Instrumentation and Methods for Astrophysics
Reconstruction of Energy of Ultra-High-Energy Cosmic Rays Registered with a Fluorescence Telescope: One Time Frame Might Be Enough
Mikhail Zotov and Andrei Trusov
We address the challenge of reconstructing the energy of three ultra-high-energy
cosmic rays registered with a small fluorescence
telescope EUSO-TA that operated in 2015 at the site of the
Telescope Array experiment in Utah, USA. Each of these events was recorded within one time frame. Conventional methods of energy reconstruction are not applicable in this case because the events do not have light curves but a single data point. As an alternative, we consider a number of approaches based on artificial neural networks. We demonstrate that a signal recorded by a fluorescence
telescope within one time frame might be enough to reconstruct the energy of a primary particle with reasonable accuracy using an ensemble of simple convolutional neural networks. Contrary to the conventional approach, reconstruction of the shower geometry is not needed for this. More than this, preliminary estimates can be obtained even without recognizing the shower track. However, there remain some problems that do not allow us to claim that the suggested method is universal and always works. We discuss difficulties that we faced and possible ways of improving the method.
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Astrophysics of Galaxies
Black Holes in the Shadow: The Missing High-Ionization Lines in the Earliest JWST AGNs
Greta Zucchi, Xihan Ji, Piero Madau et al. (+5 more)
Observations with the James Webb Space
Telescope (JWST) have uncovered a substantial population of high-
redshift, broad-line active
galactic nuclei (AGNs), whose properties challenge standard models of black hole growth and AGN emission. We analyze a spectroscopic sample of 34 Type 1 AGNs from the JWST Advanced Deep Survey (JADES) survey, spanning
redshifts 1.7 < z < 9, to constrain the physical nature of the
accretion flows powering these sources with broad-line diagnostics statistically for the first time. At z > 5, we find a marked suppression of high-ionization emission lines (HeII, CIV, NV) relative to prominent broad Halpha and narrow [OIII] features. This contrast places strong constraints on the shape of the ionizing spectral energy distribution (SED) and on the physical conditions in the broad-line region (BLR). By comparing the observations to photoionization models based on SEDs of black holes accreting at sub-Eddington ratios, we show that standard AGN continua struggle to reproduce the observed broad line ratios and equivalent widths across a wide ionization parameter range. These results suggest the need for modified SEDs – either intrinsically softened due to super-Eddington
accretion or radiative inefficiencies in the innermost disk, or externally filtered by intervening optically thick gas that absorbs or scatters the highest-energy
photons before they reach the BLR.
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All authors Greta Zucchi, Xihan Ji, Piero Madau, Roberto Maiolino, Ignas Juodžbalis, Francesco D'Eugenio, Sophia Geris, Yuki Isobe
Cosmology and Nongalactic Astrophysics
First galaxy ultraviolet luminosity function limits on dark matter-proton scattering
Hovav Lazare, Ely D. Kovetz, Kimberly K. Boddy et al. (+1 more)
Scattering between dark matter (DM) and
protons leads to suppressed small-scale fluctuations, with implications for a variety of cosmological observables. In this work, we search for evidence of DM-
proton scattering with an interaction cross section $\sigma\!=\!\sigma_0 (\frac{v}{c})^n$ for $n=0,2$ and $4$, corresponding e.g. to velocity-independent contact interactions from heavy mediators, velocity-dependent pseudoscalar-mediated scattering, and higher-order dipole interactions, respectively, using high-
redshift ($z \sim4-10$) ultraviolet
galaxy luminosity functions (UVLFs) observed by Hubble Space
Telescope (HST). We employ an adjusted implementation of GALLUMI combined with the modified Boltzmann solver CLASS DMeff that accounts for interacting DM, and incorporate UVLF data from both blank and lensed HST fields, alongside Planck CMB data and the Pantheon
supernova catalog in a
Bayesian analysis framework to set constraints on $\sigma_0$. Our results show that including lensed UVLF data, which probe fainter
galaxies than the blank HST fields and thus smaller scales, leads to a substantial improvement in the constraints on $\sigma_0$ for $n>0$, surpassing existing bounds from Milky-Way (MW) satellite abundance and CMB anisotropies. For $m_{\chi} = 1\,\rm MeV $, for example, we set the upper bounds at $1.1\times 10^{-25} \, \rm cm^2$ for $n=2$ and $2.1\times 10^{-22} \, \rm cm^2$ for $n=4$. For $n=0$, our bound is within an order of magnitude of those from the Lyman-$\alpha$ forest and MW satellites.
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All authors Hovav Lazare, Ely D. Kovetz, Kimberly K. Boddy, Julian B. Munoz
Astrophysics of Galaxies
The JWST-NIRCam View of Sagittarius C. III. The Extinction Curve
Lucía Bravo Ferres, Francisco Nogueras-Lara, Rainer Schödel et al. (+8 more)
Determining the infrared extinction curve towards the
Galactic centre is crucial for accurately correcting observed data and deriving the underlying
stellar populations. However, extinction curves reported in the literature often show discrepancies. We aim to derive the infrared extinction curve towards the
Galactic centre based on JWST-NIRCam data for the first time, using observations of the Sagittarius C region in the 1-5 $\mu$m range. We determined extinction ratios using two different methods, both based on measuring the reddening vector using the slope of red clump
stars, whose intrinsic properties are well known, in observed colour-magnitude diagrams. The extinction curve derived in this work is in good agreement with previous results in the literature. We obtained the following extinction ratios relative to F162M: $A_\mathrm{F115W} : A_\mathrm{F162M} : A_\mathrm{F182M} : A_\mathrm{F212N} : A_\mathrm{F360M} : A_\mathrm{F405N} : A_\mathrm{F470N} : A_\mathrm{F480M} = 1.84 \pm 0.03 : 1.00 : 0.789 \pm 0.005 : 0.607 \pm 0.014 : 0.306 \pm 0.011 : 0.248 \pm 0.017 : 0.240 \pm 0.019 : 0.21 \pm 0.03$. Besides, we found different values of the extinction index for the short- ($\lambda \sim 1-2.5\,\mu$m, $\alpha \sim 2$) and long-wavelength ($\lambda \sim 2.5-5\,\mu$m, $\alpha \sim 1.4$) regimes, with the extinction curve flattening at longer wavelengths. Comparison with extinction curves derived both inside and outside the
Galactic centre suggests that the infrared extinction curve does not significantly vary in the central regions, and shows no significant evidence for variations between different lines of sight beyond the inner
Galaxy within the uncertainties.
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All authors Lucía Bravo Ferres, Francisco Nogueras-Lara, Rainer Schödel, Rubén Fedriani, Adam Ginsburg, Samuel Crowe, Jonathan C. Tan, Morten Andersen, Joseph Armstrong, Yu Cheng, Zhi-Yun Li
High Energy Astrophysical Phenomena
State-Dependent X-ray Variability in Cygnus X-1: A 12-Year NuSTAR Timing Study of Accretion Flow Geometry
Kshitij Duraphe, Kartik Mandar, Chooda Khanal et al. (+6 more)
We present a comprehensive timing analysis of the black hole X-ray binary Cygnus X-1 using 26 NuSTAR observations spanning 2012-2024, providing the most detailed characterization to date of its
accretion flow variability across spectral states. Our analysis reveals fundamental insights into the physics governing state transitions in
stellar-mass black holes. We discover distinct bimodal flux distributions in the 8-79 keV band with well-separated peaks, contrasting with overlapping distributions in the 3-8 keV band. This energy-dependent bimodality establishes hard X-rays as the optimal diagnostic for state classification, directly tracing the
geometric transformation between corona-dominated and disk-dominated configurations. Power spectral analysis uncovers state-dependent characteristic frequencies shifting from 0.050 Hz (hard) to 0.074 Hz (intermediate), with featureless red noise in soft states. These frequencies correspond to disk truncation radii evolving from $\sim$5.5 $R_g$ to $\sim$2 $R_g$, providing direct observational evidence for the inward progression of the
accretion disk during state transitions. Frequency-dependent time lags evolve systematically from $\sim$50 ms hard lags at 0.1 Hz in hard states to near-zero in soft states, quantifying the collapse of the Comptonizing corona. Linear rms-flux relations persist across all states with parameters that precisely track the relative contributions of thermal versus non-thermal emission components. Most remarkably, we identify a failed state transition (observation 30302019006) exhibiting anticorrelated band behavior, suppressed variability ($F_{var}$ < 1.38%), and apparent sub-ISCO truncation. This discovery challenges standard transition models and suggests new pathways for
accretion flow
evolution in wind-fed systems.
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All authors Kshitij Duraphe, Kartik Mandar, Chooda Khanal, Abha Pareek, Tejaswi Kondhiya, V Sree Suswara, Deeksha Dinesh, Vidyasagar Bhat, Gopal Bhatta
Cosmology and Nongalactic Astrophysics
Selecting Clusters and Protoclusters via Stellar Mass Density: II. Application to HSC-SSP Observations
Marcelo C. Vicentin, Laerte Sodré Jr., Michael A. Strauss et al. (+2 more)
We present a selection of candidates of clusters and protoclusters of
galaxies identified in the photometric data of the HSC-SSP Wide Public Data Release 3 (PDR3), spanning the
redshift range $\rm 0.1 \leq z \leq 2$. The selection method, detailed in Vicentin et al. (2025), involves detecting massive
galaxies located in high-density regions of matter, identified as potential central dominant
galaxies, i.e., (proto)BCGs. Probabilistic criteria based on proximity to the candidate central
galaxy and the expected
stellar mass of member
galaxies are applied to identify likely members of each structure. We produced updated photometric
redshift estimates using deep learning methods trained on a
dataset combining spectroscopic
redshifts from the HSC-SSP Wide PDR3, high-accuracy photometric
redshifts from the COSMOS2020 catalog, and mid-infrared data from the unWISE catalog for matched sources. Our method achieves a predicted purity of $\sim 90\%$ in detecting (proto)clusters, with $\gtrsim 65\%$ correctly identifying the (proto)BCG. A total of 16,007 candidate (proto)clusters were identified over an effective area of $\rm \sim 850 \ deg^{2}$ within the HSC-SSP Wide footprint. Comparisons with other existing catalogs reveal a good level of consistency, while also highlighting that different methods yield complementary discoveries. We further compare richness and
halo masses from our optical catalog with those from recent X-ray cluster catalogs (eROSITA and MCXC-II), finding a moderate positive correlation and a scatter of $\rm \sim 0.4$ dex. This catalog provides a valuable new set of targets for the
Prime Focus Spectrograph (PFS) instrument.
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All authors Marcelo C. Vicentin, Laerte Sodré Jr., Michael A. Strauss, Erik V. R. de Lima, Pablo Araya-Araya
Cosmology and Nongalactic Astrophysics
Selecting Clusters and Protoclusters via Stellar Mass Density: I. Method and tests on Mock HSC-SSP catalogs
Marcelo C. Vicentin, Pablo Araya-Araya, Laerte Sodré Jr. et al. (+1 more)
We present an
algorithm designed to identify
galaxy (proto)clusters in wide-area photometric surveys by first selecting their dominant
galaxy-i.e., the Brightest Cluster
Galaxy (BCG) or protoBCG-through the local
stellar mass density traced by massive
galaxies. We focus on its application to the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) Wide Survey to detect candidates up to $\rm z \sim 2$. In this work, we apply the method to mock
galaxy catalogs that replicate the observational constraints of the HSC-SSP Wide Survey. We derive functions that describe the probability of a massive
galaxy being the dominant
galaxy in a structure as a function of its
stellar mass density contrast within a given
redshift interval. We show that
galaxies with probabilities greater than 50% yield a sample of BCGs/protoBCGs with $\gtrsim 65\%$ purity, where most of the contamination arises from
galaxies in massive groups below our cluster threshold. Using the same threshold, the resulting (proto)cluster sample achieves 80% purity and 50% completeness for
halos with $M_{\rm{halo}} \geq 10^{14} \ M_{\odot}$, reaching nearly 100% completeness for $M_{\rm{halo}} \geq 10^{14.5} \ M_{\odot}$. We also assign probabilistic membership to surrounding
galaxies based on
stellar mass and distance to the dominant
galaxy, from which we define the cluster richness as the number of
galaxies more likely to be true members than contaminants. This allows us to derive a
halo mass-richness relation. In a companion paper, we apply the
algorithm to the HSC-SSP data and compare our catalog with others based on different cluster-finding techniques and X-ray detections.
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All authors Marcelo C. Vicentin, Pablo Araya-Araya, Laerte Sodré Jr., Michael A. Strauss
Instrumentation and Methods for Astrophysics
Deep Learning in Astrophysics
Yuan-Sen Ting
Deep learning has generated diverse perspectives in astronomy, with ongoing discussions between proponents and skeptics motivating this review. We examine how neural networks complement classical statistics, extending our data analytical toolkit for modern surveys. Astronomy offers unique opportunities through encoding physical
symmetries, conservation laws, and differential equations directly into architectures, creating models that generalize beyond training data. Yet challenges persist as unlabeled observations number in billions while confirmed examples with known properties remain scarce and expensive. This review demonstrates how deep learning incorporates domain knowledge through architectural design, with built-in assumptions guiding models toward physically meaningful solutions. We evaluate where these methods offer genuine advances versus claims requiring careful scrutiny. - Neural architectures overcome bias-variance trade-offs among scalability, expressivity, and data efficiency by encoding physical
symmetries and conservation laws into network structure, enabling learning from limited labeled data. - Simulation-based inference and anomaly detection extract information from complex, non-Gaussian distributions where analytical likelihoods fail, enabling field-level cosmological analysis and systematic discovery of rare phenomena. - Multiscale neural modeling bridges resolution gaps in astronomical simulations, learning effective subgrid physics from expensive high-fidelity runs to enhance large-volume calculations where direct computation remains prohibitive. - Emerging paradigms-reinforcement learning for
telescope operations, foundation models learning from minimal examples, and large
language model
agents for research automation-show promise though are still developing in astronomical applications.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Naoya Kitajima and Michiru Uwabo-Niibo
We show that
axions can be produced from Abelian-
Higgs cosmic strings due to the
axion-gauge coupling. The strong
magnetic field is confined in the string, and the electric field is induced around the moving string, allowing
axion productions from the dynamics of
cosmic strings. Our numerical analysis on the string collision shows that a sizable number of
axions can be produced at the reconnection, and further emissions occur from moving kinks afterward. Large-scale
lattice simulations of the string network further reveal
multimodal axion emissions in the sense that
axions are produced in both the low-energy and high-energy regimes. The former can contribute to the cold dark matter and the latter can be regarded as dark radiation. We found that the
axion with GeV or heavier mass can explain the current relic dark matter abundance and simultaneously predicts a sizable amount of dark radiation which can be probed by future observations.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Big Bang Nucleosynthesis constraints on space-time noncommutativity
Teodora Maria Matei, Cristian Croitoru and Tiberiu Harko
We consider the implications of the modified dispersion relations, due to the noncommutativity of the spacetime, for a
photon gas filling the early Universe in the framework of the Big Bang Nucleosynthesis (BBN) processes, during the period of light elements formation. We consider three types of deformations present in the dispersion relations for the radiation gas, from which we obtain the low temperature corrections to the energy density and pressure. The cosmological implications of the modified equations of state in the BBN era are explored in detail for all radiation models. The effects induced on the nucleosynthesis process by spacetime noncommutativity are investigated by evaluating the abundances of relic
nuclei (Hydrogen, Deuterium, Helium-3, Helium-4, and Lithium-7). The
primordial mass fraction estimates and their deviations due to changes in the freezing temperature impose an upper limit on the energy density of the deformed
photon gas, which follows from the modified Friedmann equations. The deviations from the standard energy density of the radiative
plasma are therefore constrained by the abundances of the Helium-4
nuclei. Upper limits on the free parameters of the spacetime noncommutativity are obtained via a numerical analysis performed using the PRyMordial software package. The
primordial abundances of the light elements are obtained by evaluating the thermonuclear reaction rates for the considered noncommutative spacetime models. An MCMC (Markov Chain Monte Carlo) analysis allows to obtain restrictions on the free parameters of the modified dispersion relations. The numerical and statistical approach is implemented in the python code PRyNCe, available on GitHub.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Scattering of non-relativistic finite-size particles and puffy dark matter direct detection
Wu-Long Xu, Jin Min Yang and Jun Zhao
In this work we consider the scattering between non-relativistic particles with different finite sizes. We first calculate their interaction potential and apply the partial wave method to obtain their scattering cross section. Our findings show that the particle size can significantly affect the scattering between non-relativistic particles. Then we apply such a study to direct detection of puffy dark matter. We find that the finite size of the target
nucleus may introduce non-perturbative effects that differ from the scenario of point-like dark matter. For large-size dark matter particles, this non-perturbative regime in the dark matter
nucleus scattering cross section effectively disappears; while for small values of the size-to-range ratio in the scattering process, a significant non-perturbative regime can maintain. Finally, for the direct detection of nugget-type puffy dark matter with a small number of constituent particles, we find that the stability conditions for the formation of bound-state dark matter can provide constraints on the dark matter
nucleus scattering cross section.
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Astrophysics of Galaxies
The Green Bank Ammonia Survey: Data Release 2
Jaime E. Pineda, Rachel K. Friesen, Erik Rosolowsky et al. (+22 more)
We present an overview of the final data release (DR2) from the Green Bank Ammonia Survey (GAS). GAS is a Large Program at the Green Bank
Telescope to map all Gould Belt
star-forming regions with $A_\mathrm{V} \gtrsim 7$~mag visible from the northern hemisphere in emission from NH$_3$ and other key molecular tracers. This final release includes the data for all the regions observed: Heiles Cloud 2 and B18 in Taurus; Barnard 1, Barnard 1-E, IC348, NGC 1333, L1448, L1451, and Per7/34 in Perseus; L1688 and L1689 in Ophiuchus; Orion A (North and South) and Orion B in Orion; Cepheus, B59 in Pipe; Corona Australis (CrA) East and West; IC5146; and Serpens Aquila and MWC297 in Serpens. Similar to what was presented in GAS DR1, we find that the NH$_3$ emission and
dust continuum emission from Herschel correspond closely. We find that the NH$_3$ emission is generally extended beyond the typical 0.1 pc length scales of dense cores, and we find that the transition between coherent core and turbulent cloud is a common result. This shows that the regions of coherence are common throughout different
star forming regions, with a substantial fraction of the high column density regions displaying subsonic non-thermal velocity dispersions. We produce maps of the gas kinematics, temperature, and NH$_3$ column densities through forward modeling of the hyperfine structure of the NH$_3$ (1,1) and (2,2) lines. We show that the NH$_3$ velocity dispersion, $\sigma_v$, and gas kinetic temperature, $T_{\rm kin}$, vary systematically between the regions included in this release, with an increase in both the mean value and spread of $\sigma_v$ and $T_{\rm kin}$ with increasing
star formation activity. The data presented in this paper are publicly available via \dataset[DOI: 10.11570/24.0091]{https://doi.org/10.11570/24.0091}.
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All authors Jaime E. Pineda, Rachel K. Friesen, Erik Rosolowsky, Ana Chacón-Tanarro, Michael Chun-Yuan Chen, James Di Francesco, Helen Kirk, Anna Punanova, Youngmin Seo, Yancy Shirley, Adam Ginsburg, Stella S. R. Offner, Ayush Pandhi, Ayushi Singh, Feiyu Quan, Héctor G. Arce, Paola Caselli, Spandan Choudhury, Alyssa A. Goodman, Fabian Heitsch, Peter G. Martin, Christopher D. Matzner, Philip C. Myers, Elena Redaelli, Samantha Scibelli
High Energy Astrophysical Phenomena
Coherence of Supermassive Black Hole Binary Demographics with the nHz Stochastic Gravitational Wave Background
Katsunori Kusakabe, Yoshiyuki Inoue and Daisuke Toyouchi
We present a refined estimation of the
stochastic gravitational wave background (SGWB) based on observed dual active
galactic nuclei (AGNs) together with AGN X-ray luminosity functions, in light of recent
Pulsar Timing Array detections of an nHz SGWB. We identify a characteristic luminosity dependence in dual AGN fractions by compiling recent observational
datasets, providing crucial constraints on supermassive black hole binary (SMBHB) populations. Our AGN-based model reproduces the current SGWB measurements within PTA observational uncertainties of $2 - 4 \sigma$ uncertainties, demonstrating consistency between electromagnetic and gravitational wave observations. These findings establish SMBHBs as the dominant source of the nHz gravitational wave signal, providing crucial insights into their demographics and
evolution.
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High Energy Astrophysical Phenomena
Investigation for binary characteristics of LS I+61303 with optical polarization
Jiaxin Liu, Haoyu Yuan, Xiangli Lei et al. (+3 more)
We investigate the optical linear polarization caused by Thomson scattering of the
stellar radiation for gamma-ray binary \lsi61, which likely contains a young
pulsar. Based on the
pulsar binary scenario, we model the interaction between the
pulsar wind and
stellar wind from the massive companion
star, which creates a shock. To accurately compute the resulting polarization of the
stellar wind, we develop a method for the Thomson scattering that accounts for the finite size of the companion
star. By fitting the optical polarization data, we constrain the system parameters, such as eccentricity, the momentum ratio of the two winds, and mass-loss rate from the companion
star. We find that (i) the predicted eccentricity $e\sim 0.1$ is smaller than the values derived from the radial velocity curve and (ii) the orbital phase of the periastron is $\nu_{\rm p}=0.5-0.6$, which is consistent with the previous polarization study of Kravtsov et al. Additionally, we estimate the mass-loss rate from the companion
star and the momentum ratio of two winds as $\dot{M}\sim 2\times 10^{-6}\rm M_{\odot}~{\rm year^{-1}}$ and $\eta>0.1$, respectively. Assuming that the
pulsar wind carries the
spin-down energy, the
spin-down
magnetic field of the putative
pulsar inferred from these parameters is of the order of $B\sim 10^{14}\mathrm{G}$, which may support the highly-B
pulsar or magnetar scenario for the compact object of $\rm{LS\ I} +61^{\circ}303$. We also discuss the dispersion measure under the predicted orbital geometry and provide a corresponding interpretation of the pulsed
radio signal detected by FAST.
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All authors Jiaxin Liu, Haoyu Yuan, Xiangli Lei, Wenlong Xu, Jumpei Takata, Weihua Lei
High Energy Astrophysical Phenomena
Characterizing IceTop Response to Low-Energy Air Showers
Yanee Tangjai, Agnieszka Leszczynska, Tatphicha Promfu et al. (+2 more)
This study evaluates the response of the IceTop tanks to low-energy air showers in the GeV to TeV energy range based on simulated and measured count rates. Correlating this response with primary
cosmic rays provides a tool to study
Galactic and
solar cosmic-ray flux modulations, particularly for
solar particle events. We present long-term behavior of the IceTop scaler rates for a range of discriminator thresholds to better understand and calibrate the detector's response to changing environmental conditions.
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All authors Yanee Tangjai, Agnieszka Leszczynska, Tatphicha Promfu, Achara Seripienlert, Serap Tilav
High Energy Astrophysical Phenomena
Thermal Deformations in Super-Eddington Magnetized Neutron Stars: Implications for Continuous Gravitational-Wave Detectability
Hong-Bo Li, Yacheng Kang and Ren-Xin Xu
Rapidly rotating
neutron stars (NSs) are promising targets for continuous gravitational-wave (CGW) searches with current and next-generation ground-based GW detectors. In this work, we present the first study of thermal deformations in super-Eddington magnetized NSs with column
accretion, where
magnetic fields induce anisotropic heat conduction that leads to crustal temperature asymmetries. We compute the resulting mass quadrupole moments and estimate the associated CGW strain amplitudes. Our results show that
Galactic magnetized NSs undergoing super-Eddington column
accretion can emit detectable CGWs in upcoming observatories. Assuming a 2-yr coherent integration, the Einstein
Telescope and
Cosmic Explorer could detect such CGW signals from rapidly spinning NSs with
spin periods $P \lesssim 20\,\rm ms$, while the LIGO O5 run may detect systems with $P \lesssim 6 \,{\rm ms}$. These findings suggest that super-Eddington magnetized NSs could represent a new class of CGW sources, providing a unique opportunity to probe the NS crust and bridge
accretion physics with GW astronomy.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Cosmological Implications of Thermodynamic Split Conjecture
Oem Trivedi
Building on initial work on the Thermodynamic Split
Conjecture (TSC), which posits that black hole and cosmological horizon thermodynamics are generically inequivalent, we examine the consequences of that split for the Gibbons Hawking temperature and its role across cosmology. We consider many key results in both early and late universe cosmology and show that many important results such as those governing eternal inflation,
vacuum tunneling,
quantum breaking and
primordial black holes can change. The analysis further reveals that small, TSC motivated corrections to horizon thermodynamics can subtly modify Friedmann dynamics, potentially helping to address the $H_0$ and $S_8$ tensions. The work thus provides a unified route from
quantum gravity motivated thermodynamics to observational cosmology and motivates dedicated tests of the thermal laws governing the Universe itself.
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Cosmology and Nongalactic Astrophysics
Constraints of dynamical dark energy models from different observational datasets
Peiyuan Xu, Lu Chen, Guohao Li et al. (+1 more)
The measurements of
baryon acoustic oscillation by the Dark Energy Spectroscopic Instrument Data Release 2 indicate that dark energy may be dynamical with a time-varying equation of state. This has challenged the core assumptions of the $\Lambda$CDM model and aroused widespread discussion. Existing work has achieved fruitful results in the dark energy models, exploring various parameterization forms, but it lacks systematic parameter constraints based on the latest
dataset combinations. We use $\Lambda$CDM as a baseline model and carry out rigorous statistical constraints on key cosmological parameters for seven representative parameterization models. The Planck PR4 and DESI DR2 observations are incorporated into our study. We use four
datasets: CMB+BAO+PantheonPlus, CMB+BAO+DES-Y5, CMB+BAO+Union3, and CMB+BAO(without LRG1 and LRG2)+DES-Y5. Our results may not effectively alleviate ${H}_{0}$ tension, but may relatively reduce ${\sigma }_{8}$ tension. By comparing the Akaike Information Criterion and the
Bayesian evidence obtained for each model, we demonstrate that the linear Chevallier-Polarski-Linder parameterization is not the optimal choice in all cases. The Logarithmic model shows the best fitting performance among three different SNIa samples. However, with CMB+BAO(without LRG1 and LRG2)+DES-Y5, Jassal-Bagla-Padmanabhan and Chevallier-Polarski-Linder models gain more obvious preference. All two-parameter dynamical dark energy models perform most prominently in the CMB+BAO+DES-Y5
dataset, with the Logarithmic model providing strong evidence to support dynamical dark energy.
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All authors Peiyuan Xu, Lu Chen, Guohao Li, Yang Han
Astrophysics of Galaxies
Dark gaps and resonances in barred galaxies
Taehyun Kim, Dimitri A. Gadotti, Myeong-gu Park et al. (+4 more)
Dark gaps, low surface brightness regions along the bar minor axis, are expected to form as a consequence of secular
evolution in barred
galaxies. Although several studies have proposed links between dark gap locations and dynamical resonances, the results remain inconclusive. Using DESI Legacy Imaging Survey data, we find that approximately 61% of barred
galaxies exhibit pronounced dark gaps. We compare the location of dark gaps with resonance radii derived from the Tremaine-Weinberg method applied to MaNGA data for the same
galaxies. Our analysis shows that dark gaps do not preferentially form at specific resonances. Instead, their locations correlate with $\mathcal{R}$ $\equiv$ $R_{CR}/R_{Bar}$: slow bars tend to show shorter dark gap radii, while fast bars show longer ones. This trend reflects a tight relation between bar length and dark gap radius. However, when barred
galaxies are classified by their ring morphology, certain types exhibit dark gaps that align with specific resonances. Notably, dark gaps located between the inner and outer rings are closely associated with the corotation radius. In
galaxies with two dark gaps along the bar minor axis profile, the inner dark gap typically aligns with the ultraharmonic resonance, and the outer dark gap corresponds to the corotation radius. These findings suggest that some morphological types share similar $\mathcal{R}$ values and exhibit dark gaps near specific resonances. Thus, dark gaps may serve as proxies for dynamical resonances only in certain systems. Our findings may help explain the discrepancies observed in earlier studies.
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All authors Taehyun Kim, Dimitri A. Gadotti, Myeong-gu Park, Yun Hee Lee, Francesca Fragkoudi, Minjin Kim, Woong-Tae Kim
Astrophysics of Galaxies
Environmental Regulation of Dust and Star Formation Unveiled by Subaru Dual Narrow-band Imaging: Degree-scale Balmer Decrement Mapping across a z = 0.9 Supercluster
Zhaoran Liu, Tadayuki Kodama, Brian C. Lemaux et al. (+13 more)
We present results from a dual narrow-band imaging survey targeting the CL1604 supercluster at z = 0.9 using the Subaru
Telescope. By combining the NB921 filter on HSC and the NB1244 filter on SWIMS, we can detect redshifted H$\alpha$ and H$\beta$ emission lines from the supercluster. This unique technique allows us to measure both
star formation rates and
dust extinction for a sample of 94 emission-line
galaxies across the supercluster. We find that
dust extinction, estimated from the Balmer decrement (H$\alpha$/H$\beta$ ratio), increases with
stellar mass in
star-forming
galaxies, whereas relatively quiescent systems exhibit comparatively low extinction. Among
galaxies with intermediate masses ($10^{8.5} < M_* < 10^{10.5}\,M_\odot$), the
dust-corrected H$\alpha$-based
star formation rates align with the main sequence at this epoch. More massive
galaxies, however, deviate from this relation, exhibit redder colors, and reside predominantly in higher-density environments. Although
stellar mass, SFR, and
galaxy color are clearly influenced by environment, we detect no strong, systematic environmental dependence of
dust extinction for the whole sample.
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All authors Zhaoran Liu, Tadayuki Kodama, Brian C. Lemaux, Mariko Kubo, Jose Manuel Pérez-Martínez, Yusei Koyama, Ichi Tanaka, Kazuki Daikuhara, Roy R. Gal, Denise Hung, Masahiro Konishi, Kosuke Kushibiki, Ronaldo Laishram, Lori M. Lubin, Kentaro Motohara, Hidenori Takahashi
Astrophysics of Galaxies
Refining open cluster parameters with Gaia XP metallicities
M. Nizovkina, S. S. Larsen, A. G. A. Brown et al. (+1 more)
The precision of cluster parameter determination has significantly improved with the availability of homogeneous photometric
Gaia data, however, challenges such as age-
metallicity degeneracy and lack of spectroscopic observations remain. In this paper we investigate whether
metallicities derived from low-resolution
Gaia XP spectra can be effectively used to break degeneracies and improve the accuracy of OC parameter determinations. We analysed 20 OCs using isochrone fitting methods on
Gaia DR3 photometry and
metallicity estimates from several
Gaia XP-based catalogues. We derived age, distance modulus, and extinction using the Approximate
Bayesian Computation (ABC). We compared the parameter estimates to the values obtained in other works through isochrone fitting with spectroscopically constrained
metallicities or through neural network techniques applied only to the photometry. We found the systematic difference between
Gaia XP derived
metallicities and those obtained from high-resolution spectroscopy to be 0.1-0.15 dex. We found a systematic age difference of <0.03 +- 0.13 dex compared to isochrone fitting using high-resolution spectroscopy, and <0.08 +- 0.21 dex compared to neural network-based methods, and a median individual error of ~0.065 dex. Despite their low resolution,
Gaia XP
metallicities effectively constrain parameters of clusters lacking a well-populated RGB. When used with stringent quality cuts and incorporated as priors, they allow to determine ages comparable in precision to those based on high-resolution spectroscopy and more precise than photometry-only neural network methods. These results highlight the potential of
Gaia data for accurate cluster parameter analysis and detailed
Galactic studies without relying on traditional spectroscopy.
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All authors M. Nizovkina, S. S. Larsen, A. G. A. Brown, A. Helmi
Astrophysics of Galaxies
JWST Catches a Strongly Gravitationally Lensed AGN In Transition from Type II to Type I
Michael K Florian, Michael D Gladders, Gourav Khullar et al. (+10 more)
JWST has enabled the discovery of a statistical sample of obscured (type II) active
galactic nuclei (AGN) at
cosmic noon. Studies comparing those type II AGN with type I AGN at that epoch have reinforced the long-standing idea of an evolutionary link between those classes of objects. Mergers, the idea goes, disturb the morphologies and angular momentum of
galaxies. The disruption of angular momentum allows material to be funneled toward
galactic cores, sparking AGN activity and potentially also a burst of
star-formation. That material enshrouds the
galactic nucleus, leading to a type II AGN. Later, AGN feedback clears the circumnuclear
dust, leading to a transition into a type I AGN, and also quenches
star formation. If this is a common outcome, a class of intermediate objects should exist. Such objects would be somewhat disturbed and dusty and sit below the
star-forming
galaxy main sequence, and their
star-formation histories would show an increase in
star-formation at around the time of the suspected merger. We present new JWST observations of SDSSJ2222+2745, a strongly lensed AGN at z=2.801. The
lensing magnification enables a detailed study of the host
galaxy spanning the rest-ultraviolet through near infrared. JWST and HST photometry, morphological models, and models of the host's spectral energy distribution reveal that SDSSJ2222+2745 is actively transitioning from a type II to type I AGN. Catching a lensed AGN at this special evolutionary phase makes SDSSJ2222+2745 a unique laboratory to study the physical processes involved in the transition and their relationships to the AGN and the host
galaxy at incredible spatial-resolution down to about 20pc at z=2.801.
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All authors Michael K Florian, Michael D Gladders, Gourav Khullar, Keren Sharon, Aidan P Cloonan, James W Kulp, Eirk Solhaug, Brian Welch, Matthew Bayliss, Hakon Dahle, Taylor A Hutchison, Jane R Rigby, Julissa Sarmiento