DR2 BAO data, we find naive nonlinear modelling of non-cold matter can produce an artificial preference for a subdominant ULA dark matter component with mass $m \approx 10^{-24}\,$eV. This arises from a lensing-like enhancement of the CMB power spectrum.
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Solar and Stellar Astrophysics

An eclipsing CEMP candidate discovered in a search for dwarf carbon stars in post-common envelope binaries

Jonathan A. G. McLennan, Jay Farihi and Steven G. Parsons

Dwarf carbon stars are dominated by members of the Galactic halo and are thus likely carbon-enhanced metal-poor stars. In this work, 879 bona fide dwarf carbon stars are characterized by their ground-based light curves, and p < 15 d modulation is found to be significant in 31 objects (3.5 per cent), consistent with starspots and rotation in tidally-locked, post-common envelope binaries. Among these is an unambiguous halo star that is eclipsing every 1.224 d, and where the 30 per cent eclipse depth rules out a white dwarf occulter. Available Gaia data do not indicate any tertiary in the eclipsing system, but this remains a possibility and follow-up data are necessary to determine the evolutionary history of this first eclipsing binary among carbon-enhanced stars. Four of the variable sources exhibit clear multi-year, quasi-sinusoidal trends indicative of magnetic-activity and starspot cycles in rapidly-rotating, dynamo-rejuvenated stars. These data support a picture where carbon pollution results from wind capture prior to Roche lobe overflow, and the orbital period distribution appears to be moderately shifted to longer periods than carbon-normal, low-mass stars in similar binaries. The band-combined approach adopted in this work may be more sensitive than prior work using single-bandpass light curves, where at most 19 of 34 binary candidates previously published are independently confirmed here.
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High Energy Astrophysical Phenomena

A phenomenological model of the magnetic field re-emergence in magnetars and discrepancy between the kinematic and characteristic ages

Rostislav D. Nikandrov and Sergei B. Popov

Robust age measurements for isolated neutron stars (NSs) are not easily available. That is why, often the characteristic age $\tau_\mathrm{ch}=P/2\dot P$ is used as a proxy. Here $P$ is the spin period of the NS and $\dot P$ is the time derivative of $P$. Additional assumptions related to the initial properties and spin-down evolution are made to derive $\tau_\mathrm{ch}$. As a result, it is expected that $\tau_\mathrm{ch}$ is an upper limit for the real age $\tau_\mathrm{real}$. Recently, Chrimes et al. presented measurements of kinematic ages $\tau_\mathrm{kin}$ for several magnetars. Surprisingly, for the majority of these sources $\tau_\mathrm{kin}>\tau_\mathrm{ch}$. We present a simple model including a realistic approximation for the magnetic field decay in magnetars and a simple phenomenological description of the field re-emergence after an episode of fallback after the birth of a NS. We demonstrate that this simple model can explain the observed relation $\tau_\mathrm{kin}>\tau_\mathrm{ch}$ for realistic sets of parameters.
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Instrumentation and Methods for Astrophysics

Marginal multi-object multi-frame blind deconvolution

A. Asensio Ramos

High-resolution ground-based solar imaging relies heavily on multi-object multi-frame blind deconvolution to correct for atmospheric turbulence. However, the traditional joint maximum likelihood estimation methods in which object and the atmospheric aberrations are estimated together face some problems. In this paper, we introduce a marginal estimator for the multi-object multi-frame blind deconvolution problem. By employing a framework to marginalize over the observed objects, we develop a reconstruction method that offers several distinct advantages over joint estimation. First, the marginalization provides enhanced regularization that naturally accounts for object uncertainty, successfully preventing the reconstruction algorithm from erroneously assigning noise to high-order aberrations. Second, the marginal estimator yields more contrast control, as it is much less sensitive to the hyperparameters dictating the power spectral density (PSD) of the object. This robustness allows these hyperparameters to be optimized, enabling a “plug-and-play” deployment that removes the need for manual tuning. Finally, we demonstrate that the proposed method is accessible and simple to implement, requiring only the addition of a log-determinant term to the traditional merit function. With minimal modifications required for existing blind deconvolution pipelines, the estimator has been fully integrated into the open-source torchmfbd package for its use by the solar physics community.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

The choice of variables in cosmological dynamical systems

Christian G. Boehmer and Antonio d'Alfonso del Sordo

Dynamical systems techniques are a powerful tool to analyse systems of ordinary differential equations, written in an appropriate form. For a given theory of gravity, the cosmological field equations typically lead to a system of ordinary differential equations. Casting these cosmological equations into the form of a dynamical system requires a careful choice of the dynamical variables. Despite this being a critical step, relatively little is said about this process in the literature. We discuss how different variable choices affect the information that can be extracted from the Friedmann equations. We begin by reviewing the standard cosmological model with dark matter, radiation, and dark energy, and include quintessence models. We revisit well-known models with an exponential potential using new variables. This discussion is then extended to models with scalar fields and more intricate coupling terms.
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High Energy Astrophysical Phenomena

Limit on high energy neutrino emission from Abell 119 using IceCube 10-year muon track data

Sri Devaki Meduri and Shantanu Desai

We carry out a search for high energy muon neutrino emission from the galaxy cluster Abell 119, motivated by a recent tentative detection of GeV gamma-ray emission from this cluster using the Fermi-LAT telescope, which hinted at a hadronic origin. For this purpose, we used the 10-year muon track data from 2008-2018, provided by the IceCube Collaboration and implement the unbinned maximum likelihood method. We do not find any statistically significant excess and the observed value of the test statistic is consistent with a null result. We then obtain upper limits (at 90% confidence level) on the differential muon neutrino energy flux from this cluster, whose value is equal to $1.2 \times 10^{-9}~\mathrm{GeV}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$ at a pivot energy of 100 TeV, after assuming a neutrino spectral index of 2.0. The neutrino flux expected under the hadronic interpretation is, however, approximately an order of magnitude smaller than our flux limit, and hence the hadronic model cannot be ruled out based on our upper limit. Among the next generation neutrino detectors, IceCube-Gen2 and TRIDENT neutrino detector should be able to confirm or rule out a hadronic origin for the gamma-ray emission in Abell 119 with 10 years of exposure.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Probing the small-scale primordial power spectrum via relic neutrinos and acoustic reheating

Giovanni Piccoli, Sunny Vagnozzi and Joseph Silk

We show that the dissipation of small-scale perturbations through diffusion damping after neutrino decoupling lowers the present-day neutrino temperature compared to the expected value of $1.96\,{\text{K}}$. This reduces the relic neutrino abundance by an amount controlled by the integral of the primordial curvature power spectrum $\Delta_{\cal R}^2(k)$. We find that a relic neutrino detection by PTOLEMY can set limits $\Delta_{\cal R}^2(k) \lesssim {\cal O}(0.1)$ on scales $k \lesssim 3 \times 10^5\,{\text{Mpc}^{-1}}$, complementary to limits from Big Bang Nucleosynthesis, spectral distortions, pulsar timing arrays, and future dark ages 21-cm observations.
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High Energy Astrophysical Phenomena

Inferring host environment properties and gravitational-wave decay time from the eccentricity measurement of dynamically captured binaries

A. Vincent Paul, Parthapratim Mahapatra, Marc Favata et al. (+1 more)

Dynamical capture in dense stellar environments is a promising channel for producing eccentric compact binary mergers. Although there have been no confident detections of eccentric mergers to date, a few candidates show indications of non-negligible in-band eccentricity upon re-analysis of the data. By assuming an observed eccentric event originates from a dynamical gravitational wave (GW) capture, we show that it is possible to identify the host environment using the eccentricity and mass posteriors. In particular, the eccentricity posterior can be mapped to posteriors on key capture parameters, such as the relative velocity at infinity and the impact parameter. By comparing these with the expected velocity distributions of different astrophysical environments, we can place constraints on the likely host. Assuming that it originated from a GW capture, we applied this framework to the neutron star-black hole merger GW200105. By comparing with the velocity dispersion distributions of neutron stars in the cores of globular clusters (GCs) and nuclear star clusters (NSCs), we find the probability that GW200105 merged in a GC (NSC) to be 29% (71%). As we anticipate detecting several eccentric mergers in the future, this method can provide a valuable astrophysical diagnostic of their host environments on a single-event basis; this can be straightforwardly generalized to a population of eccentric binaries. The formalism we develop is also applied to GW190521, but is less constraining for that event. Lastly, we infer a GW decay time from capture to merger of 11-156 days for GW200105.
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All authors A. Vincent Paul, Parthapratim Mahapatra, Marc Favata, K. G. Arun

High Energy Astrophysical Phenomena

High-energy Neutrino and Gamma Ray Emission from Clusters-like Perseus

Saqib Hussain, Gabrijela Zaharijas and Klaus Dolag

We calculate the high-energy gamma-ray and neutrino emissions from galaxy clusters like Perseus that host active galactic nuclei (AGNs). Our primary objective is to distinguish the emission from the central source, such as NGC$1275$, from the diffuse emission originating in the outskirts of the Perseus cluster. Due to a unique magnetic-field configuration, CRs with energy $\leq 10^{17}$ eV can be confined within these structures over cosmological time scales, and generate secondary particles, including neutrinos and gamma-rays, through interactions with the background gas and photons. We employ three-dimensional cosmological magnetohydrodynamical simulations of structure formation to model the turbulent intracluster medium (ICM). We propagate CRs in intracluster medium (ICM) and intergalactic medium using multi-dimensional Monte Carlo simulations, considering all relevant photohadronic, photonuclear, and hadronuclear interactions. We also include the cosmological evolution of sources like Perseus. By comparing our results with the existing upper limits from IceCube for galaxy clusters and the sensitivity of CTA, we predict that these observatories could potentially establish a new class of astrophysical sources capable of emitting high-energy multi-messenger signals. We also compute the contribution from clusters like Perseus to the diffuse neutrino and gamma-ray background.
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High Energy Astrophysical Phenomena

High-energy Multi-messenger Emission from Galaxy Clusters in the Local Universe

Saqib Hussain, Gabrijela Zaharijas and Klaus Dolag

The origin of diffuse neutrinos and $\gamma$-rays is unknown, and galaxy clusters hosting AGN and starburst galaxies are the most probable sources of these cosmic messengers. In this work, we investigate the diffuse $\gamma$-ray and neutrino emission from the Virgo, Perseus, and Coma clusters using a detailed numerical method, combining MHD simulations with Monte Carlo methods. The MHD simulation provides the distributions of temperature, gas, and magnetic field in clusters. The Monte Carlo simulations are used to investigate the cosmic-ray (CR) propagation in ICM and subsequently the secondaries stemming from CRs. Our primary assumption is that CR injection scales with the gas density of clusters, providing a physically motivated approximation. High-density regions in clusters are associated with strong turbulence and prominent shock structures, making them natural sites for efficient CR acceleration. Our predicted $\gamma$-ray flux from the individual clusters lies well below the present LHAASO upper limits. The MAGIC observations of the central source NGC $1275$ of the Perseus cluster are significantly higher than our results. Further, we estimated the cumulative $\gamma$-ray and neutrino fluxes from clusters with masses $\gtrsim 5\times 10^{13}, M_{\odot}$ in the local Universe (within $500$ Mpc). The diffuse $\gamma$-ray flux reported by the Fermi-LAT collaboration is significantly higher than our results. Our predictions are consistent with IceCube's existing upper limits on the unresolved neutrino flux from galaxy clusters ($M > 10^{14}, M_{\odot}$) up to $z = 2$.
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Instrumentation and Methods for Astrophysics

Real-time detection of solar flares from ground-based VLF data

Pauline Teysseyre, Carine Briand and Morris Cohen

A method for real-time solar flare detection and characterization using ground-based Very Low Frequency (VLF, 15-45 kHz) data is presented. The D-region, the ionosphere's lowest region, is monitored by VLF waves propagating in the Earth-Ionosphere waveguide. The D-region electron density increases during sudden surges in X-ray radiation from solar flares. This subsequently enhances HF absorption. By seeking trend changes in VLF phase data, an incremental algorithm finds solar flares. 82.7% of M and X solar flares are detected within one fourth of their rise time. In addition, several VLF transmitters are monitored simultaneously. Combining information from their phase variations leads to an estimation of the Sun's X-ray flux. Last, propagation models such as LMP or LWPC are combined with the VLF measurements to compute D-region electron density profiles. This method and its implementation in a new Python package are a step towards building a more resilient system for flare detection and alerts. Its reliance on ground-based data alone ensures an easy maintenance and a backup in case a satellite failure. It also provides alerts comparable to or faster than those obtained through satellite data, due to shortened data latency.
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Earth and Planetary Astrophysics

Reaccumulation process after a catastrophic disruption event on a differentiated asteroid

Kenji Kurosaki and Masahiko Arakawa

Rubble-pile asteroids can form through the self-gravitational reaccumulation of fragments produced during large-scale collisions. To investigate how differentiated bodies are disrupted and how iron-rich rubble piles may form, we performed smoothed particle hydrodynamics simulations of impacts between differentiated asteroids with molten or solidified interiors. Our results show that catastrophic disruption produces a sheet-like structure in which core and mantle materials are stretched and subsequently fragment under self-gravity. The resulting fragments exhibit nearly identical iron-rock mass ratios, indicating that catastrophic disruption naturally generates numerous compositionally similar fragments. The largest remnant formed in such events is therefore an iron-rich rubble pile assembled from these mixed fragments, whereas remnants formed through mantle stripping retain a layered structure with an iron core and rocky mantle. We further find that fragment production is sensitive to material strength and the equation of state: mantle strength reduces the number of small fragments, while core strength suppresses catastrophic disruption when the core is solid. These results imply that iron-rich rubble-pile asteroids can form only when the iron core is molten. Our findings provide a unified framework for the formation of metal-rich asteroids such as (16) Psyche and the (22) Kalliope system, and offer predictions for the surface and internal structure that the NASA Psyche mission may test.
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Earth and Planetary Astrophysics

Simulation of the spin evolution of some selected exoplanets and inferences on their climate

Salvatore Camposeo, Francesco De Paolis, Vincenzo Orofino et al. (+2 more)

In this work, using the simulator VPLanet, we analyze the spin evolution of some selected exoplanets due to the tidal interaction with their host star. For a rocky planet, two spin conditions are possible, the trapped rotation and the fast rotation, referring to the cases of achieved and non achieved tidal trapping, respectively. We focus on planets whose spin condition is not obvious, because no study is needed for planets which are undoubtedly fast rotators or undoubtedly trapped rotators; moreover, we consider only exoplanets that are interesting from an astrobiological perspective. The current spin conditions of the considered planets are hypothesized, taking into account the age of the host star. Inferences regarding planetary climate and habitability, which is defined by the possibility of stably sustaining the liquid water on the surface, are also discussed. Results of this work show that Kepler62f, Kepler1126c and Kepler1544b are expected to be fast rotators regardless of the orbital eccentricity; the spin condition of Kepler186f, Kepler62e, and Kepler442b cannot be determined without constraints on the eccentricity, which are currently unavailable; Kepler440b is expected to be tidally trapped.
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All authors Salvatore Camposeo, Francesco De Paolis, Vincenzo Orofino, Francesco Strafella, Leonardo Di Venere

Earth and Planetary Astrophysics

Measurements and predictions of H2 pressure-broadening coefficients of CO2 absorption lines for exoplanet atmosphere studies

Faten Hendaoui, Pascale Chelin, Xavier Landsheere et al. (+2 more)

Accurate and comprehensive H2 pressure-induced broadening data for CO2 infrared lines over a wide temperature range are essential for modeling atmospheric opacity of exoplanets. However, available data are currently limited, some of which are affected by large uncertainties. In this work, H2 induced pressure-broadening and pressure-shift coefficients were determined at room temperature for the entire nu3 band of CO2 in the 4.3 micrometer spectral region using a high-resolution Fourier transform spectrometer. In addition, requantized molecular dynamics simulations of the CO2-H2 system were performed using an accurate intermolecular potential. These simulations provide theoretical predictions of H2-broadening coefficients for CO2 lines over a temperature range of 200-1000 K and for rotational quantum number up to J=120. The predicted results show very good agreement with the experimental data, with difference of less than 3%, well below the precision required for exoplanet atmosphere studies. This work provides the first accurate and comprehensive dataset of H2 broadening coefficients for CO2 lines, suitable for modeling of H2-rich exoplanetary atmospheres.
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All authors Faten Hendaoui, Pascale Chelin, Xavier Landsheere, Hassen Aroui, Ha Tran

Instrumentation and Methods for Astrophysics · Cross-listed from math-ph

A self-adjoint Fourier-type model for the iQuad wavefront sensor

Victoria Laidlaw, Olivier Fauvarque, Alfred Miksch et al. (+2 more)

Advanced adaptive optics (AO) systems can use Fourier-type wavefront sensing to correct optical distortions encountered in ground-based telescopes, AO-assisted retinal imaging, and free-space optical communications (FSOC). Recently, a novel Fourier-type wavefront sensor (WFS) known as the iQuad WFS has been introduced. Its design features a focal plane tessellation with a four-quadrant phase mask (FQPM) that incorporates a $\pm \pi/2$ phase shift between adjacent quadrants. In this work, we establish a comprehensive mathematical framework for the iQuad WFS, including its forward models and linearizations based on the Fréchet derivative. We reveal a connection between the iQuad WFS and the 2d finite Hilbert transform and demonstrate that the linear iQuad WFS operator is self-adjoint - a unique property among Fourier-type WFSs. Additionally, we introduce the double iQuad WFS, a two-path configuration that combines two rotated iQuad WFSs. This design addresses the limitations of the single iQuad WFS by suppressing poorly-seen phase components. Moreover, the double setup simplifies the mathematical modeling. We also highlight iQuad similarities to the widely used pyramid wavefront sensor (PWFS). Finally, we extend the concept of modulation to the iQuad WFS, further enhancing its versatility. The theoretical analysis presented here lays the groundwork for the development of fast and robust model-based wavefront reconstruction algorithms for the iQuad WFS, paving the way for future applications in AO instruments.
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All authors Victoria Laidlaw, Olivier Fauvarque, Alfred Miksch, Benoit Neichel, Ronny Ramlau

High Energy Astrophysical Phenomena

A New Timing Signature of Black Hole Spin: Time-Delay Asymmetry in Kerr Accretion Flows

Shakibul Chowdhury

We introduce a new general-relativistic timing observable that measures the breaking of reflection symmetry in photon arrival times caused by black hole spin. Using backward ray tracing in the Kerr spacetime, we construct time-delay maps across the observer image plane and define a mirror-paired asymmetry based on photons arriving from opposite sides of the projected spin axis. In the Schwarzschild limit ($a=0$), the asymmetry vanishes to numerical precision, providing a stringent validation test of the method. For rotating black holes, Kerr rotation breaks the left-right propagation symmetry of null geodesics, producing systematic differences between prograde and retrograde photon trajectories and resulting in a nonzero mirror-paired timing asymmetry, $A_t$. We find that $A_t$ increases with spin and depends strongly on observer inclination and emission radius, with the largest signals arising from emission close to the black hole and from intermediate to high inclinations. Converting the dimensionless asymmetry into physical units yields timing offsets ranging from seconds to hours for representative supermassive black hole systems. Unlike traditional timing analyses based on spatially integrated signals, the observable introduced here isolates directional information encoded in Kerr photon propagation and provides a physically motivated timing signature of black hole rotation. We discuss the implications of this effect for strong-gravity timing studies and X-ray reverberation mapping.
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High Energy Astrophysical Phenomena

Synergy between the Cherenkov Telescope Array Observatory and the Vera C. Rubin Observatory

J. Biteau, J. Hamo, A. Mikhno et al. (+2 more)

The Cherenkov Telescope Array Observatory (CTAO) and the Vera C. Rubin Observatory are set to transform our understanding of the universe over the next decade. These two observatories have multiple areas of complementarity in their scientific applications, ranging from constraints on cosmological parameters to studies of asteroid occultations. The most opportune area of synergy probably lies in the field of time-domain astronomy. Due to their sensitivity and saturation limits, it will be difficult for the two observatories to conduct joint studies of variable and transient sources in the Milky Way. However, they could offer a fresh and rich perspective on non-thermal extragalactic sources, in particular gamma-ray bursts, active galactic nuclei and jetted tidal disruption events. Among these sources lie the best candidates for multi-messenger research into the origin of TeV-PeV neutrinos and multi-EeV cosmic rays. Thus, combined with multi-wavelength observations by X-ray satellites and wide-field gamma-ray instruments, the synergy between Rubin and the CTAO could provide answers to some of the most important questions in astroparticle physics. This scientific potential comes with a challenge: selecting a few alerts from the ten million issued by Rubin each night to repoint the CTAO telescopes. We use the variability of blazars over timescales ranging from a few days to several years as a case study to demonstrate how to address this challenge using the Fink broker of Rubin.
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All authors J. Biteau, J. Hamo, A. Mikhno, J. Peloton, J.-P. Lenain

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

GW240925 and GW250207: Astrophysical Calibration of Gravitational-wave Detectors

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration: A. G. Abac et al. (+1838 more)

GW240925 and GW250207 are two loud gravitational-wave signals from binary black hole coalescences observed with network signal-to-noise ratios $\sim 32$ and $\sim 69$, respectively, by the LIGO Hanford–LIGO Livingston–Virgo network. Gravitational-wave signals from coalescing binaries have characteristic phase and amplitude evolution predicted by general relativity. These signal waveforms, together with measured instrumental calibration uncertainties, are used to infer source parameters. However, for sufficiently loud detections it is possible to constrain the calibration of the detectors directly using the signals themselves. We present the first informative astrophysical measurements of gravitational-wave detector calibration. For GW240925, we verify the inference of Hanford calibration from the astrophysical signal through cross-checks with known calibration errors obtained from in-situ measurements. At the time of GW250207, the Hanford detector was not fully stabilized, leading to elevated calibration uncertainties; thus, astrophysical calibration is essential to obtain accurate data and to enable source localization. These well-localized, high signal-to-noise observations have the potential to offer precise measurements of source properties, stringent tests of general relativity, and informative dark siren measurements, provided that calibration uncertainties are properly incorporated. As detector sensitivity improves, astrophysical calibration will become an increasingly valuable complement to in-situ calibration measurements. Obtaining accurate calibration will be essential for precision gravitational-wave science.
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All authors The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration: A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, A. Adam, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I.-L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi, L. Albers, W. Ali, S. Al-Kershi, C. Alléné, A. Allocca, S. Al-Shammari, P. A. Altin, S. Alvarez-Lopez, W. Amar, O. Amarasinghe, A. Amato, F. Amicucci, C. Amra, C. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Andia, M. Ando, M. Andrés-Carcasona, J. L. Andrey, T. Andrić, J. Anglin, J. Anna, S. Ansoldi, J. M. Antelis, S. Antier, M. Aoumi, E. Z. Appavuravther, S. Appert, S. K. Apple, K. Arai, A. Araya, M. C. Araya, M. Arca Sedda, F. Arciprete, J. S. Areeda, N. Aritomi, F. Armato, S. Armstrong, N. Arnaud, M. Arogeti, S. M. Aronson, K. G. Arun, G. Ashton, Y. Aso, L. Asprea, M. Assiduo, S. Assis de Souza Melo, S. M. Aston, P. Astone, F. Attadio, F. Aubin, K. AultONeal, G. Avallone, E. A. Avila, S. Babak, C. Badger, S. Bae, S. Bagnasco, L. Baiotti, R. Bajpai, T. Baka, K. A. Baker, T. Baker, G. Balbi, G. Baldi, N. Baldicchi, M. Ball, G. Ballardin, S. W. Ballmer, S. Banagiri, B. Banerjee, D. Bankar, T. M. Baptiste, P. Baral, M. Baratti, J. C. Barayoga, K. Baric, B. C. Barish, D. Barker, N. Barman, P. Barneo, F. Barone, B. Barr, M. Barrios, L. Barsotti, M. Barsuglia, D. Barta, M. A. Barton, I. Bartos, A. Basalaev, R. Bassiri, A. Basti, M. Bawaj, P. Baxi, J. C. Bayley, A. C. Baylor, P. A. Baynard II, M. Bazzan, V. M. Bedakihale, F. Beirnaert, M. Bejger, D. Belardinelli, A. S. Bell, C. Bellani, L. Bellizzi, D. Beltran-Martinez, W. Benoit, I. Bentara, M. Ben Yaala, S. Bera, F. Bergamin, B. K. Berger, S. Bernuzzi, M. Beroiz, C. P. L. Berry, I. Berry, D. Bersanetti, T. Bertheas, A. Bertolini, J. Betzwieser, D. Beveridge, G. Bevilacqua, N. Bevins, R. Bhandare, R. Bhatt, A. Bhattacharjee, D. Bhattacharjee, S. Bhattacharyya, S. Bhaumik, V. Biancalana, A. Bianchi, F. Bianchi, I. A. Bilenko, G. Billingsley, A. Binetti, S. Bini, C. Binu, S. Biot, O. Birnholtz, S. Biscoveanu, A. Bisht, M. Bitossi, M.-A. Bizouard, S. Blaber, J. K. Blackburn, L. A. Blagg, C. D. Blair, D. G. Blair, N. Bode, N. Boettner, P. Bogdan, G. Boileau, M. Boldrini, G. N. Bolingbroke, A. Bolliand, L. D. Bonavena, R. Bondarescu, F. Bondu, V. A. Bonhomme, E. Bonilla, M. S. Bonilla, A. Bonino, R. Bonnand, A. Borchers, N. Borghi, V. Boschi, S. Bose, V. Bossilkov, Y. Bothra, A. Boudon, M. Boyle, A. Bozzi, C. Bradaschia, M. J. Brady, P. R. Brady, A. Branch, M. Branchesi, T. Briant, A. Brillet, M. Brinkmann, P. Brockill, E. Brockmueller, A. F. Brooks, B. C. Brown, D. D. Brown, M. L. Brozzetti, S. Brunett, G. Bruno, R. Bruntz, J. Bryant, Y. Bu, F. Bucci, J. Buchanan, O. Bulashenko, T. Bulik, H. J. Bulten, A. Buonanno, K. Burtnyk, R. Buscicchio, D. Buskulic, C. Buy, R. L. Byer, R. Cabrita, V. 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Park, W. Parker, G. Pascale, D. Pascucci, A. Pasqualetti, R. Passaquieti, L. Passenger, D. Passuello, O. Patane, A. V. Patel, D. Pathak, A. Patra, B. Patricelli, B. G. Patterson, K. Paul, S. Paul, E. Payne, T. Pearce, M. Pedraza, A. Pele, F. E. Peña Arellano, X. Peng, Y. Peng, S. Penn, M. D. Penuliar, A. Perego, Z. Pereira, C. Périgois, G. Perna, A. Perreca, J. Perret, S. Perriès, J. W. Perry, S. Peters, S. Petracca, C. Petrillo, H. P. Pfeiffer, H. Pham, K. A. Pham, K. S. Phukon, H. Phurailatpam, M. Piarulli, L. Piccari, O. J. Piccinni, M. Pichot, A. Pied, M. Piendibene, F. Piergiovanni, L. Pierini, G. Pierra, V. Pierro, M. Pietrzak, M. Pillas, L. Pinard, I. M. Pinto, M. Pinto, B. J. Piotrzkowski, M. Pirello, M. D. Pitkin, A. Placidi, E. Placidi, M. L. Planas, W. Plastino, C. Plunkett, R. Poggiani, E. Polini, J. Pomper, L. Pompili, J. Poon, E. Porcelli, A. S. Porter, E. K. Porter, C. Posnansky, R. Poulton, J. Powell, G. S. Prabhu, M. Pracchia, B. K. Pradhan, T. Pradier, A. K. Prajapati, K. Prasai, R. Prasanna, P. Prasia, G. Pratten, A. Praveen, G. Principe, G. A. Prodi, P. Prosperi, P. Prosposito, A. Puecher, J. Pullin, P. Puppo, M. Pürrer, H. Qi, M. Qiao, J. Qin, G. Quéméner, V. Quetschke, P. J. Quinonez, R. Rading, I. Rainho, S. Raja, C. Rajan, B. Rajbhandari, K. E. Ramirez, F. A. Ramis Vidal, M. Ramos Arevalo, A. Ramos-Buades, S. Ranjan, M. Ranjbar, K. Ransom, P. Rapagnani, B. Ratto, A. Ravichandran, A. Ray, V. Raymond, M. Razzano, J. Read, J. Regan, T. Regimbau, T. Reichardt, S. Reid, C. Reissel, D. H. Reitze, A. I. Renzini, B. Revenu, A. Revilla Peña, L. Ricca, F. Ricci, M. Ricci, A. Ricciardone, J. Rice, J. W. Richardson, M. L. Richardson, A. Rijal, K. Riles, H. K. Riley, S. Rinaldi, J. Rittmeyer, C. Robertson, F. Robinet, M. Robinson, A. Rocchi, L. Rolland, J. G. Rollins, A. E. Romano, R. Romano, A. Romero-Rodríguez, I. M. Romero-Shaw, J. H. Romie, S. Ronchini, T. J. Roocke, L. Rosa, T. J. Rosauer, C. A. Rose, D. Rosińska, M. P. Ross, M. Rossello-Sastre, S. Rowan, K. Rowlands, S. K. Roy, S. Roy, D. Rozza, P. Ruggi, N. Ruhama, G. H. Ruiz, E. Ruiz Morales, K. Ruiz-Rocha, V. Russ, S. Sachdev, T. Sadecki, P. Saffarieh, S. Safi-Harb, M. R. Sah, S. Saha, T. Sainrat, S. Sajith Menon, K. Sakai, Y. Sakai, M. Sakellariadou, S. Sakon, O. S. Salafia, F. Salces-Carcoba, L. Salconi, M. Saleem, F. Salemi, M. Sallé, S. U. Salunkhe, S. Salvador, A. Salvarese, A. Samajdar, A. Sanchez, E. J. Sanchez, N. Sanchis-Gual, J. R. Sanders, E. M. Sänger, F. Santoliquido, F. Sarandrea, T. R. Saravanan, N. Sarin, P. Sarkar, A. Sasli, P. Sassi, B. Sassolas, B. S. Sathyaprakash, R. Sato, S. Sato, Yukino Sato, Yu Sato, O. Sauter, R. L. Savage, T. Sawada, H. L. Sawant, S. Sayah, V. Scacco, D. Schaetzl, M. Scheel, A. Schiebelbein, M. G. Schiworski, P. Schmidt, S. Schmidt, R. Schnabel, M. Schneewind, R. M. S. Schofield, K. Schouteden, B. W. Schulte, M. Schulz, B. F. Schutz, E. Schwartz, M. Scialpi, J. Scott, S. M. Scott, R. M. Sedas, T. C. Seetharamu, M. Seglar-Arroyo, Y. Sekiguchi, D. Sellers, N. Sembo, A. S. Sengupta, E. G. Seo, J. W. Seo, V. Sequino, M. Serra, A. Sevrin, T. Shaffer, U. S. Shah, M. A. Shaikh, L. Shao, J. Sharkey, A. K. Sharma, Preeti Sharma, Priyanka Sharma, Ritwik Sharma, Sushant Sharma-Chaudhary, P. Shawhan, N. S. Shcheblanov, E. Sheridan, Z.-H. Shi, R. Shimomura, H. Shinkai, S. Shirke, D. H. Shoemaker, D. M. Shoemaker, R. W. Short, S. ShyamSundar, A. Sider, H. Siegel, V. Sierra, D. Sigg, L. Silenzi, L. Silvestri, M. Simmonds, L. P. Singer, Amitesh Singh, Anika Singh, D. Singh, M. K. Singh, N. Singh, S. Singh, M. R. Sinha, A. M. Sintes, V. Sipala, V. Skliris, B. J. J. Slagmolen, T. J. Slaven-Blair, J. Smetana, D. A. Smith, J. R. Smith, L. Smith, R. J. E. Smith, W. J. Smith, S. Soares de Albuquerque Filho, K. Somiya, I. Song, S. Soni, V. Sordini, F. Sorrentino, H. Sotani, F. Spada, V. Spagnuolo, A. P. Spencer, P. Spinicelli, A. K. Srivastava, F. Stachurski, C. J. Stark, D. A. Steer, N. Steinle, J. Steinlechner, S. Steinlechner, N. Stergioulas, P. Stevens, M. StPierre, M. D. Strong, A. Strunk, A. L. Stuver, M. Suchenek, S. Sudhagar, Y. Sudo, N. Sueltmann, L. Suleiman, K. D. Sullivan, J. Sun, L. Sun, S. Sunil, J. Suresh, B. J. Sutton, P. J. Sutton, K. Suzuki, M. Suzuki, A. Svizzeretto, S. Swain, B. L. Swinkels, A. Syx, M. J. Szczepańczyk, P. Szewczyk, M. Tacca, M. Tagliazucchi, H. Tagoshi, S. C. Tait, K. Takada, H. Takahashi, R. Takahashi, A. Takamori, S. Takano, H. Takeda, K. Takeshita, I. Takimoto Schmiegelow, M. Takou-Ayaoh, C. Talbot, M. Tamaki, N. Tamanini, D. Tanabe, K. Tanaka, S. J. Tanaka, S. Tanioka, D. B. Tanner, W. Tanner, L. Tao, R. D. Tapia, E. N. Tapia San Martín, C. Taranto, A. Taruya, J. D. Tasson, J. G. Tau, A. Tejera, R. Tenorio, H. Themann, A. Theodoropoulos, M. P. Thirugnanasambandam, L. M. Thomas, M. Thomas, P. Thomas, J. E. Thompson, S. R. Thondapu, K. A. Thorne, E. Thrane, J. Tissino, A. Tiwari, Pawan Tiwari, Praveer Tiwari, S. Tiwari, V. Tiwari, E. M. Todd, M. R. Todd, E. Tofani, M. Toffano, A. M. Toivonen, K. Toland, A. E. Tolley, T. Tomaru, V. Tommasini, T. Tomura, H. Tong, C. Tong-Yu, A. Torres-Forné, C. I. Torrie, I. Tosta e Melo, E. Tournefier, M. Trad Nery, A. Trapananti, R. Travaglini, F. Travasso, G. Traylor, M. Trevor, M. C. Tringali, A. Tripathee, G. Troian, A. Trovato, L. Trozzo, R. J. Trudeau, T. Tsang, S. Tsuchida, K. Tsuji, L. Tsukada, K. Turbang, M. Turconi, C. Turski, H. Ubach, A. S. Ubhi, N. Uchikata, T. Uchiyama, R. P. Udall, T. Uehara, K. Ueno, V. Undheim, L. E. Uronen, T. Ushiba, M. Vacatello, H. Vahlbruch, G. Vajente, J. Valencia, M. Valentini, E. Vallejo-Pagès, S. A. Vallejo-Peña, S. Vallero, M. van Dael, E. Van den Bossche, J. F. J. van den Brand, C. Van Den Broeck, M. van der Kolk, M. van der Sluys, A. Van de Walle, J. van Dongen, K. Vandra, M. VanDyke, H. van Haevermaet, J. V. van Heijningen, P. Van Hove, J. Vanier, J. Vanosky, N. van Remortel, M. Vardaro, A. F. Vargas, V. Varma, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, S. Venikoudis, J. Venneberg, R. C. Venterea, P. Verdier, M. Vereecken, D. Verkindt, B. Verma, Y. Verma, S. M. Vermeulen, F. Vetrano, A. Veutro, A. Viceré, S. Vidyant, A. D. Viets, A. Vijaykumar, A. Vilkha, N. Villanueva Espinosa, V. Villa-Ortega, E. T. Vincent, J.-Y. Vinet, S. Viret, S. Vitale, A. Vives, L. Vizmeg, H. Vocca, D. Voigt, E. R. G. von Reis, J. S. A. von Wrangel, W. E. Vossius, L. Vujeva, S. P. Vyatchanin, J. Wack, L. E. Wade, M. Wade, K. J. Wagner, L. Wallace, E. J. Wang, H. Wang, W. H. Wang, Y. F. Wang, Z. Wang, G. Waratkar, R. L. Ward, J. Warner, M. Was, T. Washimi, N. Y. Washington, B. Weaver, S. A. Webster, N. L. Weickhardt, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, K. Wette, C. Wheeler, J. T. Whelan, B. F. Whiting, C. Whittall, E. G. Wickens, D. Wilken, B. M. Williams, D. Williams, M. J. Williams, N. S. Williams, J. L. Willis, B. Willke, M. Wils, L. Wilson, C. W. Winborn, J. Winterflood, C. C. Wipf, G. Woan, J. Woehler, N. E. Wolfe, H. T. Wong, I. C. F. Wong, K. Wong, T. Wouters, J. L. Wright, M. Wright, B. Wu, C. Wu, D. S. Wu, H. Wu, K. Wu, Q. Wu, Z. Wu, E. Wuchner, D. M. Wysocki, V. A. Xu, Y. Xu, N. Yadav, H. Yamamoto, K. Yamamoto, T. S. Yamamoto, T. Yamamoto, R. Yamazaki, T. Yan, H. Yang, K. Z. Yang, Y. Yang, Z. Yarbrough, J. Yebana, S.-W. Yeh, A. B. Yelikar, X. Yin, J. Yokoyama, T. Yokozawa, S. Yuan, H. Yuzurihara, M. Zanolin, M. Zeeshan, T. Zelenova, J.-P. Zendri, M. Zeoli, M. Zerrad, M. Zevin, H. Zhang, L. Zhang, N. Zhang, R. Zhang, T. Zhang, C. Zhao, Yue Zhao, Yuhang Zhao, Z.-C. Zhao, Y. Zheng, H. Zhong, H. Zhou, H. O. Zhu, Z.-H. Zhu, Z. Zhu, A. B. Zimmerman, L. Zimmermann, M. E. Zucker

Solar and Stellar Astrophysics

Starspot activity and surface differential rotation on UX Arietis

Yue Xiang, Shenghong Gu, A. Collier Cameron et al. (+2 more)

We present new Doppler images of the K0 subgiant primary component of the RS CVn-type binary UX Arietis (UX Ari), derived from time-series spectra obtained in November–December of 2017 and 2024. Observations demonstrate that some spectral lines of the K0 IV component exhibit rapid changes on timescales of 1-2 hours, which seem not to be resulting from spot activity, meanwhile other spectral lines show no such fast variations. Through an investigation, we find that the Ca I 6439 $\unicode{x212B}$ profile shows variation that follows the rotational modulation of spots. Using this line as a reference, we derive the least-squares deconvolution (LSD) profile from the selected lines of each spectrum so as to generate a more reliable Doppler image, which is consistent with the shape of the corresponding Ca I 6439 $\unicode{x212B}$ line. The Doppler images are separately reconstructed from the Ca I 6439 $\unicode{x212B}$ and the LSD profiles for each dataset, and the surface maps are in good agreement with each other. All of the surface maps show dominant starspot structure at mid-to-high latitudes with appendages extending to the equator, while their locations differ by about 0.5 in the rotational phase between 2017 and 2024. In 2017 November-December, the main starspot group appears to be spatially associated with a large flare event just half a month later. Through the cross-correlation method, we have derived a weak anti-solar differential rotation for the primary component of UX Ari, while its equator belt is well tidally locked.
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All authors Yue Xiang, Shenghong Gu, A. Collier Cameron, J. R. Barnes, Dongtao Cao

High Energy Astrophysical Phenomena

Evidence for Multiple Orbiting Hotspots in the 340 GHz Variability of Sgr A*

Kazuki Yanagisawa, Tomoharu Oka, Tatsuya Kotani et al. (+3 more)

We analyzed 11 epochs of archival Atacama Large Millimeter/submillimeter Array (ALMA) data to investigate flux density variability of Sgr A* at 340 GHz. In one epoch, the light curve exhibits two short-timescale components with characteristic periods of ~30 min and ~50 min. While the corresponding peaks in the periodogram are highly significant under a white-noise assumption, their significance decreases below 3 \sigma when red-noise variability is taken into account, and we therefore do not regard them as statistically significant periodic detections. Nevertheless, the observed timescales are comparable to the orbital period near the innermost stable circular orbit of Sgr A*, and the light curve shows phase-dependent structure and amplitude evolution consistent with orbital modulation. We find that the variability is well described by a model involving multiple orbiting hotspots with decaying emission. This interpretation suggests that both periodic and non-periodic variability in Sgr A* may arise from a common physical origin in orbiting structures within the accretion flow, providing a unified framework for its millimeter variability.
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All authors Kazuki Yanagisawa, Tomoharu Oka, Tatsuya Kotani, Ryo Ariyama, Kazuki Yanagihara, Yuhei Iwata

Cosmology and Nongalactic Astrophysics

Density-Shear Baryon Acoustic Oscillation as a Cosmological Consistency Check

Kwan Chuen Chan, Yin Li and Jamie McCullough

Tensions often arise between different datasets in cosmology, and consistency tests can serve as a powerful tool for diagnosing potential issues. Density-shear Baryon Acoustic Oscillation (GI BAO) is the imprint of the BAO feature on the shear field induced by the large-scale tidal field. We highlight that GI BAO can provide a robust consistency check for the density BAO, shear measurement, and alignment model. Failure of this check hints at systematics in any of these parts. As an illustration, we present the first GI BAO measurement on photometric data using the Dark Energy Survey Year 3 dataset, achieving a detection significance of $0.86 \sigma$. We find the GI BAO constraint on the BAO scale dilation parameter $\alpha $ to be $ 0.966 \pm 0.252 $ (1$\sigma$), in good agreement with the density BAO constraint, $ 0.966 \pm 0.037 $, thereby validating the density BAO, shear measurement, and the linear alignment model. Furthermore, we argue that combining the density BAO with GI BAO yields results that are more resilient to systematic effects. Thanks to the massive data volumes of stage IV surveys, GI BAO will play an even more prominent role as a consistency check.
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Astrophysics of Galaxies

Metal Enrichment by the First Stars Exploding at the Lower Energy Limit of Pair-Instability Supernovae

Aron Kordt, Simon C. O. Glover and Ralf S. Klessen

The first generation of stars, Population III (Pop III), is believed to be massive, with some potentially having masses in the range 140 M$_\odot$ to 270 M$_\odot$ and capable of exploding as a pair-instability supernova (PISN). Such events release large amounts of energy and produce substantial quantities of metals, suggesting that they should leave characteristic signatures in the abundance patterns of extremely metal-poor (EMP) stars observed in the local Universe. No clear imprint of PISNe is seen in the local EMP star population, implying either that these events were rare or that stars forming from PISN-enriched gas had metallicities too high to find them in the EMP population. Previous work explored the latter possibility by investigating the enrichment by PISNe with masses and explosion energies at the upper end of the theoretical range (270 M$_\odot$, $10^{53}$ erg). Here, we complement that work at the opposite extreme: Pop III stars at the lower mass (140 M$_\odot$) and explosion energy ($5\cdot 10^{51}$ erg) limit. Using a cosmological hydrodynamic simulation, we self-consistently track the formation of Pop III stars, their radiative and mechanical feedback, and the subsequent formation of second-generation stars in metal-enriched gas. We find that all second-generation stars are exclusively internally enriched by their progenitor within the same halo, thereby imprinting the abundance pattern of a single first-generation star. The median [Fe/H] abundance of second-generation stars is ~ -5.5 which is 2.9 dex smaller than in the high-energy PISN case. Our results demonstrate that if Pop III PISNe were common, we would expect to find stars with the characteristic odd-even abundance pattern produced by PISNe within the observed EMP population. Their absence in observations therefore strongly disfavours PISNe as the dominant channel of early metal enrichment.
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High Energy Astrophysical Phenomena

Interacting Binary Stars as Progenitors for Interacting Supernovae

Sung-Han Tsai, Ke-Jung Chen, Keiichi Maeda et al. (+2 more)

Dense, compact circumstellar media (CSM) are required to power strongly interacting supernovae, yet their physical origin remains uncertain. We present a systematic study of binary stellar evolution models computed with MESA, demonstrating that Case C mass transfer, initiated after core helium ignition, can naturally produces the dense, nearby CSM inferred in interacting events. Across a grid of binary models, we find that donors of 10–20 solar masses in binaries with separations of approximately 1000–2700 solar radius undergo late-stage Roche-lobe overflow within ~10^3 yr prior to core collapse, ejecting ~0.01–0.2 solar masses and forming CSM extending to ~10^16–10^18 cm. Our results suggest that the Case C mass transfer may account for ~13% of all core-collapse supernova (CCSN) progenitors, rather than representing a rare channel. A subset of these Case C binaries produces CSM properties that are quantitatively in agreement with those inferred for interacting supernovae such as SN 2014C. In contrast to earlier binary interactions or single-star mass loss, Case C transfer operates at the right time and scale to shape the immediate pre-supernova environment without requiring ad hoc eruptive mechanisms. Our results identify late-stage binary interaction as a robust and physically motivated channel for producing the dense CSM that powers interacting supernovae.
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All authors Sung-Han Tsai, Ke-Jung Chen, Keiichi Maeda, Po-Sheng Ou, Friedrich K. Röpke

Cosmology and Nongalactic Astrophysics

A Reusable Hierarchical Framework for Joint Inference of Ultralight-Dark-Matter Mass and Core-Halo Scaling

Prasun Panthi and Md Shahrier Islam Arham

Ultralight-dark-matter rotation-curve analyses often infer the particle mass after fixing a relation between the central soliton and its host halo. The resulting mass constraint is then conditional on a population-level relation that the data may not independently support. We present a reusable hierarchical Bayesian framework that instead infers the ultralight particle mass and the core-halo scaling exponent jointly from a galaxy population. The differentiable forward model combines a Schive-normalized soliton with a smoothly matched, regularized NFW envelope and allows galaxy-level halo and stellar parameters to be inferred together with the global dark-matter parameters. We apply the framework to 106 SPARC galaxies, including 26 systems with bulges, and sample the resulting 346-dimensional posterior with JAX/NumPyro NUTS. The free-scaling run has zero divergences and $\hat{R}\simeq 1.000$ for the global parameters. The posterior moves to the high-mass, weak-scaling boundary, with $\log_{10}(m_\phi/\mathrm{eV})=-19.20^{+0.12}_{-0.11}$ and $\alpha=0.014^{+0.023}_{-0.011}$. In this regime, the solitonic cores lie below the radial scales probed by the rotation curves, while the baryonic terms and outer NFW envelope carry the visible fits. The same boundary behaviour remains after removing UGC06787 and after widening the high-mass stellar-to-halo-mass prior. The selected SPARC sample therefore does not give an interior joint constraint on the particle mass and core-halo scaling relation within the adopted model. The framework makes this unresolved-core limit explicit instead of interpreting the prior boundary as an interior mass constraint. Its modular structure also allows the same analysis to be applied to synthetic recovery tests, expanded or higher-resolution rotation-curve samples, and alternative halo models.
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High Energy Astrophysical Phenomena

Are Single-Zone Emission models Sufficient to Explain GRB 220426A and GRB 230812B?

Soumya Gupta, Sunder Sahayanathan, Saharsh Shanu et al. (+1 more)

Gamma-ray bursts (GRBs) are the universe's most energetic phenomena (isotropic luminosity $\sim 10^{51} - 10^{54}$ ergs/s) lasting for a very short duration ($\sim$ milliseconds - a few seconds). Even after an average of one GRB detected per day, their emission mechanism remains contentious. Inferences drawn from the empirical modelling of the GRB spectrum are often inconclusive. Some studies favor the emission from a thermal blast of hot plasma, while others suggest a synchrotron emission originating from a rapid acceleration of particles at the expense of the burst energy. Under these scenarios, the spectral width of the burst ($\mathcal{W}$), which is measured at half maxima, is expected to decrease with time. We show that for the GRB 220426A and GRB 230812B, $\mathcal{W}$ increases with time, raising serious concerns regarding the validity of these emission models. The results instead offer strong evidence that the GRB prompt phase involves the development of multiple emission zones, whose relative contributions change over time.
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All authors Soumya Gupta, Sunder Sahayanathan, Saharsh Shanu, Rishabh Nath

High Energy Astrophysical Phenomena

Black Hole Ringdown Seen in Photon Polarization Swings

Jiewei Huang, Yehui Hou, Zhen Zhong et al. (+2 more)

Light propagating through a perturbed spacetime could imprint the underlying gravitational waveform directly onto electromagnetic observables. In this Letter, we develop a covariant perturbative framework for polarized photon propagation in generic curved spacetimes, and derive a compact expression for the observable polarization-angle (PA) swing during Kerr ringdown, explicitly demonstrating its time-domain locking to the quasi-normal modes. We confirm this behavior using dynamical ray-tracing calculations for a broad class of photon trajectories. Photons grazing the strong-field region exhibit an achromatic, damped PA oscillation that tracks the ringdown, with a phase set by the mode's angular structure. The swing amplitude can reach $\sim 10^{\circ}$ and leaves distinctive signatures in spatially resolved autocorrelations. These results open a new polarimetric window onto black hole mergers and ringdown.
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All authors Jiewei Huang, Yehui Hou, Zhen Zhong, Minyong Guo, Bin Chen

Earth and Planetary Astrophysics

A Hybrid Origin for the Multiple Ring-Gap Structures in the Large Protoplanetary Disk V1094 Sco: A Low-Mass Planet and Secular Gravitational Instability

Masayuki Yamaguchi, Masahiro N. Machida, Ryosuke T. Tominaga et al. (+7 more)

High spatial resolution observations reveal that some protoplanetary disks host multiple ring-gap pairs at large stellocentric radii, yet their physical origin remains unsettled. We present a multi-wavelength analysis of the V1094~Sco disk using Atacama Large Millimeter/submillimeter Array Band~6 continuum and $^{12}$CO and $^{13}$CO $J=2-1$ emission, together with a Very Large Telescope/SPHERE near-infrared scattered light image. The continuum image shows four narrow dust ring-gap pairs extending to exceptionally large radii ($r \sim 380$ au), while the CO isotopologues trace a spatially extended gas disk ($r \sim 760$ au) in Keplerian rotation. From the dust ring widths, we place conservative upper limits on the turbulent viscosity parameter, $\alpha \lesssim 10^{-3}$ and potentially $\lesssim 10^{-4}$, implying weak turbulence. The ensemble of gap widths and depths is inconsistent with a simple one-planet-per-gap interpretation. At $r \simeq 100$~au, a double gap and its scattered light counterpart are consistent with multi-gap excitation by a single low-mass companion of $(55 \pm 35)\,M_{\oplus}$. At $r \simeq 170$-$230$~au, the outer ring system shows regular spacing and no clear scattered light counterpart, indicating mechanisms that operate primarily at the disk midplane. These outer rings are quantitatively compatible with secular gravitational instability. V1094~Sco therefore supports a hybrid pathway in which weak turbulence in an extended disk allows secular gravitational instability to assemble long-lived midplane dust concentrations that can cradle planet formation beyond $\sim100$~au, alongside planet-driven substructures at intermediate radii.
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All authors Masayuki Yamaguchi, Masahiro N. Machida, Ryosuke T. Tominaga, Jinshi Sai, Takayuki Muto, Michihiro Takami, Hauyu Baobab Liu, Ayumu Shoshi, Takashi Tsukagoshi, Shu Ishibashi

Cosmology and Nongalactic Astrophysics

Secondary-Mass Features improve Spectral-Siren $H_0$ Constraints

Yin-Jie Li, Yi-Ying Wang, Yuan-Zhu Wang et al. (+2 more)

Gravitational-wave (GW) signals from compact binary coalescences (CBCs) enable independent measurements of the Hubble constant \(H_0\) via the spectral siren method, which critically depends on an accurate model of the source-frame mass distribution. While the primary mass function has been extensively studied, the impact of the secondary mass distribution on cosmological inference has been largely overlooked. Here, we perform a joint inference of population and cosmological parameters using 142 confident CBC detections from GWTC-4.0, adopting a new parametric model that flexibly describes features in both the component-mass spectrum and the pairing function, with particular emphasis on the secondary masses. We find \(H_0 = 71.4^{+13.8}_{-13.4} \;\mathrm{km\,s^{-1}\,Mpc^{-1}}\) (68% CL) from spectral sirens alone, and \(H_0 = 73.5^{+9.2}_{-7.2} \;\mathrm{km\,s^{-1}\,Mpc^{-1}}\) when combined with the bright siren GW170817. Compared to the standard LVK Fullpop-4.0 analysis, these constraints represent improvements of \(\sim29.8\%\) and \(\sim22.2\%\) in \(H_0\) uncertainty, respectively. The enhanced precision is driven by previously unmodeled features, including peaks near \(18\,M_\odot\) and \(65\,M_\odot\) as well as mass-dependent pairing transitions at \(28\,M_\odot\) and \(52\,M_\odot\). Our results demonstrate that the secondary mass function is also a key ingredient for precision standard siren cosmology.
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All authors Yin-Jie Li, Yi-Ying Wang, Yuan-Zhu Wang, Shao-Peng Tang, Yi-Zhong Fan

High Energy Astrophysical Phenomena

A narrow Comptonization locus in Seyfert slab coronae: implications for dominant coronal dissipation and reduced feedback

Haichao Xu

The thermal state of active galactic nucleus (AGN) coronae is commonly described by the electron temperature $kT_{\rm e}$, the Thomson optical depth $\tau_{\rm T}$, and the geometry of the Comptonizing medium. We compile a literature sample of radio-quiet Seyfert galaxies with direct slab-geometry thermal Comptonization measurements of $kT_{\rm e}$ and $\tau_{\rm T}$. For bottom-illuminated slab coronae, we adopt a geometry-motivated effective Comptonization parameter, $y=4\theta\tau_{\rm T}\,{K_3(1/\theta)} / {K_2(1/\theta)}$, where $\theta=kT_{\rm e}/m_{\rm e}c^2$ and $K_n$ is the modified Bessel function of the second kind. We find that the compiled slab-corona measurements are distributed along a narrow anti-correlated ridge in the $kT_{\rm e}-\tau_{\rm T}$ plane. For the cleaned primary compTT sample, this ridge corresponds to $\langle y\rangle=0.770$ with a logarithmic dispersion of only 0.086 dex. We then compare the observed ridge with reduced-feedback slab-equilibrium calculations and find that the locus favours a corona-dominated local energy budget, $f\simeq1$, together with a feedback factor well below the full-covering value, $g\ll1$. We interpret the constant-$y$ locus as implications for dominant local coronal dissipation and reduced disc-corona radiative feedback, consistent with a patchy corona. Supplementary pair-balance calculations indicate that the low-temperature, high-optical-depth part of the sample is unlikely to be sustained by a purely thermal pair plasma alone, suggesting that the fitted optical depths are more plausibly dominated by electron–ion plasma.
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