High Energy Astrophysical Phenomena
The Thousand-Pulsar-Array programme on MeerKAT XIX: Single-pulse data analysis, nulling and pulse energy distributions
Michael J. Keith, Patrick Weltevrede, Lucy Oswald et al. (+8 more)
We present the Thousand
Pulsar Array (TPA) single-pulse data set, obtained with the MeerKAT
radio telescope and comprising time-series observations of 1192
pulsars, typically containing ~1000 consecutive pulses per source. We describe the MeerTime Single Pulse software pipeline which calibrates the data and automatically excises interference signals to produce data products suitable for typical single-pulse studies. To demonstrate the capabilities of the
dataset, we carry out a population-level study of phase-averaged single-pulse energy distributions and nulling behaviour. Pulse energy distributions are modelled within a
Bayesian framework choosing from a range of intrinsic energy distributions, and including an explicit nulling fraction. We find that approximately half of the
pulsars require multi-component intrinsic energy distributions, while the remainder are consistent with single-component models. Nulling is detected or constrained for most
pulsars in the sample, and both the occurrence and inferred nulling fraction show systematic variation across the P-$\dot{P}$ diagram. In particular, nulling fractions increase with
spin period and exhibit only a weak dependence on period derivative. We also examine trends in the preferred forms of pulse energy distributions as a function of
spin-down luminosity, finding modest evidence for population-level
evolution. Estimates of single-pulse luminosities indicate that individual pulses can exceed the long-term average luminosity by large factors, particularly for low-$\dot{E}$
pulsars. These results characterise the statistical properties of single-pulse emission across a large
pulsar sample and highlight the limitations of phase-averaged energy distributions for capturing the full complexity of
pulsar emission variability.
Read the full abstract ▾
All authors Michael J. Keith, Patrick Weltevrede, Lucy Oswald, Aris Karastergiou, Xiaoxi Song, Haoyue Wang, Jui-An Hsu, Simon Johnston, Geoff Wright, Matthew Bailes, Maciej Serylak
Instrumentation and Methods for Astrophysics
On-sky demonstration of reinforcement learning for adaptive optics control
Jalo Nousiainen, Vincent Chambouleyron, Benoit Neichel et al. (+7 more)
Reinforcement learning (RL)-based
algorithms have recently emerged as a promising approach for adaptive optics (AO) control. In simulations and laboratory experiments, they have demonstrated robustness to real-world effects such as
photon and detector noise, misregistration, vibrations, and rapid variations in seeing conditions. However, their performance has not yet been validated on sky. We report the first on-sky demonstration of a reinforcement learning controller for adaptive optics, named Policy Optimization for AO (PO4AO). We further analyze its on-sky behavior and identify directions for improving the
algorithm and its implementation.PO4AO was implemented and deployed on the Papyrus adaptive optics system installed at the Coudé focus of the 1.52 m
telescope (T152) at the OHP. A Python-based implementation was interfaced with the existing real-time controller (DAO RTC) via shared-
memory buffers. The performance of PO4AO was compared to that of a standard integrator controller over several nights, covering a range of flux levels and atmospheric conditions. PO4AO consistently outperformed the standard integrator in all tested configurations. The controller successfully learned and compensated for vibration patterns and demonstrated strong robustness to measurement noise. Once tuned for Papyrus, PO4AO operated in a turnkey fashion, using a single set of hyperparameters across varying observing conditions and science targets. These performance gains were achieved despite a non-optimized Python implementation introducing approximately $750\,\mu\text{s}$ of additional latency, along with control jitter and occasional frame drops. When properly implemented and optimized, PO4AO constitutes a robust and high-performance turnkey controller for single-conjugate adaptive optics systems, paving the way for broader adoption of reinforcement learning strategies in on-sky AO operations.
Read the full abstract ▾
All authors Jalo Nousiainen, Vincent Chambouleyron, Benoit Neichel, Sylvain Cetre, Jean-Francois Sauvage, Angelie Alagao, Markus Kasper, Jonathan Dray, Romain Fetick, Byron Engler
Solar and Stellar Astrophysics
Amortized Simulation-Based Inference of Colliding-Wind Binaries from Short, Noisy Image Time Series
Niklas Knöll, Tobias Buck, Lorenzo Branca et al. (+1 more)
Colliding-wind binaries (CWBs), which are systems of two massive
stars whose supersonic winds collide into bow shocks, encode rich information about
stellar wind properties in their multi-frequency emission, e.g. images in the H$\alpha$, X-ray, and
radio wavelengths. Inferring physical parameters (mass-loss rates, terminal wind velocities, orbital elements) from short time-series observations is a compelling but challenging inverse problem, because the forward hydrodynamic simulator is computationally expensive and the likelihood is intractable. We adopt a factorized spatio-temporal architecture for amortized posterior inference that separates spatial encoding from temporal aggregation. This design aligns with the structure of the underlying physical process of local morphology and global dynamical
evolution, induces time-translation equivariance in the learned representation, and improves identifiability in low-signal regimes. Coupled with a neural spline flow conditioned on these spatio-temporal
embeddings of 10-frame H$\alpha$
photon-count time series, we present a complete simulation-based inference pipeline for CWBs. Our method jointly infers seven physical parameters from synthetic observations under realistic detector noise, with posteriors verified as well-calibrated via TARP and SBC diagnostics. The approach naturally expands posterior width in information-poor regimes (low
photon counts) and robustly recovers orbital parameters and mass-loss rates, demonstrating the feasibility of amortized likelihood-free inference for this challenging astrophysical inverse problem.
Read the full abstract ▾
All authors Niklas Knöll, Tobias Buck, Lorenzo Branca, Giuseppe Viterbo
Instrumentation and Methods for Astrophysics
SUPPPPRESS: Prototyping and testing liquid-crystal vector vortex coronagraphs with reduced polarization leakage
Rico Landman, David Doelman, Jeroen Rietjens et al. (+16 more)
The
vortex coronagraph is one of the most promising candidates for the Habitable Worlds Observatory (HWO) due to its excellent theoretical performance for an off-axis
telescope. A practical realization can be achieved using
liquid-
crystal polymers to form a vector
vortex coronagraph (VVC). Reaching the $10^{-10}$ contrast required for Earth-like
planet detection is, however, limited by polarization leakage caused by wavelength-dependent deviations from half-wave retardance. This effect can be mitigated using multi-layer twisted retarders to minimize leakage, and by combining the VVC with multiple polarization gratings (mgVVC) to diffract the polarization leakage out of the science path. We present recent progress within the ESA-funded SUPPPPRESS project, which aims to advance the manufacturing, assembly, and testing of high-performance VVCs. Central singularities of 2 and 6 $\mu$m have been achieved for charge 2 and charge 6 VVCs, respectively, with patterning accuracies better than 1 degree root-mean-square error. Fabrication procedures have been developed to produce individual components with a polarization leakage of $3\times10^{-4}$ over a 10% bandwidth and $8\times10^{-4}$ over a 20% bandwidth. We also report on the development of assembly and
alignment procedures for mgVVCs and their metrology. Furthermore, we present initial high-contrast tests at the THD2 bench for both regular VVCs and a double-grating VVC. The double-grating VVC reaches an average contrast between 3 and 10 $\lambda$/D of $2 \times 10^{-8}$ over a small bandwidth and $6\times 10^{-8}$ over a 10% bandwidth. Finally, we report on successful space-environment tests of the assembled
liquid-
crystal masks.
Read the full abstract ▾
All authors Rico Landman, David Doelman, Jeroen Rietjens, Iva Laginja, Pierre Baudoz, Kristien Peeters, Chris van Dijk, Yuki Nishie, Yuta Watanabe, Alexander Eigenraam, Mario Vretenar, Joost van den Born, Raphaël Galicher, Johan Mazoyer, Axel Potier, Mariya Krasteva, Matteo Taccola, Felix Bettonvil, Frans Snik
Instrumentation and Methods for Astrophysics
UnReal-B : Real-Space DFT Solver for Matter in Extreme Magnetic Fields
Bhalchandra S. Pujari, Andrey Tokarev and Dipanjan Mitra
As new observational technologies reveal increasingly detailed properties of
neutron star surfaces, the demand for accessible and extensible theoretical modeling tools continues to grow. We present UnReal-B, a real-space Density Functional Theory solver for one-dimensional chains of matter in extreme
magnetic fields $B \approx 10^{12} - 10^{15},\mathrm{G}$. By employing the adiabatic approximation, UnReal-B, provides a streamlined numerical framework for calculating the electronic structure of strongly magnetized condensed matter. The solver is benchmarked against published results for several astrophysically relevant elements, demonstrating excellent agreement while maintaining a comparatively simple and transparent implementation. Released as open-source software, UnReal-B facilitates reproducible and community-driven investigations of
neutron-
star surface matter and provides a foundation for future developments motivated by emerging observational constraints.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Potential detection of ~ 4.2 keV emission line from GRS 1747-312
Amom Lanchenbi Chanu, Akash Garg, Ranjeev Misra et al. (+1 more)
We present a broadband spectral analysis of the
neutron star LMXB GRS 1747-312 using $\sim$ 40 ks AstroSat data. The source was observed during the decay phase of the 2017 outburst, with an absorbed 1.0-5.5 keV flux of 1.67$^{+0.04}_{-0.07}\times$10$^{-11}$ erg s$^{-1}$ cm$^{-2}$, corresponding to a luminosity of $\sim$(0.9-1.80)$\times$10$^{35}$ erg s$^{-1}$. The continuum is modeled with thermal Comptonization of blackbody emission and interstellar absorption. A mildly broad iron line at $\sim$6.4 keV is fitted with a disc reflection component. Narrow lines below 2 keV are described by a hot
plasma using the XSPEC model APEC. Additionally, there is a potential detection of an emission line at 4.19$^{+0.12}_{-0.10}$ keV with width $\sigma$ = 0.2 $\pm$ 0.2 keV and line flux of 13$^{+10}_{-9}\times$10$^{-5}$ erg s$^{-1}$ cm$^{-2}$. Examination of several short-duration ($\sim$ few kiloseconds) Swift observations at a few times the AstroSat source flux provided upper limits to the line flux of $<$30$\times$10$^{-5}$ erg s$^{-1}$ cm$^{-2}$. The 4.2 keV line likely originates from reflection off the
neutron star surface. Shifting the neutral Fe K$_\alpha$ line from its rest energy of 6.4 keV to 4.2 keV requires a
redshift of z $\sim$ 0.6, consistent with that expected from the surface of a non-spinning 1.4 M$_\odot$, 10 km radius
neutron star. If confirmed, this feature provides a potential direct measurement of gravitational
redshift, allowing us to place strong constraints on the
neutron star's mass-to-radius ratio and gain valuable insights into the equation of state (EOS) of dense matter.
Read the full abstract ▾
All authors Amom Lanchenbi Chanu, Akash Garg, Ranjeev Misra, A. Senorita Devi
Instrumentation and Methods for Astrophysics
DIffuse X-ray Explorer (DIXE): Sky Survey Strategy and Collimator Response Demodulation
Jiejia Liu, Chunyang Jiang, Junjie Mao et al. (+3 more)
DIffuse X-ray Explorer (DIXE) is a proposed high-resolution X-ray spectroscopic surveyor aimed at studying large structures of hot gas in the Milky Way. Its payload is designed to have a field of view (FoV) of $10^\circ$ (half-power diameter) and an energy resolution of better than 6 eV, covering an energy range of 0.1-10 keV. It will be mounted on the China Space Station (CSS) and follow the CSS orbit to conduct the survey with fixed zenith pointing in order to optimize the coverage of key science targets. The payload will avoid the Sun passively via an operable sunshade, where a minimum $25^\circ$ angular separation between the pointing axis and the direction of the Sun is required. Two Sun-avoidance strategies are considered: one focusing on minimizing mechanical risk and the other on maximizing exposure time. The one-year exposure maps indicate that DIXE will cover approximately $72.5\%$ of the sky, with typical exposure times of 26 ks and 68 ks for the two strategies, respectively. Although mechanically collimated, the imaging performance of the payload can be enhanced with a demodulation method based on Markov Chain Monte Carlo sampling using the collimator response. Through simulation, we found that the method could achieve a localization accuracy of $1^\circ$ for point-like sources and a spatial resolution of $3^\circ$ for the extended sources of complex surface brightness distribution, both of which are significantly smaller than the FoV.
Read the full abstract ▾
All authors Jiejia Liu, Chunyang Jiang, Junjie Mao, Rui Huang, Ruixuan Tian, Wei Cui
High Energy Astrophysical Phenomena
Hubble as a Unique Discovery Engine of the Fate of Massive Stars and Black Hole Formation
Avishai Gilkis, Eva Laplace, Charles D. Kilpatrick et al. (+3 more)
How
stellar-mass black holes are formed is an open question in astrophysics, with very limited observational constraints. It is not known which types of
stars are more likely to produce black holes, and whether the formation process is accompanied by strong or weak electromagnetic transients - or none at all - and this issue remains a critical missing piece in the puzzle of the fate of massive
stars. Recent theoretical work predicts that many
stellar-mass black holes form from hot, UV-luminous massive
stars, including Wolf-Rayet-like progenitors, and searches focused primarily on luminous cool supergiants may therefore miss a substantial fraction of black-hole formation events. While the coming decade will bring major advances in time-domain astronomy through Rubin/LSST, Roman, JWST, and wide-field transient surveys, none of these combines UV sensitivity, sub-arcsecond imaging, and decade-long continuity. HST uniquely enables direct searches for disappearing hot massive
stars associated with black-hole formation. We outline a roadmap for extending HST's role in this area into the 2030s through a dedicated, large program to re-image nearby
galaxies in the UV and identify candidate disappearing
stars and unusual low-luminosity transients identified by complementary surveys. Theoretical event rates imply that the nearby
galaxy population accessible to HST should yield of order one detectable black-hole-forming disappearance event per year. Extending HST operations into the 2030s would therefore provide crucial insights into the unsolved problem of black hole formation.
Read the full abstract ▾
All authors Avishai Gilkis, Eva Laplace, Charles D. Kilpatrick, Maria R. Drout, Anna J. G. O'Grady, Christopher A. Tout
Earth and Planetary Astrophysics
A Processing Workflow for Cassini VIMS Jupiter Cubes
Asier Anguiano-Arteaga, Patrick G.J. Irwin, Santiago Pérez-Hoyos et al. (+2 more)
We present a calibrated catalog of Cassini Visible and Infrared Mapping Spectrometer (VIMS) observations of Jupiter, together with the processing workflow used to generate the final publicly available products. Starting from the raw VIMS cubes, the workflow produces radiometrically consistent multi-extension FITS files and includes a revised visible-channel calibration, a revised infrared-channel calibration that resolves a subset of problematic cases not satisfactorily treated by the standard ISIS pipeline, corrections for pointing-related misalignments between spectral cubes and
geometric backplanes, and customized dark signal correction strategies. The final products include calibrated spectral cubes together with geometry backplanes and wavelength information for subsequent scientific analysis. We assess the consistency of the calibrated products through internal validation tests and comparisons with independent reference spectra from the literature. The resulting products provide a uniform and validated data set of Cassini VIMS Jupiter observations for community use. The full catalog is available as a public data set at Zenodo: doi:10.5281/zenodo.19223781.
Read the full abstract ▾
All authors Asier Anguiano-Arteaga, Patrick G.J. Irwin, Santiago Pérez-Hoyos, Davide Grassi, Emiliano D'Aversa
Instrumentation and Methods for Astrophysics · Cross-listed from physics.comp-ph
An adaptive framework for the axisymmetric pulsar magnetosphere using physics-informed Kolmogorov-Arnold networks
Spyros Rigas, Ioannis Contopoulos, Georgios Alexandridis et al. (+1 more)
The
pulsar magnetosphere has only recently been addressed using Physics-Informed Neural Networks (PINNs), by deploying a domain-decomposition approach and treating the separatrix and equatorial current sheet as infinitesimally thin discontinuities. However, this baseline requires extensive manual hyperparameter tuning, achieves limited final accuracy and demands several hours of training. We refine this framework by introducing domain-specific neural architectures based on Kolmogorov-Arnold networks, an automated adaptive training pipeline and a physics-based convergence criterion that eliminate the need for manual calibration. The proposed methodology delivers self-consistent axisymmetric magnetosphere solutions with mean squared errors of the PDE residuals at O(1e-6) in double precision - an improvement of two orders of magnitude over the baseline - while achieving convergence in under 20 minutes in single precision. Importantly, the method reliably resolves
stellar radii reduced by up to 80% compared to the baseline, overcoming the severe spatial scale disparities that also challenge traditional solvers. Furthermore, by varying the flux that opens to infinity, we provide a correction to the equation that connects it to the equatorial T-point's position. The complete framework is released as the open-source library PulsarX.
Read the full abstract ▾
All authors Spyros Rigas, Ioannis Contopoulos, Georgios Alexandridis, Antonios Nathanail
Cosmology and Nongalactic Astrophysics
Balancing bias, baryons, and scale cuts in LSST 3x2pt analysis
Ottavia Truttero, Maria Tsedrik, Joe Zuntz et al. (+4 more)
Stage IV surveys such as LSST will probe deeply into the nonlinear regime, where systematic effects from
galaxy bias and baryonic feedback become dominant and poorly constrained nuisance parameters can lead to degeneracies. In this work we present a 3x2pt analysis for LSST Y1 and Y10 data using the BACCO emulator for modelling both the hybrid-effective field theory (HEFT) for nonlinear
galaxy bias and the baryonic feedback using the baryonification mechanism. We aim to find a balance between model complexity and scale cuts, with particular
attention to parameter degeneracies and baryonic feedback effects on the
galaxy-matter and
galaxy-
galaxy power spectra. First, we find that a linear bias model delivers percent-level unbiased constraints on $\Omega_{\rm m}$ and $\sigma_8$ only up to $k_{\rm max}=0.1 h/$Mpc, but pushing to smaller scales requires a perturbative approach. Second, we compare HEFT with a minimal bias variant with fixed higher-order terms, and find that the latter is unbiased in $\Lambda$CDM even at $k_{\rm max}=0.7 h/$Mpc. We show that higher-order bias can mimic baryonic suppression, but
baryons cannot reproduce the full range of higher-order bias behaviour within the parameter range allowed by the BACCO baryonification model. Third, we find that a detection of the total
neutrino mass $M_\nu$ is possible for both Y1 and Y10 for $k \geq 0.5 h/$Mpc, at least when photo-$z$ uncertainties and related nuisance parameters are precisely known. However, the specific measured value is not robust across equally plausible mock scenarios: the inferred $M_\nu$ can be significantly biased by adopting the minimal bias model. The entire analysis is conducted with a new independent, open source pipeline MGL that we present for the first time in this work.
Read the full abstract ▾
All authors Ottavia Truttero, Maria Tsedrik, Joe Zuntz, Alkistis Pourtsidou, Nikolina Šarčević, Christos Georgiou, the LSST Dark Energy Science Collaboration
Earth and Planetary Astrophysics
Full one-fluid dusty gas with multiple grain species in SPH
Mark Hutchison, Guillaume Laibe, Giovanni Tedeschi-Prades et al. (+5 more)
We present a Smoothed Particle Hydrodynamics (SPH) implementation of the full one-fluid dusty gas
algorithm for multiple
dust species, generalising our previous terminal velocity approach to handle arbitrary drag regimes. By construction, mass, momentum, angular momentum, and energy are all conserved. We
benchmark our method against a suite of tests – DUSTYBOX, DUSTYWAVE, DUSTYSHOCK, DUSTYSETTLE, and DUSTYDISC – each probing different aspects of the
algorithm. Compared to the terminal velocity approximation, the full one-fluid approach incurs a computational cost increase of a factor of five to ten due to the added overhead of evolving the differential velocities and solving the drag terms implicitly. However, it accurately recovers analytic behaviour in regimes where the terminal velocity approximation fails. In such cases, errors from the terminal velocity approximation accumulate and propagate to other
dust phases. We show that the stopping-time limiter commonly used in the terminal velocity approximation for numerical stability can substantially affect simulations containing large grains (Stokes numbers $\gtrsim 1$). While disabling the limiter leads to different outcomes, the discrepancy with the full one-fluid solution remains comparable, underscoring the importance of using a more general formulation for large grains. The full one-fluid formalism may be useful when including processes such as coagulation and fragmentation, where accurate treatment of large grains becomes essential. While the inability to model orbit-crossing
dust trajectories remains a key limitation of the one-fluid formalism, this may eventually be addressed through the introduction of an effective
dust pressure, mirroring how fluid models encapsulate microscopic velocity dispersion in gases.
Read the full abstract ▾
All authors Mark Hutchison, Guillaume Laibe, Giovanni Tedeschi-Prades, Timothée David-Cléris, Alex Barret, Maxime Lombart, Daniel J. Price, Christine M. Koepferl
Astrophysics of Galaxies
Optical-morphology-based assessment of astrometric quality in Gaia-CRF3 quasars
Qiqi Wu, Shilong Liao, Zhaoxiang Qi et al. (+3 more)
Context. Several studies have shown that host-
galaxy structure or extended optical morphology in AGNs can induce spurious parallaxes and proper motions in
Gaia DR3. However, it remains unclear whether source morphology also introduces systematic errors into the celestial reference frame constructed from
Gaia data. Aims. We aim to provide a
Gaia-independent external morphological indicator for
Gaia-CRF3 sources and to use it to quantify the astrometric systematics associated with source morphology. Methods. Using morphological parameters derived from DESI, SDSS, and SkyMapper, together with the PS1-PSC point-source score as a common reference scale, we used XGBoost to infer external morphological scores for
Gaia-CRF3 sources. We then developed a multi-survey fusion scheme to combine the four survey-based point-source scores into a single composite score that measures the degree to which each source departs from the morphology of an ideal point source. Results. We obtained morphological scores for 1,607,490
Gaia-CRF3 sources, corresponding to a completeness of 99.59% with respect to the full
Gaia-CRF3 catalogue. The score ranges from 0 to 1 and remains reliable for sources with $G<20.85$ mag. Based on this indicator, we find that AGNs with strongly non-point-like morphology induce a parallax zero-point shift of about $-43.7\,\mu$as, which cannot be effectively removed by the current parallax zero-point correction model. We also find that reference-source subsamples selected in different score ranges exhibit significantly different all-sky proper motion fields. For the high-purity point-source subsample with point\_score > 0.95, the total frame
spin amplitude is reduced by 15.8% relative to that of the full
Gaia-CRF3 sample.
Read the full abstract ▾
All authors Qiqi Wu, Shilong Liao, Zhaoxiang Qi, Qi Xu, Ye Ding, Keyu Zhu
Astrophysics of Galaxies
Star-formation variability on the star-forming main sequence during the Epoch of Reionization
H. T. J. Bevins, S. Tacchella and C. Simmonds
Star formation in
galaxies is intrinsically
stochastic, driven by physical processes operating across a wide range of scales. The scatter in the
star-forming main sequence relation provides a window into this variability, but interpreting this scatter in terms of underlying physical mechanisms remains challenging. We present a study of
star-formation variability during reionization (
redshift z=3-8) using power spectral density (PSD) models to characterize fluctuations in
star formation rates (SFRs). We use estimates of the intrinsic scatter in main sequence SFRs at six averaging timescales (10-100 Myr) from a catalogue of ~17000
galaxies presented in Simmonds et al. 2025 to constrain two PSD models, the Simple Harmonic Oscillator (SHO) and the Extended Regulator (ExtReg), with nested sampling and neural network emulators. We find that the regulator component of the ExtReg model is poorly constrained by the present data. However, both the dynamical component of the ExtReg model and the single-component SHO model favour characteristic variability timescales of ~10-30 Myr, comparable to expected
galactic dynamical and
stellar feedback timescales. At least in the SHO model, and most clearly at z~3-4, the inferred PSD power on ~10 Myr timescales decreases with
stellar mass, indicating more bursty, rapidly varying
star formation in lower-mass
galaxies than in higher-mass systems. We find weak evidence for a transition from a two-component ExtReg-like PSD at lower
redshift to a single-component SHO-like PSD at higher
redshift in the lowest
stellar-mass bin, log M*/M$\odot$ = 8-8.5, although the Bayes factors are small and selection effects at high
redshift prevent strong conclusions. Overall, our results suggest that the observed 10-100 Myr scatter of the high-
redshift star-forming main sequence is governed primarily by short-timescale variability, consistent with
galactic dynamical timescales.
Read the full abstract ▾
Earth and Planetary Astrophysics
Multi-epoch scattered-light analysis of HD 135344B: new evidence for a spiral-driving protoplanet
J. Latour, V. Christiaens, O. Absil et al. (+17 more)
The HD 135344B (SAO 206462) disk exhibits strong signposts of
planet formation. ALMA images in the sub-mm revealed a gap-crossing
dust filament whose position coincides with a twist detected in the scattered-light spiral structure. Analysis of the spirals in polarized light also hints at a spiral-driving protoplanet in the sub-mm gap. We aim to study the spirals dynamics, as well as the twist, over a 10-year baseline, in different bands. We also seek to assess the authenticity of a recently claimed candidate protoplanet. We use high-fidelity post-processing
algorithms such as IPCA to minimize the biases induced by ADI on extended sources and analyze archival VLT/NACO, VLT/SPHERE, VLT/ERIS and JWST/NIRCam
datasets to obtain the spiral traces and measure their orbital motion in multiple scattered light bands. We measure an average spiral orbital motion of 0.81$\pm$0.05 deg/yr, in agreement with the literature value of about 0.85$\pm$0.05 deg/yr at all wavelengths. With simple modeling of the twist morphology, we confirm that it is co-moving with the spiral in which it is embedded. While the position angle of the twist coincides with the
dust filament, it is located at a smaller angular separation from the
star, which we attribute to the fact that the spiral trace moves away from the central
star with increasing wavelength. We find that a recently claimed protoplanet candidate can be explained as a post-processing artifact. Our confirmation that the motion of the scattered light twist is consistent with the orbital velocity of a
planet at 69$\pm$4 au over a 10-year baseline suggests that the spirals, the gap, the
dust filament, and the twist, could indeed be attributed to the same hypothetical protoplanet embedded within the spiral. A perplexing trend for a wavelength-dependence of the angular distance of the spiral traces to the central
star remains to be explained.
Read the full abstract ▾
All authors J. Latour, V. Christiaens, O. Absil, M. Bonse, R. Savonet, S. Juillard, I. Hammond, S. Casassus, L. Cieza, G. Cugno, C. Desgrange, S. Lacour, D. Mawet, M. Montesinos, S. Perez, C. Pinte, M. Reggiani, T. Stolker, N. van der Marel, A. Zurlo
Astrophysics of Galaxies
Rogue Ones: Orbital census of Galactic Cepheids and their Anomalies
Shourya Khanna, Ronald Drimmel, Eloisa Poggio et al. (+2 more)
Classical Cepheids (DCEPs) are excellent standard candles expected to trace the spatial and kinematic distribution of the
Galaxy's young and dynamically cold
stellar disc. Using the most precise mid-infrared DCEP distances to date combined with
Gaia-DR3 astrometry and line-of-sight velocities, we perform a comprehensive 6D dynamical census of the Milky Way's DCEP population. While the vast majority exhibit the expected disc-like kinematics, we identify 18 kinematically anomalous Cepheids. These `rogue'
stars reside on highly inclined orbits (three at > 70 degrees), including two in retrograde motion and one with a total velocity of ~480 \kms. Despite their extreme trajectories, their optical light curves are consistent with DCEP classifications. We explore whether these anomalies originate from possible classification systematics or physical processes and find only three of our sources are likely misclassified. Assuming a runaway scenario we derive dynamical ages for the kinematic anomalies, which we find highly consistent with their Cepheid ages. Spectroscopic follow-up would be insightful as one source in particular is exceptionally metal poor ([Fe/H] ~ -1.6 dex), which is highly atypical for a DCEP. Integrating photometric classification with 6D kinematics will help fully characterise the
Galaxy's variable
star populations.
Read the full abstract ▾
All authors Shourya Khanna, Ronald Drimmel, Eloisa Poggio, Dorota M. Skowron, Jie Yu
Cosmology and Nongalactic Astrophysics
Synergy between the gravitational potential decay rate and other structure growth probes in testing gravity
Shang Li, Pengjie Zhang and Fuyu Dong
We test
gravity by exploiting the synergy between the gravitational potential decay rate ($\mathit{DR}$) and complementary structure-growth probes: these observables respond to MG parameters with different degeneracy directions, so their combination yields stronger constraints than any single probe. We adopt the tomographic $\mathit{DR}$ measurements reported in \citep{2025ApJ...982...99D} and combine them with CMB-
lensing-
tomography $\Sigma_8$ measurements and $f\sigma_8$ measurements from DESI DR1 full-shape analyses and the DESI peculiar-velocity field. We apply this joint data vector to two representative frameworks: phenomenological parameterizations and the Effective Field Theory (EFT) $\alpha$-basis. For the phenomenological form $P_{\rm MG}(a)=1+P_{{\rm MG},0}\,\Omega_{\rm DE}(a)/\Omega_{\rm DE}(0)$, where $P_{\rm MG}$ denotes $\mu$, $\eta$, or $\Sigma$, we obtain $\mu_0=0.09\pm0.35$ and $\Sigma_0=0.01\pm0.06$. Compared to the measurements combination $\Sigma_8+f\sigma_8$, including $\mathit{DR}$ tightens the constraint on $\Sigma_0$ by a factor of $\sim2$. For the $(\mu_0,\eta_0)$ case we find $\mu_0=0.06^{+0.17}_{-0.23}$ and $\eta_0=-0.03^{+0.36}_{-0.46}$; relative to $\Sigma_8+f\sigma_8$, adding $\mathit{DR}$ improves the constraints on both parameters by a factor of $\sim1.5$. In the EFT $\alpha$-basis, adopting the parameterization $\alpha_i(a)=c_i\,\Omega_{\rm DE}(a)$ with $i\in\{{\rm M,B}\}$, we find $c_{\rm M}=0.64^{+0.32}_{-0.72}$ and $c{\rm B}=0.31^{+0.19}_{-0.29}$. The corresponding EFT uncertainties are about a factor of $\sim2$ smaller than those reported in \citep{2025JCAP...09..053I}, which combined DESI full-shape and BAO measurements with DES-SN5YR and CMB data. These results demonstrate the capability of $\mathit{DR}$ and the necessity of including the $\mathit{DR}$ measurements in testing
gravity.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Discovery of EP J175257.3-351923 as a Candidate Black Hole Low-Mass X-ray Binary
G. L. Huang, Q. C. Zhao, L. Tao et al. (+30 more)
We report the discovery of a new X-ray transient, EP J175257.3-351923 (EP250916a), by the Einstein Probe (EP) near the
Galactic plane. The outburst lasted for at least 250\,days, reached a peak 2–10 keV flux of $\sim 4 \times 10^{-10}$~erg~cm$^{-2}$~s$^{-1}$, and exhibited a fast-rise exponential-decay (FRED) profile typical of X-ray binary outbursts. The source remained in the hard state throughout the outburst, with only modest variations in the
photon index ($\sim 1.6$–$2.2$) and no evidence for a spectral state transition. Broadband spectral modeling suggests a truncated disk, a weak reflection component, and a high-energy cutoff at $\sim 217$~keV, consistent with hard-state
accretion in black-hole systems. No reliable optical or
radio counterpart is detected within the Swift/XRT error circle. The inferred X-ray-to-optical and X-ray-to-
radio flux ratios are consistent with a low-mass X-ray binary classification. Neither pulsations nor significant aperiodic variability are detected. Although the compact object cannot yet be firmly identified, the timing, spectral, and multiwavelength evidence favors EP~J175257.3–351923 as a black-hole low-mass X-ray binary candidate, highlighting EP's potential to uncover a faint, previously hidden population of X-ray binaries.
Read the full abstract ▾
All authors G. L. Huang, Q. C. Zhao, L. Tao, A. Coleiro, A. Rau, S. Brennan, C .Y. Dai, R. Soria, F. Cangemi, F. Coti Zelati, A. Marino, L. Zhang, S. Guillot, H. Q. Cheng, H. Feng, D. Götz, Y. Huang, Y. F. Huang, D. Y. Li, Z. S. Li, P. Maggi, R. C. Ma, X. Ma, H. W. Pan, N. Rea, J. Wang, Q. Y. Wu, L. P. Xin, W. M. Yuan, Z. H. Yao, G. B. Zhang, W. D. Zhang, S. N. Zhang
Astrophysics of Galaxies
Hector Galaxy Survey: Linking the low- and high-mass ends of the initial mass function in star-forming galaxies
Diego Salvador, Andrew Hopkins, Matt Owers et al. (+30 more)
The
stellar initial mass function (IMF) is a fundamental ingredient in
galaxy evolution, linking observed integrated light to
galaxy properties. Constraining the full IMF shape beyond the Milky Way remains challenging, as most studies focus either on the low-mass end of quiescent
galaxies or the high-mass end of
star-forming
galaxies. Here we present the first simultaneous analysis of both ends of the IMF in 214
star-forming
galaxies from the Hector survey. We estimate the low-mass end slope using a
stellar population approach that fits IMF-sensitive absorption features with extended
star formation histories, while the high-mass end slope is derived via the Kennicutt diagnostic, which compares the observed H-alpha equivalent width and g-r colour with
stellar population synthesis model predictions. We find substantial diversity in IMF shapes and a weak but statistically robust correlation between the low- and high-mass IMF slopes. Both IMF slopes show significant correlations with
stellar mass,
star formation activity, and
stellar metallicity ([M/H]). In general, higher
stellar mass, stronger
star formation activity, and higher
metallicity are associated with both bottom-heavy and top-heavy IMFs. Partial correlation analysis reveals that the low-mass end slope is primarily driven by [M/H], whereas the high-mass end is mainly linked to
stellar mass and recent
star formation. Because the low-mass end slope traces the IMF over long-term averages and the high-mass end slope captures only recent
star formation, the processes shaping each end likely occur over different and possibly decoupled timescales. Our findings challenge the universality of the IMF and emphasise the need for
galaxy evolution and
stellar population models to incorporate a flexible IMF prescription. Accounting for these variations is essential to build an IMF-consistent picture of
galaxy evolution across
cosmic time.
Read the full abstract ▾
All authors Diego Salvador, Andrew Hopkins, Matt Owers, Ignacio Martín-Navarro, Gabriella Quattropani, Pratyush Kumar Das, Mina Pak, Scott Croom, Julia Bryant, Tereza Jerabkova, Karl Glazebrook, Andrei Ristea, Madusha Gunawardhana, Sarah Sweet, Kyuseok Oh, Jong Chul Lee, Joon Hyeop Lee, Caroline Foster, Tayyaba Zafar, Yifan Mai, Sujeeporn Tuntipong, Jesse van de Sande, Stefania Barsanti, Joss Bland-Hawthorn, Matthew Colless, Robert Content, Tony Farrell, Jon Lawrence, Seong-sik Min, Sree Oh, Naveen Pai, Ayoan Salim Sadman, Ross Zhelem
Astrophysics of Galaxies
Molecular Gas Structure and Star Formation Diversity in Stephan's Quintet Revealed by ACA CO(1-0) Mapping
Misaki Yamamoto, Fumiya Maeda, Kazuyuki Muraoka et al. (+10 more)
We present $^{12}$CO(1-0) mapping across the entire system of Stephan's Quintet, a well-known compact
galaxy group, observed by Atacama Compact Array (7\,m array + Total Power) of the Atacama Large Millimeter/submillimeter Array. These observations provide the first large-scale ($137\,\mathrm{kpc}\times119\,\mathrm{kpc}$), spatially resolved ($\sim$5.5\,$\mathrm{kpc}$) molecular gas map of a compact group. Our CO map revealed that most of the molecular gas resides in the disk of the member
galaxy NGC~7319 and in the intergalactic regions, including components along the shocked filament and the optically identified
tidal tail extending from NGC~7319. Along the
tidal tail and its surroundings, we found not only an extended molecular gas component but also four discrete CO clumps, with velocity dispersions of $\sim$10-30 $\mathrm{km\,s^{-1}}$ and molecular gas masses of order $10^7$-$10^8\,M_\odot$. Three of these clumps spatially overlap with H\,i, whereas the remaining clump shows no associated H\,i or counterparts at optical and infrared wavelengths. Using
star formation rates derived from H$\alpha$ luminosities of H\,ii regions, we found that
star formation efficiencies (SFEs) span $\sim$2.2\,dex ($\sim$0.02–4\,Gyr$^{-1}$) and negatively correlate with CO velocity dispersion. While regions with small velocity dispersion exhibit SFEs comparable to those of nearby disk
galaxies, those with large velocity dispersion ($\sim$50-150$\,\mathrm{km\,s^{-1}}$) around the shocked filament show strongly suppressed
star formation. These results suggest that
turbulence plays a significant role in regulating
star formation in interacting systems.
Read the full abstract ▾
All authors Misaki Yamamoto, Fumiya Maeda, Kazuyuki Muraoka, Fumi Egusa, Shinya Komugi, Bunyo Hatsukade, Hiroyuki Kaneko, Masato I.N. Kobayashi, Kotaro Kohno, Ayu Konishi, Kana Morokuma-Matsui, Kouichiro Nakanishi, Kouji Ohta
High Energy Astrophysical Phenomena
Updating the PATH framework with FRB host galaxy models
C. W. James, N. Loudas, M. Woodland et al. (+5 more)
Over a hundred fast
radio burst (FRB) host
galaxies have now been identified, enabling both comparisons of host
redshift with FRB dispersion measure to study the cosmological distribution of ionised gas, and analyses of host properties in order to identify FRB progenitors. The standard method for determining the most likely FRB host
galaxy in an optical image is the
Bayesian framework Probabilistic Association of Transients to their Hosts (PATH), which accounts for uncertainties in the
radio localisation, and simplified prior distributions on the host being observable. In this work we extend PATH, incorporating physically-motivated priors that are based on expectations about FRB host
galaxy magnitudes. We develop three different models for the apparent r-band magnitude distribution based on an FRB's expected host
galaxy redshift, $P(m_r|z)$ and combine these with expectations for
redshift based on an FRB's dispersion measure, $P(z|DM)$. We fit the parameters of these prior models using host
galaxy candidates for 32 FRBs detected by the Australian SKA Pathfinder (ASKAP) in incoherent sum (ICS) mode by the Commensal Real-time ASKAP Fast Transients (CRAFT) survey. Employing PATH with the new priors on the host magnitudes, we find increased confidence in the most probable hosts of all ASKAP ICS FRB host
galaxies. All three models predict similar distributions of FRB host magnitudes at low
redshift $(z \sim 0.1)$, and we confirm previous results that the true FRB host
galaxy distribution is fainter than expected for a
star-formation-weighted distribution (p-value of 0.12%). However, a mass-weighted distribution provides an even worse fit (p-value of $10^{-9}$). Tests against more FRBs in the $z > 0.5$ range, where the models differ, and extensions of the models to account for e.g. host
metallicity, may help to resolve these uncertainties in the FRB host distribution.
Read the full abstract ▾
All authors C. W. James, N. Loudas, M. Woodland, B. C. Andersen, J. X. Prochaska, J.L. Hoffmann, L. Marnoch, S. D. Ryder
High Energy Astrophysical Phenomena
Circular polarization effects induced by photon-axion mixing in astrophysical environments
Meng Wang, Nan Ding, Qiusheng Gu et al. (+2 more)
Axions and
axion-like particles (ALPs) are compelling candidates for dark matter and new physics beyond the Standard Model.
Photon-
axion mixing in external
magnetic fields modifies the
photon energy spectrum and linear polarization state, and also induces circular polarization signals. Compared to spectral and linear polarization methods, circular polarization benefits from lower astrophysical background contamination, providing an independent probe for
axion searches. In this work, we study the circular polarization induced by
photon-
axion mixing within the
chiral basis framework. By analytically solving the
evolution equations under the single-domain approximation, we derive an expression for the circular polarization degree $P_C$, applicable in the resonant, strong coupling, and weak coupling regimes. Within single-domain
magnetic field models, we compare the energy-dependent circular polarization in four astrophysical environments (AGN jets, intracluster medium, intergalactic medium, and
Galactic magnetic fields). We find that the X-ray to MeV band represents the most sensitive observational window. Using the blazar S4 0954+65 as a case study, phase accumulation in random
magnetic domains causes the circular polarization degree to fluctuate with
redshift and exhibit pronounced energy structures. Using the optical circular polarization upper limit $P_C < 0.184\%$ (measured in the z-SDSS band) from this source, we statistically constrain $g_{a\gamma\gamma} \lesssim 3\times 10^{-11}\,\mathrm{GeV}^{-1}$ (95% confidence level) for $m_a \sim 10^{-16}$–$10^{-10}\ \mathrm{eV}$, with the strongest constraint reaching $g_{a\gamma\gamma}\sim6\times10^{-12}\,\mathrm{GeV}^{-1}$ near $m_a \sim 10^{-14}\,\mathrm{eV}$. These results establish circular polarization as a complementary
axion probe.
Read the full abstract ▾
All authors Meng Wang, Nan Ding, Qiusheng Gu, Yunyong Tang, Rui Xue
High Energy Astrophysical Phenomena
Gamma-Ray Emission from the Crab Pulsar: A 17-Year Fermi-LAT Reanalysis
Liancheng Zhou, Yun-Lu Gong, Jun Fang et al. (+1 more)
We present a reanalysis of 17 years of
Fermi Large Area
Telescope (LAT) observations of the Crab
pulsar obtained between 2008 August and 2025 August. Using monthly Jodrell Bank
radio ephemerides, we assigned pulse phases to the LAT events and aligned the phase zero across the full data set. From this phase-aligned data set, we derived pulse profiles over 100 MeV to 300 GeV. The pulsed emission remains clearly detectable in the 10 to 20 GeV and 20 to 30 GeV bands, with H-test significances of 32.36 sigma and 11.59 sigma, respectively, but is not significantly detected in the 30 to 300 GeV band. Phase-resolved likelihood analysis was performed over 100 MeV to 30 GeV using 14 phase bins with comparable pulsed statistics. The fixed-window fractional fluxes show that the contribution of Peak 1 (P1) decreases steadily with energy, while those of Peak 2 (P2) and the Bridge increase, with P2 exceeding P1 above 10 GeV. Finally, the same phase-assignment framework also enables an off-pulse analysis from 100 MeV to 1 TeV, confirming the synchrotron and inverse-Compton components that dominate the emission in the selected off-pulse interval.
Read the full abstract ▾
All authors Liancheng Zhou, Yun-Lu Gong, Jun Fang, Li Zhang
Solar and Stellar Astrophysics
Turbulent Diffusion of Magnetic Field Lines in the Heliosphere
J.V.A. Joubert, R.D. Strauss, J. Light et al. (+2 more)
Due to
solar wind
turbulence, Parker spirals are
stochastic. The dispersion of
magnetic field lines is described by a convection-
diffusion equation for the field line density distribution which is a function of the two heliographic angles in addition to the radial distance. Taking into account the radial
evolution of the
turbulence, the three-dimensional convection-
diffusion equation is transformed into a set {of}
stochastic differential equations which is solved numerically using both a forward and backward formulation. By tracing a large number of
stochastic Parker spirals, the field line density distribution is constructed at any point in the heliosphere. It is shown that the angular part of the distribution function can be well-fitted by a two-dimensional Gaussian with standard deviation close to $ 25^{\circ}$ at 1 AU. The simulations also confirm that the
magnetic field lines are underwound, on average, for strong enough
turbulence intensity. Applying the backward approach,
magnetic field lines are traced from an observer at 1 AU back to the Sun, quantifying the probability of
magnetic connection when interplanetary
turbulence is accounted for. It is shown that the angular uncertainty of $\sim 25^{\circ}$ is sharply reduced to $\sim 4^{\circ}$ when the field lines are traced back to the
solar wind source surface from 0.25 AU.
Read the full abstract ▾
All authors J.V.A. Joubert, R.D. Strauss, J. Light, N.E. Engelbrecht, N.H. Bian
Solar and Stellar Astrophysics
Phase-drifting with emitting plasma temperature in the quasi-periodic pulsations of an X-class solar flare
Libo Fu, Valery M. Nakariakov, Ding Yuan et al. (+3 more)
Recent multi-wavelength observations of
solar flares have provided new constraints on the physical origin of quasi-periodic pulsations (QPPs). In an X-class
flare, we detect a short-lived $\sim$5-minute QPP simultaneously in hard X-rays, extreme-ultraviolet (EUV), and soft X-ray emissions, exhibiting a clear phase-drifting behavior with emitting
plasma temperature. Based on phase-resolved timing analysis, it is found that (i) the QPPs in all diagnostics share nearly identical oscillation periods, (ii) a systematic temperature-dependent phase drifting is present, with the phase delay relative to the hard X-ray emission increases systematically from the hottest to cooler EUV channels, and (iii) the QPP persists for only a few cycles during the impulsive phase. These properties imply that periodic
magnetic reconnection, possibly triggered by the leakage of 5-minute oscillations from the lower atmosphere, modulates the non-thermal electrons responsible for the leading Hard X-ray QPPs. Subsequently,
plasma heating and cooling processes manifest sequentially across passbands with different temperature responses, resulting in the observed temperature-dependent phase drifting. These results provide novel observational evidence supporting the use of multi-temperature, multi-wavelength phase relationships to constrain the temporal
evolution of
flare energy release and the origins of QPPs.
Read the full abstract ▾
All authors Libo Fu, Valery M. Nakariakov, Ding Yuan, Suraj Sahu, Song Feng, Ehsan Tavabi
Solar and Stellar Astrophysics
Solar flare ribbons structured by uncombed chromospheric loops
L. P. Chitta, E. R. Priest, David Orozco Suárez et al. (+33 more)
A part of the
magnetic energy released during a
flare is transported to the lower atmosphere. High-resolution observations show that
flare ribbons, sites of energy deposition at the footpoints of flaring loops which appear bright in the chromosphere and transition region, are structured on small spatial scales on the order of 100 km. Based on idealized numerical models of
flares it is suggested that the ribbon fine-structures could originate from a tearing instability and the development of plasmoids in current sheets. Here we report on Fe I 5250.6 Å and Mg I b2 5173 Å spectral observations of a
solar flare from the Tunable Magnetograph onboard the SUNRISE III balloon-borne mission that reveal an intricate link between the
flare ribbon structure and the ambient chromosphere. We identified uncombed chromospheric loops and non-flaring fine-structures that are interspersed among brighter
flare ribbon threads. These loops remain stable on timescales of minutes. Spectral lines from these regions show reduced emission or self-reversal in the line core compared with the immediately adjacent
flare ribbons. We discuss the potential role of these structures in the onset of a
flare. Furthermore, we suggest that irrespective of the complexities in the flaring current sheet, uncombed chromospheric loops and nonflaring fine-structure might play a role in spatially modulating the
flare energy deposition in the lower atmosphere.
Read the full abstract ▾
All authors L. P. Chitta, E. R. Priest, David Orozco Suárez, Azaymi L. Siu-Tapia, Jose Carlos del Toro Iniesta, Francisco Javier Bailén, Julian Blanco Rodríguez, Alberto Álvarez-Herrero, Maria Balaguer Jiménez, Esteban Sanchis Kilders, Ignacio Torralbo, Christoph Kuckein, Sami K. Solanki, Andreas Lagg, Achim Gandorfer, Yukio Katsukawa, Pietro Bernasconi, Thomas Berkefeld, Alex Feller, Tino L. Riethmüller, Masahito Kubo, H. N. Smitha, Bianca Grauf, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Juan Sebastián Castellanos Durán, Edvarda Harnes, Johannes Hoelken, Francisco A. Iglesias, Ryohtaroh T. Ishikawa, Yusuke Kawabata, Takuma Matsumoto, Takayoshi Oba, Hanna Strecker, Dušan Vukadinović
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Natural Inflation with a negative cosmological constant
Chia-Min Lin, Naoto Maki and Kazunori Kohri
In this work, we investigate a
cosmic inflation model based on a cosine-type potential with a negative cosmological constant. This model originates from a classical solution of the Wheeler-DeWitt equation. The equation of motion for the inflaton field can be solved analytically without relying on approximation schemes, such as the slow-roll conditions. The predictions of the spectral index, the tensor-to-scalar ratio, and the running spectral index are calculated and compared with experimental constraints from Planck Collaboration, Atacama Cosmology
Telescope Collaboration (ACT), and Dark Energy Spectroscopic Instrument (DESI).
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
The dynamics of the Anglerfish cluster
B. Destefanis, M. Balboni, I. Bartalucci et al. (+8 more)
Merging
galaxy clusters represent the ideal laboratory to test our understanding of the large scale structure formation history and the processes involved. While many merging clusters have been identified, only a limited number have been studied in detail through multi-wavelength analysis and dynamical reconstruction, this type of analysis being crucial to account for projection degeneracies. This work investigates the merger dynamics of the massive and complex cluster MACS0600 using high spatial, $\sim 15$ arcsec,
radio and X-ray
datasets in combination with ancillary optical data. We analyze the cluster morphology and the thermodynamic properties of the intracluster medium (ICM) through XMM-Newton and Chandra X-ray observations, and explore the non-thermal component via diffuse
radio emission observed with Meerkat. We find a disturbed X-ray morphology with multiple substructures and a clear offset between the bulk of the
radio emission and the X-ray peak. At the location of the X-ray peak, we detect a compact cool core surrounded by hotter gas and associated with a surface brightness discontinuity consistent with a cold front. The central region exhibits elevated temperatures and hosts most of the diffuse
radio emission, suggesting merger-driven
turbulence. Optical data further support a relative motion between the cool core and the main cluster along the line of sight. We conclude that MACS0600 is undergoing a merger in which a compact cool core has crossed the main, more massive cluster without being completely disrupted, while significantly perturbing the surrounding ICM.
Read the full abstract ▾
All authors B. Destefanis, M. Balboni, I. Bartalucci, M. Annunziatella, F. Gastaldello, S. De Grandi, S. Ghizzardi, C. Grillo, L. Lovisari, S. Molendi, M. Rossetti
Astrophysics of Galaxies
The Quasar Main Sequence of Super-Eddington NLSy1 Galaxies
Alberto Domínguez, Suvendu Rakshit, Vaidehi S. Paliya et al. (+2 more)
The
quasar main sequence, or Eigenvector 1 (EV1), describes the optical diversity of active
galactic nuclei (AGN), with Narrow-Line Seyfert 1 (NLSy1)
galaxies anchoring the high-
accretion end. Recent discoveries of overly massive black holes in the early Universe highlight the need to study low-
redshift, low-mass super-Eddington accretors as analogs of rapid black hole growth. We map a population of 18,749 NLSy1
galaxies identified in the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1) onto the EV1 plane to determine whether they represent a distinct population of super-accretors. We compare the spectral properties of the DESI DR1 NLSy1 sample with the SDSS DR17 NLSy1 catalog. We extract key parameters, including the broad H-beta full width at half maximum (FWHM) and Fe II strength (R4570). To evaluate their
accretion states, we derive single-epoch virial black hole masses using an Fe II strength-dependent scaling relation and an Eddington rate-dependent fundamental plane, both of which confirm their high
accretion rates. The DESI DR1 NLSy1 population shows a consistent shift toward the extreme end of the EV1 parameter space, possessing strong Fe II emission (median R4570 = 0.97 +/- 0.36), similar to the SDSS sample (median R4570 = 0.97 +/- 0.34). Furthermore, considering both calibrations, DESI and SDSS sources harbor low-mass black holes (median log black hole mass ~6.81-6.85). About 50% of the NLSy1
galaxies exhibit super-Eddington
accretion (log Eddington ratio > 0). The unprecedented sensitivity of DESI has unveiled a large population of low-mass, super-Eddington accreting sources. These intriguing EV1 objects struggle to process luminous
accretion flows, naturally producing the observed intense Fe II emission. This unique sample provides a rich statistical
dataset of low-
redshift super-Eddington accretors for understanding early-Universe black hole growth.
Read the full abstract ▾
All authors Alberto Domínguez, Suvendu Rakshit, Vaidehi S. Paliya, D. J. Saikia, C. S. Stalin
Astrophysics of Galaxies
Narrow-Line Seyfert 1 Galaxies in the Dark Energy Spectroscopic Instrument Data Release 1
Vaidehi S. Paliya, Suvendu Rakshit, Alberto Dominguez et al. (+2 more)
Narrow-line Seyfert 1 (NLSy1)
galaxies are peculiar active
galactic nuclei (AGN) known to exhibit a variety of intriguing observational features from low-frequency
radio waves to high-energy $\gamma$~rays. As of now, NLSy1 catalogs are primarily based on optical spectroscopic observations from the Sloan Digital Sky Survey (SDSS). Here we report, for the first time, a new catalog of NLSy1
galaxies using the high-quality optical spectroscopic observations made public in the first data release of the Dark Energy Spectroscopic Instrument (DESI). We performed a detailed spectral decomposition of more than 71,000 optical spectra of AGN not included in the SDSS catalog and located at $z<0.9$. From this sample, we identify 18749 objects as NLSy1
galaxies for the first time. We also supplement the NLSy1 catalog with a sample of broad-line Seyfert 1
galaxies. The NLSy1
galaxies identified in the DESI data tend to have slightly higher bolometric luminosities and lower black hole masses (though with large dispersions), leading to the higher Eddington ratios than those of the SDSS-NLSy1 sample matched in
redshifts and absolute $B$-band magnitudes. Moreover, the fraction of DESI-NLSy1
galaxies detected in the
radio, X-ray, and $\gamma$-ray catalogs was found to be lower than that of SDSS-NLSy1 sources. We conclude that deeper multiwavelength investigations of these enigmatic AGN will help unravel the low-luminosity end of the NLSy1 population. The catalog has been made available at https://www.ucm.es/blazars/seyfert and Zenodo https://doi.org/10.5281/zenodo.20484681.
Read the full abstract ▾
All authors Vaidehi S. Paliya, Suvendu Rakshit, Alberto Dominguez, D. J. Saikia, C. S. Stalin