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Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 1 July

Solar and Stellar Astrophysics

Stellar Forcing of (exo)Planetary Environments

Julián D. Alvarado-Gómez, Erika Palmerio, Manuel Güdel et al. (+13 more)

The environments of exoplanets are fundamentally shaped by the magnetic activity of their host stars through radiative, plasma, and particle-driven processes. This article presents a comprehensive overview of the four principal forms of stellar forcing that regulate atmospheric structure, chemistry, escape, and long-term planetary evolution: high-energy radiation, magnetized stellar winds, coronal mass ejections, and energetic particles. Using the Sun as a physically resolved benchmark, the discussion extends to increasingly active cool stars to establish a broader picture of star–planet interactions across the main sequence. The article first examines stellar X-ray and extreme ultraviolet emission from chromospheres and coronae, together with variability introduced by flares and magnetic reconnection. Particular attention is given to spectroscopic diagnostics, activity scalings with stellar rotation and age, flare energetics, and the observational links between impulsive and gradual phases of magnetic energy release. The treatment then shifts to magnetized stellar winds, describing the mechanisms that drive them and the role of multidimensional magnetohydrodynamic modeling in determining wind structure, angular momentum loss, and planetary interaction regimes. Solar and stellar coronal mass ejections are explored through their diagnostics, flare associations, propagation, and possible suppression by strong stellar magnetic fields. Finally, galactic and stellar energetic particles are discussed together with methods for estimating particle environments and their consequences for atmospheric chemistry and climate. The article concludes by outlining future observational and numerical developments needed to connect these coupled stellar forcing processes within a unified exoplanetary framework.
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All authors Julián D. Alvarado-Gómez, Erika Palmerio, Manuel Güdel, Kosuke Namekata, Konstantin Herbst, N. Eugene Engelbrecht, Antoine Strugarek, Judy J. Chebly, Astrid Veronig, Maria D. Kazachenko, Krisztián Vida, Kristina G. Kislyakova, Katja Poppenhäger, Antonio García-Muñoz, Yuta Notsu, Harish K. Vedantham

Astrophysics of Galaxies

Searching for the elusive CH2+ with the James Webb Space Telescope. Another carbocation to constrain astrochemical networks

M. Zannese, L. H. Coudert, E. Dartois et al. (+14 more)

Carbocations are key species in interstellar chemistry, providing entry points for building larger hydrocarbons. CH+, and more recently, CH3+, have been detected. Other carbocations await detection to provide a comprehensive view of the astrochemical network that is at work in the interstellar medium. We search for CH2+ in objects in which CH3+ was detected and evaluate the most favorable conditions for detecting the elusive CH2+ reactive cation. We calculated the CH2+ rotational and rovibrational transitions expected to contribute in the mid- to far-infrared, focusing on the lower-energy rovibrational levels. We then calculated CH2+ infrared emission spectra at different excitation temperatures and compared them to JWST spectra of the externally irradiated disk d203-506 in Orion, where CH+ and CH3+ have already been detected. We used thermochemical models to predict the abundance and spatial morphology of CH2+ to better understand its nondetection. The comparison to JWST spectra allowed us to provide excitation-temperature-dependent upper limits to the excited column density. These are several times lower than those detected for CH+ and CH3+ in their excited states. Based on model calculations for photodissociation regions and assuming similar excitation temperatures, the upper limit derived from observations and CH2+ model spectrum is either slightly above or below the column density expected from models of photodissociation regions. We provide a list of tabulated transitions to allow the community to search for this carbocation in future observations as CH2+ is key in providing observational constraints on astrochemical models.
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All authors M. Zannese, L. H. Coudert, E. Dartois, P. Dell'Ova, O. Roncero, P. del Mazo-Sevillano, U. Jacovella, B. Gans, J. R. Goicoechea, D. Van De Putte, C. Boersma, E. Habart, E. Peeters, J. Cami, R. Chown, I. Schroetter, O. Kannavou

Instrumentation and Methods for Astrophysics

WST, the wide-field spectroscopic telescope: progress on the design of the instruments

David Lee, Joel Vernet, Elizabeth George et al. (+46 more)

WST, the Wide-field Spectroscopic Telescope is a proposed new facility that will provide a transformational gain in spectroscopic survey capability over existing facilities. The WST is a 12 metre class telescope equipped with instrumentation to provide simultaneous observations in both multiple-object spectroscopy and integral field spectroscopy modes. This paper will describe the status of the instruments being designed for the WST, the fibre positioner module, the low and high-resolution multiple object spectrographs, the integral field spectrograph, disperser technology, sustainable detector and cryostat technology, and the calibration system. An overview of the overall layout of the instruments within the WST facility will be provided.
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All authors David Lee, Joel Vernet, Elizabeth George, Omar Sqalli, Olaf Iwert, Alessandro Meoli, Vincenzo Mainieri, Philippe Dierickx, Alexandre Jeanneau, Corentin Cudennec, Paolo Franzetti, Olga Bellido, Roelof de Jong, Andreas Kelz, Aaron Omadutt, Steve Watson, Younes Chahid, Chris Waring, Laura Gibbs, Anmol Goyal, Dave Melotte, Lawrence Bissell, Jay Stephan, Oscar Gonzalaez, Sebastien Pernecker, Maxime Rombach, Malak Galal, Jonathan Wei, Jean-Paul Kneib, Joseph W. Barrow, Jon Lawrence, Will Saunders, Dimitri Buffat, Kjetil Dohlen, Andrea Tozzi, Anna Brucalassi, Simone DAuria, Sofia Randich, Matteo Munari, Andrea Bianco, Christophe Yeche, Christophe Magneville, Etienne Burtin, Thomas Augusteijn, Jan Kragt, Ramon Navarro, Julia Bryant, Laurane Freour, Roland Bacon

Instrumentation and Methods for Astrophysics

WST, the Wide-field Spectroscopic Telescope: Telescope structure FE analyses

Simone D'Auria, Vincenzo Cianniello, Ciro Del Vecchio et al. (+6 more)

The Altitude Structure of the Wide-field Spectroscopic Telescope (WST) is designed to support and position both primary and secondary mirrors, made of structural steel. Due to its dimensions, the Altitude Structure is a substantial part of the WST facility, and its weight, performance, and dynamic behavior play a critical role in the functioning of the Telescope. This paper discusses the iterative process starting from the preliminary structural layout and leading to the optimization of the entire Structure. A Finite Element (FE) model was developed, defining the detailed dimensions and cross sections of each assembly's beams and plates under representative boundary conditions, in order to correctly simulate the operational environment. This model enables accurate estimation of structural weight, mechanical deformations, and stresses, as well as its frequency response for the evaluation of both local and global resonance modes. Based on the initial results obtained using preliminary beam cross sections and shell thickness, several assumptions were formulated to drive the mechanical optimization of the Altitude Structure. The outcome of this work consists of a refined structural configuration and the formulation of the governing design criteria.
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All authors Simone D'Auria, Vincenzo Cianniello, Ciro Del Vecchio, Vincenzo De Caprio, Philippe Dierickx, Gaston Gausachs, Tony Trauvillon, William Sutherland, Olga Bellido

Instrumentation and Methods for Astrophysics

WST, the Wide-field Spectroscopic Telescope: Mechanical Design and FE Analyses for the High Resolution Spectrograph

Simone D'Auria, Andrea Tozzi, Anna Brucalassi et al. (+5 more)

The Wide-field Spectroscopic Telescope (WST) is a planned 12-meter-class dedicated spectroscopic facility designed to address key scientific challenges through large spectroscopic surveys. This paper presents the current status of Work Package 4.5, which focuses on the High-Resolution Multi-Object Spectrograph (MOS-HR) module for WST. The MOSHR instrument is expected to provide a resolving power of R = 40,000 with a multiplexing capability of about 2,000 targets. The mechanical design activities carried out for the development of the HR spectrograph and for the definition of its optomechanical architecture are described. To account for both the scientific requirements of the spectrograph and the manufacturability constraints associated with such a complex instrument, the mechanical layout has been organized into four larger modules, each containing two sub-modules. Guided by feasibility considerations, such as mechanical performance, available volume, and fabrication and assembly aspects, each sub-module adopts a vertical optical bench configuration with optical elements mounted on both sides. Starting from the baseline optical design, the mechanical configuration has been developed to achieve the required alignment accuracy, structural stability, and environmental robustness. The workflow includes the translation of the optical prescription into a complete mechanical model, the definition of the main mounting and alignment interfaces, and preliminary static, modal, and seismic analyses to evaluate performance under operational and survival loads. As an outcome, the proposed design provides architecture that enables preliminary estimates of mass, volume, cost, and mechanical performance in terms of deformation, stress, and modal behavior of the modules.
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All authors Simone D'Auria, Andrea Tozzi, Anna Brucalassi, Matteo Munari, Ciro Del Vecchio, Maria Sofia Randich, Roland Bacon, David Lee

Astrophysics of Galaxies

Tilting at the Turnover: Modeling the Faint-End of the UV Luminosity Function Behind Abell s1063 with JWST

Caio Moreira Goolsby, Christopher J. Conselice, Duncan Austin et al. (+6 more)

We leverage the strong gravitational field of Abell S1063 to identify faint, highly magnified galaxies using ultra-deep James Webb Space Telescope (JWST)/NIRCam imaging from the GLIMPSE survey and ancillary Hubble Space Telescope (HST)/ACS imaging from the Hubble Frontier Fields program. We construct a photometric catalogue of lensed high-redshift candidates and use these sources to constrain the faint end of the rest-frame UV luminosity function (UVLF) over $z\simeq6$–11. Rather than treating the UVLF turnover ($M_{\rm t}$) as a hard cutoff, we model it as a gradual quadratic suppression and explicitly account for the potential continued contribution of galaxies beyond the turnover. In a shallow-turnover scenario, up to one-third of the UV luminosity density can arise from sources fainter than $M_{\rm t}$. While we find no direct evidence for a turnover down to $M_{\rm UV}=-13.5$ at $z=6$, our analysis can only confidently exclude weak, medium, and strong turnover models down to $M_{\rm t}=-15.9$, $-15.1$, and $-14.8$, respectively. Across these models, we infer lower limits of the UV luminosity, star formation density, and the ionization rate as: $\rho_{\rm UV}\geq22\times10^{25}\,{\rm erg\,s^{-1}\,Hz^{-1}\,Mpc^{-3}}$, ${\rm SFRD}\geq25\times10^{-3}\,M_\odot\,{\rm yr^{-1}\,Mpc^{-3}}$, and $\log_{10}(\dot{n}_{\rm ion}/{\rm s^{-1}\,Mpc^{-3}})\geq51.02$. We find that galaxies fainter than the conventional $M_{\rm UV}=-17$ limit contribute more than half of the UV luminosity density and at least $\sim64\%$ of the ionizing photons produced by star-forming galaxies at $z=6$. Because our turnover model permits a suppressed, but non-zero, galaxy population beyond $M_{\rm t}$, sources fainter than the turnover remain contributors to both $\rho_{\rm UV}$ and $\dot{n}_{\rm ion}$, emphasizing the need to consider the turnover and its shape during reionization.
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All authors Caio Moreira Goolsby, Christopher J. Conselice, Duncan Austin, Tom Harvey, Jose Diego, Nathan Adams, Julien Marabotto, Jordan D'Silva, Qiong Li

High Energy Astrophysical Phenomena

Smoking-gun evidence for hierarchical black-hole mergers

Yin-Jie Li, Yuan-Zhu Wang, Shao-Peng Tang et al. (+1 more)

How stellar-mass black holes grow after their birth is a central open question in astrophysics. Gravitational-wave observations have revealed a subpopulation of coalescing black holes with both high masses and high spins, but whether these properties arise from hierarchical mergers in dense stellar environments or from accretion onto isolated black holes has remained unresolved. Here, using a flexible mixture population model applied to the 259 binary black hole mergers in GWTC-5, we show that the mass function of the high-spin subpopulation traces, peak by peak, the predicted remnant-mass distribution of the low-spin, stellar-collapse-origin subpopulation up to $\sim80\,M_\odot$. This morphological match, quantified by a Bhattacharyya coefficient as high as $\sim0.95$, is naturally expected if the high-spin black holes are themselves the products of earlier mergers, whereas any alternative scenario would require fine-tuning, thereby providing smoking-gun evidence for hierarchical mergers. In addition, the sharp upper-mass cutoff of the low-spin subpopulation at $m_{\rm max,1}=54.2^{+7.7}_{-7.2}\,M_\odot$ yields an astrophysical $S$-factor of $S_{300}=151^{+30}_{-26}$~keV~b (68% credible interval) for the $^{12}{\rm C}(\alpha,\gamma)^{16}{\rm O}$ reaction, in agreement with the benchmark theoretical value. These results establish that the entire observed black-hole population can be accounted for by stellar collapse followed by dynamical hierarchical assembly, without invoking primordial black holes.
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All authors Yin-Jie Li, Yuan-Zhu Wang, Shao-Peng Tang, Yi-Zhong Fan

Solar and Stellar Astrophysics

Automatic detection of solar filament oscillations I: Multi-scale spectral pipeline

Guillem Castelló, Manuel Luna and Jaume Terradas

Solar filament oscillations provide important diagnostics of prominence magnetic structure and stability, but their detection in long H\alpha archives has traditionally relied on visual inspection, manually placed slits, and time–distance diagrams. We present an automatic pipeline for detecting spatially coherent filament oscillations in GONG H\alpha image sequences. The method combines image preprocessing and coalignment, deep-learning-based filament detection and segmentation, multi-scale spatial averaging, Lomb–Scargle spectral analysis, convolutional-neural-network background estimation, empirical calibration of significance thresholds, and clustering of candidate detections in period and space. Only oscillations supported across at least four spatial scales are retained, reducing sensitivity to local pixel-scale intensity fluctuations. The pipeline recovers several events from the manual GONG catalog of Luna et al. (2018), including the 1 January 2014 oscillation with a period of approximately 76 min. Applied to the first two weeks of January 2014, it identifies 91 oscillatory events, compared with 22 non-duplicate events in the corresponding manual catalog, with detected periods ranging from about 20 to 126 min. It also detects previously unreported oscillations, including an event on 13 January 2014 with a period of approximately 86 min that is independently confirmed using a conventional time–distance diagram. These results demonstrate that automated filament segmentation, multi-scale spectral analysis, and calibrated significance testing can provide a reproducible and scalable alternative to manual slit-based searches. The pipeline substantially increases detection sensitivity while preferentially selecting coherent filament-scale oscillations, enabling future statistical studies over extended GONG intervals and across the solar cycle.
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High Energy Astrophysical Phenomena

Early results from the SVOM Observatory Science program

A. Coleiro, L. Tao, F. Cangemi et al. (+44 more)

We present the organisation and early results from the Observatory Science program of the Space-based multi-band astronomical Variable Objects Monitor (SVOM), based on data collected between July 2024 and December 2025. Although primarily designed for gamma-ray burst studies, SVOM's wide-field, multi-wavelength instruments enable a broad range of high-energy astrophysical investigations. We summarize the execution and performance of the General Program and Target-of-Opportunity observations, and we describe the frameworks used for serendipitous source detection and monitoring with the ECLAIRs coded-mask instrument. Over this period, SVOM carried out more than a thousand pointed observations and detected several hundred non-GRB high-energy sources, mainly X-ray binaries, as well as blazars, stellar flares, magnetars, and unidentified events. We highlight some key results, including the monitoring of the microquasar Cygnus X-1, the detection of burst oscillations from the Low-Mass X-ray Binary 4U 0614+091, the spectral-state monitoring of Aql X-1, the first SVOM detection of an X-ray blazar flare from 1ES 1959+650, and observations of a stellar flare from HD 22468. These results demonstrate SVOM's strong capabilities for time-domain astrophysics beyond its core GRB program.
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All authors A. Coleiro, L. Tao, F. Cangemi, X. Han, M. Brunet, N. Dagoneau, A. Foisseau, A. Goldwurm, S. Guillot, N. Jiang, C. Lachaud, S. Le Stum, P. Maggi, D. Rawat, J. Rodriguez, C.W. Wang, J. Wang, W. Xie, L. Zhang, L. Bouchet, M. Clavel, Z. Feng, O. Godet, D. Götz, D. Li, Z. Li, L. Lin, T. Maiolino, J. Wu, L. Xin, S.L. Xiong, X. Xu, J. Zhang, S.J. Zheng, B. Cordier, J. Wei, S. Basa, A. Claret, F. Daigne, J. Deng, Y.W. Dong, E. W. Liang, Y. Qiu, S. Vergani, C. Wu, B. Zhang, S. N. Zhang

High Energy Astrophysical Phenomena

First Gamma-Ray Burst Observations with SVOM

F. Daigne, D. Turpin, J.-L. Atteia et al. (+34 more)

Following its launch on 22 June 2024, the Space-based multi-band astronomical Variable Objects Monitor (SVOM) successfully completed its flight acceptance, commissioning, and scientific validation phases in early 2025, during which several tens of gamma-ray bursts (GRBs) were detected onboard. Three quarters of these events have also been detected by other satellites, and a quarter are SVOM-only GRBs. In this article, we describe these early GRB observations, with a first description of the SVOM GRB sample that is emerging, and of the level of characterisation already achieved, and with a focus on a few events of particular interest. These early results are very encouraging regarding SVOM's ability to detect and fully characterise (including prompt emission, afterglow and distance) a wide range of GRBs (classical long GRBs, short GRBs, X-Ray Flashes, etc.) and to enable the use of these extreme high-energy transients as probes of the distant Universe.
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All authors F. Daigne, D. Turpin, J.-L. Atteia, J. Palmerio, L.-P. Xin, S. D. Vergani, B. Zhang, C. Wu, T. Maiolino, B. Schneider, D. Zhao, A. Li, D. Malesani, H.-L. Li, A. Saccardi, M.-G. Bernardini, H. Gao, F. Piron, O. Godet, B.-B. Zhang, Y. Wang, L.-J. Chen, B. Cordier, J.-Y. Wei, S. Basa, A. Claret, A. Coleiro, J.-S. Deng, Y.-W. Dong, D. Götz, X.-H. Han, Y.-L. Qiu, C. Lachaud, E.-W. Liang, J. Wang, S.-L. Xiong, S.-N. Zhang

High Energy Astrophysical Phenomena

Bridging the gap between SLSNe and SE-SNe. Multi-wavelength analysis of the SLSN-Ib SN 2024jlc

A. Simongini, F. Acero, M. Imbrogno et al. (+15 more)

The Type I super-luminous supernova SN~2024jlc (ZTF24aapadbb) exploded on the 25th of May 2024 at $z = 0.039$. Being the closest supernova of this class discovered in recent years and one of the closest ever, represented a rare opportunity to study in detail this type of objects. We performed a multi-wavelength analysis, spanning ten orders of magnitude in frequency, including optical/UV photometry and spectroscopy, soft and hard X-rays, and high-energy $\gamma$-rays. We characterized the event as a slow-evolving and He-rich supernova, with one of the lowest peak luminosities reported for a super-luminous event $M_g\sim-19.37$ mag, and a light curve evolution compatible with both circumstellar interaction and magnetar spin-down models, with noticeable contribution from $^{56}$Ni decay. No significant excess was found in the soft and hard X-ray bands, for which we provide upper-limits on the flux. Additionally, we analyzed two years of Fermi-LAT data, from which we report an intriguing hint of a $\gamma$-ray signal at the $\sim 3.6 \sigma$ level, although no firm detection can be claimed. The gamma to optical efficiency ratio, $\eta = 0.38$, is suggestive of the presence of a central-engine scenario, similar to SN~2017egm. Our analysis suggests that SN~2024jlc could bridge the gap between SLSNe and classical stripped-envelope supernovae. While still poorly populated, this bridge could consist of all SLSN-Ib supernovae, with the key difference residing in the powering mechanism.
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All authors A. Simongini, F. Acero, M. Imbrogno, J. L. Wise, J. Sollerman, S. Schulze, N. Paul M. Kuin, T. X. Chen, C. Fremling, A. Gangopadhyay, M. M. Kasliwal, R. R. Laher, Z. McGrath, D. A. Perley, J. N. Purdum, N. Rehemtulla, R. M. Rich, R. Riddle

Cosmology and Nongalactic Astrophysics

Foreground Characterization and Mitigation in the Observations of the CD/EoR with the SKA

Philip Bull, Jacob Burba, Emilio Ceccotti et al. (+20 more)

The Square Kilometre Array (SKA), with its unprecedented sensitivity, frequency coverage, and large collecting area, is poised to revolutionize our understanding of the Cosmic Dawn (CD) and Epoch of Reionization (EoR) epochs marking the formation of the first luminous sources and the subsequent reionization of the intergalactic medium (IGM). However, detecting the faint redshifted 21-cm signal from neutral hydrogen remains one of the foremost challenges in observational cosmology, as it is buried beneath bright foregrounds from Galactic synchrotron radiation, free-free emission, and extragalactic point sources that are 4-5 orders of magnitude stronger than the cosmological signal. In this chapter, we highlight the key components and characteristics of these foregrounds and review ongoing efforts to model, characterize, and mitigate them. We emphasize how the SKA-Low AA* configuration, through its optimized array design, wide field of view, and improved calibration accuracy, enhances our capacity to suppress foreground contamination and recover the cosmological signal. The SKA Observatory Foreground Challenge plays a pivotal role in this effort by bringing together the global EoR/CD community to develop, compare, and validate foreground removal pipelines using realistic simulated datasets. Building on the experience of existing pathfinders such as LOFAR, MWA, and HERA, these collaborative initiatives are helping refine statistical and machine learning-based approaches for signal recovery. Together, these advancements are laying the groundwork for the SKA to probe the thermal and ionization history of the early Universe with unprecedented precision.
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All authors Philip Bull, Jacob Burba, Emilio Ceccotti, Arnab Chakraborty, Samir Choudhuri, Abhirup Datta, Khandakar Md Asif Elahi, Sambit K. Giri, Takumi Ito, Vibor Jelic, Yi Mao, Florent Mertens, Satyapan Munshi, Ridhima Nunhokee, Andre R. Offringa, Samit Kumar Pal, Rashmi Sagar, Huanyuan Shan, Peter H. Sims, Emma Tolley, Anshuman Tripathi, Le Zhang, Zhenghao Zhu

Instrumentation and Methods for Astrophysics

Studying Ionosphere Using SKA-Low and SKA-Mid

Abhirup Datta, Samit Kumar Pal, Sarvesh Mangla et al. (+4 more)

The Earth's ionosphere introduces systematic effects that limit the performance of radio interferometers operating at low frequencies ($\lesssim 1$\,GHz). These ionospheric effects intensify during periods of heightened geomagnetic activity or for observations with extended baseline configurations. As each Pathfinder telescope operates at a different magnetic latitude, they experience distinct ionospheric regimes, offering complementary insights into ionospheric behaviour. In this work, we present a comparative study of ionospheric disturbances using observations from the uGMRT, VLA, MWA, and LOFAR, spanning a wide range of geographic and geomagnetic conditions. We present both antenna-based and field-based analyses to quantify phase fluctuations, positional offsets, and scintillation effects across these arrays. The measured total electron content (TEC) gradients reveal variations in spatial and temporal ionospheric structures with sensitivities that exceed those achievable with Global Navigation Satellite System (GNSS) measurements. By combining multi-telescope results, we assess the impact of ionospheric turbulence on calibration and imaging fidelity, and use these findings to forecast the expected ionospheric effects on observations with SKA-Low and SKA-Mid.
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All authors Abhirup Datta, Samit Kumar Pal, Sarvesh Mangla, Bhuvnesh Brawar, Sumanjit Chakraborty, Sudipta Sasmal, Anshuman Tripathi

Instrumentation and Methods for Astrophysics

Point spread function wavefront recovery from in-focus stellar observations

Ezequiel Centofanti, Samuel Farrens, Jean-Luc Starck et al. (+1 more)

Recovering the wavefront error (WFE) field of an optical system from intensity in-focus observations is a challenging inverse problem with broad implications for telescope point spread function (PSF) modelling. Accurate WFE recovery enables both precise PSF modelling and direct insight into the state of the telescope optics, facilitating the detection of potential malfunctions. Recently, non-parametric PSF models have shown promising performance in modelling complex optical systems in space-based telescopes. WaveDiff is a semi-parametric PSF model that represents the PSF in wavefront space by combining parametric and learnable features with a differentiable forward optical model. This parameterisation enables phase retrieval from in-focus observations by exploiting the spatial variation of the PSF across the field of view (FOV). The original version of WaveDiff achieves outstanding PSF recovery results in pixel space; however, the recovered WFE is far from the ground truth, with a relative error of around $30 \%$. In this paper, we present a new optimisation scenario that bridges WaveDiff's parametric and non-parametric components through wavefront feature projection, yielding a substantial improvement in WFE recovery and making WaveDiff the first demonstrated method to combine wide-field WFE recovery, in-focus-only polychromatic observations, and non-parametric wavefront features in a single framework. We show that incorporating wavefront projections and increasing the number of optimisation cycles enables WaveDiff to recover the WFE with an error of approximately $3 \%$ using only noisy, undersampled, in-focus observations. This represents a tenfold improvement over the original model while further reducing the pixel-space error. The code to reproduce the results of this article is publicly available at https://github.com/tobias-liaudat/wf-psf/tree/v1.4.0
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All authors Ezequiel Centofanti, Samuel Farrens, Jean-Luc Starck, Tobias Liaudat

Earth and Planetary Astrophysics

Understanding eccentric temperate giants: an in-depth study of the architecture and stellar obliquity of the TOI-2134 system

Federica Rescigno, Manu Stalport, Ancy Anna John et al. (+28 more)

We revisit the TOI-2134 planetary system with three new high-cadence TESS sectors and 98 more spectra. This new analysis confirms the two orbiting planets by simultaneously modelling a total of eight sectors of corrected TESS photometry and 280 HARPS-N and SOPHIE radial velocities: an inner mini-Neptune in a near-circular $9.229198\pm0.000003$ days orbit, and an outer temperate sub-Saturn orbiting with a $95.852840\pm0.000042$ days period and eccentricity of $0.31\pm0.01$. The masses and radii of the planets were computed to be $9.37\pm0.54$ Me and $2.735\pm0.068$ Re for planet b, and $58.3\pm1.9$ Me and $7.35\pm0.18$ Re for planet c. The new data not only improves the detection significance and precisions on the planetary orbits, but also breaks the original multimodality in the eccentricity solution for the outer planet. We also detect a long-term trend in the radial velocity data, which we attribute to a stellar magnetic cycle. We investigate the spin-orbit alignment of the system via observations of the Rossiter-McLaughlin effect for TOI-2134~b with EXPRES and TOI-2134~c with PARAS-2. No RM effect was detected for planet b, but we find a 4.7$\sigma$ detection of a $59\pm31^{\circ}$ obliquity for planet c. Finally, we examine the architecture of the system, assess its completeness, investigate the planetary interior, and their suitability for follow-up atmospheric analysis.
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All authors Federica Rescigno, Manu Stalport, Ancy Anna John, Tiger Lu, Daisy A. Turner, Lorena Acuña-Aguirre, Anand Bhongade, Anjali A.A. Piette, Vedad Kunovac, Michael Cretignier, Andrew Vanderburg, Ken Rice, Annelies Mortier, Rishikesh Sharma, Guillaume Hébrard, Abhijit Chakraborty, Alessandro Sozzetti, Andrew Collier Cameron, Pía Cortés-Zuleta, Rosario Cosentino, Florian Destriez, Mercedes López-Morales, Luca Malavolta, Jesús Maldonado, Giacomo Mantovan, Francesco Pepe, Matteo Pinamonti, André M. Silva, Stephane Udry, Shreyas Vissapragada, Thomas G. Wilson

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

Horizon-scale intensity and polarization images of rotating Konoplya-Zhidenko black holes with thick accretion flows

Bing-Bing Chen, Chen-Yu Yang, Guo-Ping Li et al. (+1 more)

We investigate the shadow and polarization images of a Konoplya–Zhidenko rotating non-Kerr black hole surrounded by a geometrically thick and optically thin accretion flow. The accretion flow is described by an analytical ballistic approximation accretion flow model. The numerical results show that the shadow image exhibits two main features, an outer bright ring and an inner dark region. The former corresponds to higher-order images, while the latter is associated with photon capture by the black hole. Increasing the deformation parameter $\eta$ does not significantly change the overall shape of the higher-order images, but it enlarges their size. Increasing either the spin parameter $a$ or the observer inclination angle $\theta_o$ enhances the asymmetry of the higher-order images and makes the intensity on the left side much larger than that on the right side. This behavior is associated with frame dragging and the relativistic Doppler effect. In the polarization images, the degree of linear polarization is much smaller in the higher-order image region than in other regions, and the polarization vectors extend over the whole image plane. Within the framework used in this work, these results illustrate how the spacetime geometry and near-horizon accretion dynamics jointly influence the intensity and polarization images.
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All authors Bing-Bing Chen, Chen-Yu Yang, Guo-Ping Li, Xin-Yun Hu

Astrophysics of Galaxies

Exploring the Milky Way stellar disk. Carbon, nitrogen, oxygen, sulphur, potassium, and copper abundances for 714 F- and G-type dwarf stars in the solar neighbourhood

Thomas Bensby

[ABRIDGED] We aim to determine abundances of carbon, nitrogen, sulphur, potassium, and copper for 714 nearby F and G dwarf and subgiant stars, and to re-derive oxygen abundances using updated corrections for departures from the assumption of local thermodynamic equilibrium. These elements extend the chemical inventory of our previous studies and provide new constraints on the relative enrichment histories of the Galactic thin and thick disks. The alpha-element behaviour of oxygen is confirmed, with old stars defining an enhanced sequence relative to young stars. Sulphur closely follows oxygen, while potassium shows broadly alpha-like behaviour in [K/Fe] but residual trends relative to oxygen. Carbon and nitrogen show only modest separation in [X/Fe], but much clearer population differences in [X/O]. Copper displays a strong metallicity dependence and clear separation between old and young populations when compared to oxygen. We also find that [O/Mg] is not constant, demonstrating that oxygen and magnesium provide complementary rather than interchangeable reference scales. Quantitative comparisons of all elements analysed in our studies show that carbon, oxygen, sulphur, and potassium rank among the most age-sensitive abundance ratios in the sample and provide strong discrimination between old and young disk populations. The new abundance measurements substantially expand the diagnostic power of this local stellar sample. The results show that abundance ratios relative to oxygen, together with precise stellar ages, reveal population differences that are partly hidden in traditional [X/Fe] trends. The expanded abundance inventory provides a homogeneous reference dataset for studies of Galactic chemical evolution, Galactic archaeology, and large spectroscopic surveys.
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Cosmology and Nongalactic Astrophysics

Strong Lensing Tomography: Double and pseudo multi-source plane strong gravitational lensing to constrain dark energy

Paras Sharma, Simon Birrer, Narayan Khadka et al. (+12 more)

Tomographic measurements of gravitational lensing with different lens and source redshift distributions contain crucial information about the universe's relative expansion rate, and hence dark energy. While this technique is well-established in weak lensing, its application to strong lensing has traditionally focused on Double Source Plane Lenses (DSPLs). However, DSPLs are exceedingly rare and fundamentally limited by the Mass-Sheet Degeneracy (MSD), a systematic uncertainty underexplored in previous literature. To overcome these challenges, we introduce Pseudo Double-Source Plane Lenses (PDSPLs): pairs of independent single-source plane lenses with self-similar deflectors. This generalizes the DSPL formalism to the $\sim 10^5$ galaxy-galaxy lenses expected from upcoming surveys like LSST, Euclid, and Roman. Unlike true DSPLs, PDSPLs are free from the intermediate source mass problem by construction, eliminating the associated secondary MSD and the need for multi-plane ray tracing. We incorporate the deflector galaxy's MSD into a hierarchical forecasting framework, demonstrating that this degeneracy severely degrades constraints from small DSPL samples, thus motivating our PDSPL statistical approach. We forecast constraints on the dark energy equation of state under a Flat $w_0w_a$CDM cosmology. The LSST 10-year photometric sample alone achieves $\sigma(w_0) \sim 0.45$, while simultaneously constraining the MSD parameter and deflector power-law slope to $\sim 2\%$. Adding a prior $\mathcal{N}(0.3, 0.05)$ on $\Omega_{\rm m}$ – simulating combination with external probes like CMB, BAO, or SNe Ia – tightens this to $\sigma(w_0) \sim 0.29$, competitive with current Stage III weak lensing analyses. Notably, this massive photometric sample outperforms smaller subsets with precise spectroscopic follow-up (e.g., from 4MOST), confirming statistical volume dominates over per-pair precision.
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All authors Paras Sharma, Simon Birrer, Narayan Khadka, Timo Anguita, Adam Bolton, Sydney Erickson, Phil Holloway, Tian Li, Phil Marshall, Dieu D. Nguyen, Graham P. Smith, Crescenzo Tortora, Bryce Wedig, the Strong Lensing Science Collaboration, the LSST Dark Energy Science Collaboration

High Energy Astrophysical Phenomena · Cross-listed from physics.atom-ph

Parts-per-million-accurate determination of the K${\alpha}$ photoionization resonance of Be-like oxygen with resolution of its $^{16}$O-$^{18}$O isotopic shift

Jonas Danisch, Marc Botz, Chintan Shah et al. (+15 more)

We determine with high accuracy the energy of the inner-shell transition $1s^2 2s^2~{}^1\mathrm{S}_0 \rightarrow 1s~2s^2~2p_{3/2}~{}^1\mathrm{P}_1$ ${}^{16}\mathrm{O}_{K\alpha}^{4+}$ at $554.372(3)~\mathrm{eV}$ ($\lambda$ = $22.36480(12)~\unicode{x212B}$) as well as its small shift of $2.2 \pm 1.3~\mathrm{meV}$ ($\Delta \lambda$ = $0.089(52)~\mathrm{m}\unicode{x212B}$) for the ${}^{18}\mathrm{O}$ isotope. This transition blends with a $K_\alpha$ line of $\mathrm{O}^{5+}$ used in astrophysical diagnostics, potentially affecting its reliability. In contrast to our experimental uncertainty of $\pm 3~\mathrm{meV}$, advanced electronic structure predictions for this four-electron system, including quantum electrodynamic (QED) corrections on the order of $100~\mathrm{meV}$, still scatter by more than $\pm 250~\mathrm{meV}$. Ions generated and stored in an electron beam ion trap were excited at the ELETTRA synchrotron facility with monochromatic soft x rays, with photon energies corrected by an additional spectrometer. Upon resonant excitation of $\mathrm{O}^{4+}$ and subsequent autoionization, we separate the photoions of each isotope by a time-of-flight measurement. This way, we resolve soft x-ray isotopic shifts of a few meV, obtain very accurate data on an essential astrophysical ion, and test calculations down to the level of QED contributions.
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All authors Jonas Danisch, Marc Botz, Chintan Shah, Moto Togawa, Joschka Goes, Dominic Hache, Filipe Grilo, Pedro Amaro, Vladimir A. Yerokhin, Steffen Kühn, Awad Mohamed, Roberta Totani, Monica de Simone, Stefano Orlando, Thomas Pfeifer, Fabrizio Nicastro, Marcello Coreno, José R. Crespo López-Urrutia

Astrophysics of Galaxies

Bar-driven secular evolution largely complete in a disk galaxy 7.6 billion years ago

Takafumi Tsukui, Zeyu Gao, Emily Wisnioski et al. (+4 more)

Disk galaxies like the Milky Way are thought to evolve through internal dynamical processes: the stellar disk forms a bar, the bar drives gas inflow that builds a nuclear stellar disk, and the bar vertically thickens into an X-shaped bulge. Although this evolution is thought to be slow, completing only at late cosmic times, its timing remains poorly constrained. We report James Webb Space Telescope imaging of a galaxy at redshift 0.92 (7.6 billion years ago) that already hosts an X-shaped bulge, a nuclear stellar disk, and an extended stellar disk, with geometry and inferred bar size indistinguishable from those of present-day barred galaxies. The X-shaped bulge marks the completion of the major phase of bar-driven evolution when the Universe was less than half its current age.
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All authors Takafumi Tsukui, Zeyu Gao, Emily Wisnioski, Joss Bland-Hawthorn, Satoru Iguchi, Themiya Nanayakkara, Karl Glazebrook

Astrophysics of Galaxies

The Milky Way Atlas for Linear Filaments III: Giant filaments and magnetic fields as evidence of a bubbly Galactic disk

Naval K. Bhadari, Ke Wang, Shu-ichiro Inutsuka et al. (+1 more)

Linear filamentary structures are fundamental constituents of the interstellar medium and play a central role in star formation. Their relative orientation with respect to the ambient magnetic field (B-field) provides key constraints on filament formation mechanisms. We investigate the relative orientation between Milky Way linear filaments (MWLFs) and the plane-of-sky B-field using polarization observations from the Atacama Cosmology Telescope (ACT) DR6, complemented by Planck data. Filament orientations are compared with the local B-field and the Galactic plane, while projection effects and statistical significance are quantified using Monte Carlo simulations of vector pairs in three-dimensions. We find no strong preferential alignment between MWLFs and the ambient B-field. Although the B-field is preferentially aligned with the Galactic plane with relative angles $\theta_{\rm BG} \sim0-25\deg$, filament orientations exhibit a bimodal distribution, being either parallel or perpendicular to the plane ($\theta_{\rm FG} \sim0-15\deg$ and $\sim75-90\deg$). Filaments located far from the Galactic midplane ($|z|>90$ pc) preferentially show perpendicular alignment with both the plane and the B-field, whereas those near the midplane exhibit a bimodal orientation. These results indicate that large-scale B-fields do not dominate the formation of MWLFs and instead favor a super-Alfvénic regime in which magnetic forces are dynamically subdominant, as expected for filaments associated with supernova-driven shells. Overall, our findings suggest that a face-on view of the Milky Way would resemble nearby disk galaxies such as M74, as observed in JWST images, with its disk structured by a network of supernova-driven bubbles (i.e., a bubbly disk).
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All authors Naval K. Bhadari, Ke Wang, Shu-ichiro Inutsuka, Mingke Sun

Earth and Planetary Astrophysics

Transmission Spectrum of the Benchmark Temperate Exo-Neptune TOI-1231 b

Subhajit Sarkar, Nikku Madhusudhan, Lorenzo Pica-Ciamarra et al. (+4 more)

The JWST is revolutionizing our understanding of the temperate sub-Neptune population through atmospheric spectroscopy. The nature of these planets remains debated, as their bulk properties are compatible with a range of interior scenarios, including mini-Neptunes, hycean worlds, and gas dwarfs, with different predicted atmospheric compositions. While theoretical studies have predicted compositional diagnostics for shallow- versus deep-atmosphere scenarios, there is a critical need for empirical constraints for a temperate planet that is a priori known to possess a deep H$_2$-rich atmosphere. The temperate exo-Neptune TOI-1231 b provides one such benchmark target. In this work, we present the JWST near-infrared (0.65–5.2 $\mu$m) transmission spectrum of TOI-1231 b, observed with NIRISS single-object slitless spectroscopy and NIRSpec G395H, representing the first for a temperate exo-Neptune. The density of TOI-1231 b requires a thick H$_2$-rich atmosphere, making the planet a keystone reference case for testing mini-Neptune scenarios for sub-Neptunes. We report a strong detection of CH$_4$ ($\ln B = 54.5$-$69.6$) and moderate to strong evidence for CO$_2$ ($\ln B = 2.9$-$6.6$). We do not find significant evidence for any other prominent molecule, although we find high 95% upper limits on the mixing ratios of NH$_3$ and CO, both of which are expected in deep H$_2$-rich atmospheres. We also do not find any significant evidence for sulfur-bearing species that have been inferred for some temperate sub-Neptunes. This composition is consistent with expectations for a temperate Neptune possessing a deep H$_2$-rich atmosphere with no distinct surface. We discuss the implications of our results for the characterization of temperate sub-Neptunes.
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All authors Subhajit Sarkar, Nikku Madhusudhan, Lorenzo Pica-Ciamarra, Måns Holmberg, Frances E. Rigby, Julianne I. Moses, Megan Mealing

Astrophysics of Galaxies

Projection-Enhanced Disk Breaks: Evidence from Deep Photometric Decomposition

Sergey S. Savchenko, Ilia V. Chugunov, Alexander A. Marchuk et al. (+5 more)

Radial brightness profiles of disk galaxies often exhibit so-called breaks – locations where their exponential-scale length abruptly changes. Some galaxies have downbending (Type II) breaks, where their brightness decays faster in outer regions, while other have upbending (Type III) breaks, resulting in more extended outer disks or envelopes. Disk radial profiles without any breaks (Type I) appear to constitute a minority. The exact fractions of different break types depend on many galactic parameters – such as Hubble type, stellar mass, spatial environment, and bar presence – and vary significantly across different studies. Another source of discrepancy is the orientation of galaxies: projection effects may play an important role in break detectability. In this work, we utilize DESI Legacy DR10 imaging to perform photometric decomposition of a sample of 375 edge-on galaxies and investigate their radial breaks. We find that the vast majority (~90%) of disks in our sample have Type II breaks, which is a considerably higher fraction than in many previous works (~50%). We carefully tested our results to check if observed breaks can be a result of flaring or two-disk composition. We showed that a high fraction of Type II breaks can be attributed to projection effects, which enhance the observed surface brightness of breaks in edge-on galaxies.
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All authors Sergey S. Savchenko, Ilia V. Chugunov, Alexander A. Marchuk, Vladimir P. Reshetnikov, Matvey D. Kozlov, Dmitry I. Makarov, Aleksandra V. Antipova, Anastasia M. Sypkova

Earth and Planetary Astrophysics

Native-resolution retrievals of VHS 1256-1257 b spanning the JWST/NIRSpec wavelength range: Chemical composition of a partially cloudy atmosphere

S. de Regt, N. Whiteford, B. E. Miles et al. (+3 more)

The wide wavelength coverage and sensitivity offered by JWST enable detailed analyses of extrasolar atmospheres. At its highest resolution (R~2700), NIRSpec measures the absorption from atomic, molecular, and isotopic gases whose abundances reflect the chemical composition of accreted material, making them key tracers of the formation environment. Orbiting an inner M-dwarf binary at a wide separation, the planetary-mass companion VHS 1256 b is one of the most variable sub-stellar objects known, with flux variations of 10-30%. We analyse the 0.97-5.27 micron NIRSpec ERS spectra of VHS 1256 b, update the data reduction and employ petitRADTRANS for atmospheric retrievals at the native spectral resolution. We model a partially cloudy atmosphere in chemical disequilibrium and fit directly for the elemental and isotopic abundances. Our best-fitting model closely matches the observations, bringing the residuals down to ~1%. The results are cautiously interpreted as degeneracies can bias some parameter constraints, most notably the mass and radius. Still, the retrieval finds a partial cloud deck covering ~79% of the visible surface, with a clearer column dominating at short wavelengths. Small changes of 1-3% can account for the high observed variability. From the many detected gases, we infer a metallicity, C/O ratio, and 12C/13C ratio in line with a solar composition, while the 18O isotope appears depleted relative to the Sun and local ISM. The isotope abundances are significantly lower than previous studies suggested, underlining the importance of our updated spectra. The 18O-depletion defies our understanding of the likely top-down formation. Our interpretation of the retrieved composition is complicated further by the lack of host star abundances. Nevertheless, this study demonstrates the value of panchromatic, native-resolution retrievals for characterising complex extrasolar atmospheres.
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All authors S. de Regt, N. Whiteford, B. E. Miles, S. Gandhi, D. González Picos, I. A. G. Snellen

Earth and Planetary Astrophysics

The Mid-Infrared Transmission Spectrum of the Temperate Sub-Neptune TOI-270 d

Måns Holmberg, Nikku Madhusudhan, Martin Binet et al. (+3 more)

Observations of temperate sub-Neptunes with JWST have ushered in a new era for atmospheric characterization of small exoplanets. In particular, the MIRI instrument provides a unique opportunity to search for molecules that are not easily accessible in the near-infrared, as demonstrated by recent mid-infrared observations of K2-18 b. In this work, we present the first mid-infrared transmission spectrum of TOI-270 d observed using the JWST MIRI LRS (5-12 $\mu$m) instrument. By leveraging archival MIRI LRS data, we establish a new empirical relation between the detector settling timescale and the flux, which helps accurately model the spectral light curves and improve the precision of the transmission spectrum. We find that there is notable evidence of molecular features in the MIRI transmission spectrum of TOI-270 d, favouring the presence of atmospheric absorption at $\ln B$ = 2.8-5.3 when comparing physically plausible atmospheric models with and without molecular line absorption. The data show excess absorption beyond what could be attributed to CH$_4$ and CO$_2$ detected previously, in line with recent near-infrared results. Through an agnostic search for 203 species, we identify several candidate trace molecules, most of which are complex molecules, evaluate their physical plausibility, and compare them against inferences from near-infrared observations. We also compare the MIRI spectrum of TOI-270 d to that of K2-18 b and find that random or systematic noise is unlikely to explain these observations. Future follow-up observations are necessary to definitively identify the additional absorbers beyond CH$_4$ and CO$_2$. These observations demonstrate the unique capability of JWST MIRI for atmospheric characterisation of temperate sub-Neptunes.
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All authors Måns Holmberg, Nikku Madhusudhan, Martin Binet, Subhajit Sarkar, Frances E. Rigby, Julianne I. Moses

Instrumentation and Methods for Astrophysics

The "dark dips" phenomenon in the LSST Camera on-sky images

Claire Juramy, Pierre Antilogus, Pierre Astier et al. (+4 more)

When the commissioning camera (ComCam), and then the LSST Camera, started taking on-sky images at the Vera Rubin Observatory, some of the ITL STA3800 CCDs exhibited a previously undocumented effect. When a sufficiently bright star is superimposed over the sky background, the sensor columns that contain the star appear slightly darker than the background, both above and below the position of the star. The visual appearance of these "dark dips" in the background is enhanced by a slight excess of flux within the neighboring columns, suggesting that they are caused by a lateral field distortion that shifts charges away from the central columns. This effect is not uniform across sensors, reaching an amplitude of up to seven percent of the background in the worst cases, but being undetectable in other sensors under the same conditions. For the affected sensors, the threshold required for the dips to become detectable also varies, from a few hundred to a few thousands saturated pixels within the star footprint. We developed means to quantify the dips, and studied the effect statistically over hundreds of frames, in order to categorize each sensor. In particular, we found no significant dependence on the filter color. We then developed a strategy to dynamically mask the affected columns during the Instrument Signature Removal process, to avoid any potential effect on photometric and astrometric performance.
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All authors Claire Juramy, Pierre Antilogus, Pierre Astier, John Banovetz, Sean Patrick MacBride, Andrew P. Rasmussen, Yousuke Utsumi

Astrophysics of Galaxies

Spatially resolved optical and mid-infrared spectroscopy of SDSS1335+0728: implications for the origin of the Ansky event

P. Sánchez-Sáez, M. Masterson, L. Hernández-García et al. (+25 more)

The galaxy SDSS1335+0728 brightened abruptly in December 2019 (the Ansky event) and has since been confirmed as the host of extreme X-ray quasi-periodic eruptions (QPEs) of debated origin. We constrain the origin of its transient activity by characterising the galaxy properties and nuclear accretion history with spatially resolved VLT/MUSE and JWST MIRI/MRS spectroscopy. We extract stellar and gas kinematics and emission-line fluxes, construct emission-line ionisation diagnostic maps, reconstruct the nuclear ionisation history via a Balmer-line light-echo analysis, and measure the mid-infrared silicate feature strength. The stellar kinematics reveal two counter-rotating stellar regions and kinematically cold gas ($\sigma_{\rm gas} \lesssim 60$ km s$^{-1}$), consistent with a past minor merger. Stellar populations show an old host with ongoing star formation confined to a ring at intermediate radii. Ionisation diagnostics reveal a three-zone structure: a central region powered by SMBH accretion, where high-ionisation coronal lines ([NeVI]$\lambda7.65\mu$m, [NeV]$\lambda14.32\mu$m, [OIV]$\lambda25.89\mu$m) are confined, a star-forming ring, and a LINER-like outer region. A Balmer-line light-echo analysis yields a minimum ionising luminosity $\log L_{\rm ion,min} \approx 40.5$ erg s$^{-1}$ sustained over at least $\sim 1\,500$ yr. Broad silicate emission at 9.7 and 18$\mu$m indicates optically thin dust, inconsistent with a classical active galactic nucleus (AGN) dusty torus. The data are consistent with two scenarios for the pre-2019 accretion: a persisting or gradually fading low-luminosity AGN, or a long-lived tidal disruption event (TDE) remnant disc. In both, Ansky corresponds to a slow, faint transient in a $\sim\!10^6\,M_{\odot}$ SMBH with already ongoing accretion, challenging the "faded AGN" interpretation proposed for some QPE hosts.
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All authors P. Sánchez-Sáez, M. Masterson, L. Hernández-García, R. Arcodia, P. Arévalo, F. Ávila-Vera, F. E. Bauer, J. Chakraborty, J. Cuadra, P. Lira, T. Wevers, R. J. Assef, A. Bayo, S. Bernal, R. Cartier, Y. Diaz, M. Giustini, H. Guo, D. Ilić, E. Kara, A. B. Kovačević, M.L. Martínez-Aldama, A. Merloni, G. Miniutti, C. Ricci, M. Sniegowska, G. Calistro Rivera, M. J. Graham

High Energy Astrophysical Phenomena

A self-consistent single-fluid framework for neutron stars admixed with mirror dark matter

Adamu Issifu, Constança Providência, Franciele M. da Silva et al. (+2 more)

We develop a self-consistent dark matter admix neutron star framework based on a contact vector current–current interaction that couples the chemical potentials of both sectors through mutual mean-field shifts, with the dark matter (DM) fraction $F_D = N_D/N_B$ fixed as a global input parameter. This formulation provides a physically motivated alternative to fixed-density prescriptions, allowing the local DM density to follow the baryonic matter (BM) density throughout the stellar interior. As an application, we consider a mirror-DM scenario with exact symmetry between the dark and visible sectors and investigate NS matter using the NL3$\omega\rho$, FSU2R, NL3, and DDME2 equations of state (EOSs). We find that the amount of DM introduced through $F_D$ weakens the binding of dense matter, reduces its incompressibility, and softens the EOS, while the DM–BM interaction governs the microscopic behavior of the DM in the dense BM medium. Consequently, DM increases the central density and compactness of NSs, lowers their maximum masses, and shifts the onset of the direct Urca process to higher stellar densities. As a consequence, the onset of rapid cooling is shifted to more massive stars for models with a stiff symmetry energy and to less massive stars for models with a soft symmetry energy, depending on the extra compactness that results from the DM admixture. These results demonstrate that mirror-DM admixtures modify both the microscopic composition and macroscopic structure of NSs, with potential implications for their thermal evolution and multimessenger observational signatures.
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All authors Adamu Issifu, Constança Providência, Franciele M. da Silva, Débora P. Menezes, Tobias Frederico

Astrophysics of Galaxies

Kolmogorov turbulence across multi-fractal gas in Polaris Flare

Xunchuan Liu, Pak-Shing Li and Yihuan Di

We reveal a pristine, scale-invariant 3D Kolmogorov velocity cascade ($\alpha_V^{\mathrm{3D}} \sim 2/3$) spanning $0.05$–$20$~pc in the Polaris Flare using PPCOS $^{12}\text{CO}$ data. A transition scale at $\sim 0.5$~pc marks a bifurcation in the structure functions' exponents, below which the degree of intermittency is also saturated. By deriving an analytical mapping relation ($\alpha_V^{\mathrm{3D}}=\alpha_V-\frac{1}{3}\alpha_I$), we obtain the scale-invariant value of $\alpha_V^{\mathrm{3D}}$, proving that the apparent transition stems from geometric projection and a changing density fractal dimension rather than a turbulent mode shift. Kolmogorov turbulence is smoothly inherited from the large-scale cold neutral medium, remaining uninterrupted by compression or gravity below 0.1 pc.
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High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Dark matter energy exchange in stars orbiting supermassive black holes

Stephan A. Meighen-Berger, R. Andrew Gustafson, Nicole F. Bell et al. (+3 more)

Stars on tight orbits around the supermassive black hole at the Galactic Center pass through regions where the dark matter~(DM) density may be strongly enhanced. We compute the orbit-averaged DM-induced energy exchange for S4714 as an example. It is a star on an exceptionally close and relativistic orbit around Sagittarius~A*. For a spiked dark matter profile, the exchange reaches the stellar luminosity at $\sigma_{\chi p} \sim 10^{-36}~\mathrm{cm}^2$ for MeV-GeV masses and $\sigma_{\chi e} \sim 5\times10^{-38}~\mathrm{cm}^2$ for sub-MeV masses, opening a new annihilation-free route toward dark-star phases. These cross sections lie within the range predicted by freeze-in scenarios and are consistent with cosmic-ray–boosted and solar-reflection dark matter constraints.
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All authors Stephan A. Meighen-Berger, R. Andrew Gustafson, Nicole F. Bell, Jayden L. Newstead, Sandra Robles, Ian M. Shoemaker