Current date: 2026-09-23
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Datestamp limit: 2026-09-23 (0 days ago)
Created/updated limit: 2026-09-16 (7 days ago)
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Scoring abstracts
Number of records retrieved: 858
Keyword score statistics
score 9 -- 1 abstracts
score 7 -- 1 abstracts
score 6 -- 4 abstracts
score 5 -- 6 abstracts
score 4 -- 6 abstracts
score 3 -- 9 abstracts
score 2 -- 19 abstracts
in total -- 46 abstracts
Articles that appeared on 2026-09-23
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[abstract 1 / 46] Wow! (score: 9)
- Title: Self-consistent modeling of energy-dependent SYNCHROTRON POLARIZATION in BLAZARs with application to Mrk 421Authors: Frederike Apel, Motseothata Tisang, Victor Barbosa Martins, Xavier Rodrigues, Markus Böttcher, Anna Franckowiak,Comments: Submitted to A&A. Contains 13 pages, 12 figuresSubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Observations of BLACK HOLE JETs closely aligned with our line of sight, known as BLAZARs, have revealed that their X-ray emission can be significantly more polarized than in the optical bands. This chromatic POLARIZATION is often attributed to an energy-stratified JET. In BLAZARs with X-ray emission dominated by electron SYNCHROTRON, the pitch angle between the MAGNETic field lines and electron velocity might also affect the frequency dependence of the POLARIZATION degree, but this effect is generally neglected in state-of-the-art models. In this work, we model the POLARIZATION and spectral energy distribution of BLAZARs, accounting for the system's temporal evolution and pitch-angle-dependent electron SYNCHROTRON cooling. Our analysis investigates the impact of the MAGNETic field structure and electron distribution on POLARIZATION and tests whether this can help explain its observed frequency dependence. By extending the numerical simulation code AM3, we incorporate a self-consistent calculation of electron SYNCHROTRON emission and simulate various MAGNETic-field structures. We apply these models to Mrk 421 and compare them with observations. Finally, we present a time-dependent shock-in-JET model to investigate frequency-dependent POLARIZATION angle swings. Our results show how different MAGNETic-field structures affect energy-dependent POLARIZATION signatures. In the case of Mrk 421, the data can be explained by a helical field in the JET. In the shock-in-JET scenario, the X-ray POLARIZATION angle changes by 70 degrees, while remaining almost constant in the optical/infrared. Our results demonstrate that a self-consistent treatment of the temporal evolution of electrons is essential to model the polarized SYNCHROTRON emission from BLAZARs and can naturally explain chromatic POLARIZATION signatures without requiring an energy-stratified JET.
[abstract 2 / 46] Wow! (score: 7) - Title: The impact of flickering variability and MAGNETisation on the dynamics, stability and morphology of radio-loud AGN JETsAuthors: Emma L. Elley, James H. Matthews, Henry Whitehead, Alex J. Cooper,Comments: AcceptedSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
The physics governing the morphology of radio-loud AGN JETs is not fully understood. We investigate how MAGNETization, flickering JET power and their interplay affects the morphology of RADIO GALAXies. We present a grid of RELATIVISTIC MAGNETohydrodynamic simulations using the PLUTO code covering constant and variable JETs with two levels of MAGNETisation. We find that the constant high MAGNETisation JETs can lead to highly asymmetrical cocoon morphologies, whilst the variable high MAGNETisation JET can exhibit a broken morphology, caused by a discontinuous JET beam. Our work highlights the importance of MAGNETisation and variability on the stability and resulting morphology of radio-loud AGN JETs, suggesting both are significant factors in addition to JET power or environment. Furthermore, we show that the interaction between MAGNETisation and variability can lead to the development of localised kink instabilities along the JET beam. Finally, we discuss the effects of hydrodynamic mixing in low MAGNETisation JETs and the role of viewing angle dependence in comparisons between our simulations and observed sources. To facilitate this comparison we present a library of simulated radio images at different times in the simulations and from various viewing angles, which highlight a diverse set of complex morphologies.
[abstract 3 / 46] Yes (score: 6) - Title: Detection of TeV emission during early afterglow from poorly localized GRBs with ground based IACTsAuthors: S. Macera, B. Banerjee, J. Green, M. Seglar-Arroyo, G. Oganesyan, P. Tiwari, A. Ierardi, M. Branchesi, F. Aharonian, S. Mohnani, D. Miceli, F. Schüssler, A. Berti,Comments: Revised version, submitted to A&ASubjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Gamma-ray bursts (GRBs) are among the most luminous and rapidly evolving transients in the Universe. While space-based instruments have extended GRB observations up to energies of $\sim$100 GeV, the detection of very-high-energy (VHE; $E>100$ GeV) emission from ground-based telescopes, especially during prompt or/and the early afterglow phase, remains challenging. These difficulties arise from the rapid temporal decay of GRB afterglows, strong attenuation by the extragalactic background light (EBL), observational latency, and the typical poor sky localization provided by MeV-detectors such as FERMI/GBM. In this work, we investigate the prospects for detecting TeV ($\sim$100 GeV--1 TeV) emission from poorly localized GRBs by adopting optimized follow-up strategies based on rapid tiling of large localization regions. We simulate a realistic population of GRBs informed by more than fifteen years of FERMI/GBM and SWIFT/XRT detections and recent progresses in the afterglow emission modeling. Using these simulations, we evaluate the detectability of GRB early afterglows by the next-generation Imaging Atmospheric Cherenkov Telescopes, equipped with larger field-of-view (FoV), as a function of latency, exposure time, and observational strategy. Our strategy can significantly enhance the detection rate; for instruments such as ASTRI and LACT, it increases by up to a factor of two compared to strategies limited to well-localized (SWIFT-like) events. For CTAO, our proposed approach provides up to four VHE detections per year.
[abstract 4 / 46] Yes (score: 6) - Title: Thermal and non-thermal emission from supermassive BLACK HOLE circumbinary disks: Disks, Coronae, Streams, and CavitiesAuthors: Chris Nagele, Julian H. Krolik, Brooks E. Kinch, Jeremy D. Schnittman, Scott C. Noble,Comments: Submitted to ApJ Comments welcome!Subjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
The search for electroMAGNETic signals from supermassive BLACK HOLE (SMBH) binary systems is one of the cornerstones of multi-messenger astrophysics, complementing gravitational wave observations of such systems by pulsar timing arrays and LISA. Although extensive simulations have been run to understand the time variability of the bolometric luminosity from accreting binary SMBH systems, comparatively few spectral predictions have been made, and none that go beyond simple emission models. In this paper, we post-process a \texttt{HARM3D} simulation snapshot of a binary at $20 M$ separation accreting at 0.01 Eddington. For BLACK HOLE masses $10^6$, $10^7$, and $10^8\, M_\odot$, we self-consistently solve for the radiated spectrum on the basis of time-steady radiation transfer, thermal balance, and ionization equilibrium, including all relevant RELATIVISTIC effects as well as emission and absorption processes. Although most of the bolometric luminosity is radiated thermally by the disk, the low density regions evacuated by the binary's quadrupole moment produce copious X-rays, with $\sim40\%$ of the observed luminosity in a soft X-ray power law ($Γ= 2.3$). We identify two modes of observed azimuthal variation. The X-ray continuum varies by $\sim10\%$ due to an underlying asymmetry in the gas temperature of spiral shocks in the disk. The Fe~K$α$ equivalent width dips by $\sim25\%$ when the line of sight to the inner disk is partially obscured by the lump. These two effects share the same period and are $\sim π/2$ out of phase; the period is order days to weeks for typical AGN masses and a 20$M$ separation.
[abstract 5 / 46] Yes (score: 6) - Title: A Magnetic Unification of Merging Supermassive Black Hole BinariesAuthors: Mark J. Avara, David O'Neill, Zoltán Haiman,Comments: 34 pages, 19 figuresSubjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
The detection of an electroMAGNETic (EM) transient from a supermassive BLACK HOLE binary (SMBHB) merging within a gaseous environment will constitute a multi-messenger milestone. Numerical simulations of these systems have mostly been performed in 2D with a constant viscosity parameter representing turbulent and MAGNETic stresses. These simulations predict a steep drop in accretion rate and X-ray luminosity at merger, followed by a slow recovery. However, 3D-GRMHD and 3D-MHD simulations have shown only a modest reduction in accretion rate and a fast post-merger recovery. We present a new 2D pseudo-Newtonian framework with physically motivated prescriptions for stochastic viscosity, RELATIVISTIC apsidal precession, and large-scale MAGNETic fields. When suitably calibrated, this 2D framework accurately captures key 3D-GRMHD behavior, demonstrating that it can be used to explore binary accretion without the high computational cost of 3D-GRMHD simulations. We find that the merger signatures are most sensitive to the strength of the MAGNETic field, with a drop in the accretion rate at merger progressively less pronounced for stronger fields. Post-merger evolution is determined by both MAGNETization and RELATIVISTIC precession of orbiting gas, yielding rapid recovery of accretion. For low-MAGNETization disks, recovery is driven by self-intersection shocks, and the dip at merger is followed by a distinct second dimming. Large-scale MAGNETic fields of increasing magnitude lead to MAGNETically arrested disk (MAD) behavior which disturbs the merging system progressively earlier before merger, and longer after. Our results unify the EM signatures of the merger of embedded coplanar SMBHBs, and provide novel observational constraints on their intrinsic MAGNETization.
[abstract 6 / 46] Yes (score: 6) - Title: Current Sheet Fragmentation in the Course of Repeated Eruptive Magnetic Flux EmergenceAuthors: Vaggelis Karantanis, Loukas Vlahos, Heinz Isliker, Angelos Giannis, Vasilis Archontis,Comments: 15 pages, 8 figuresSubjects: astro-ph.SRCreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Magnetic RECONNECTion between emerging MAGNETic flux and the ambient coronal field fundamentally drives solar JETs. We use three-dimensional resistive-MHD simulations of eruptive flux emergence to investigate how the large-scale current sheet formed at the interface fragments during recurrent JET activity. The simulations show that JET formation and current-sheet disruption are coupled elements of a single multiscale process. The current structures developing along open field lines and within the JET are relatively weak, exhibiting a predominantly filamentary morphology. In contrast, the larger structures linked to the closed-field topology are noticeably stronger, and the eruptive development of the emerging flux further increases both their number and strength. The parallel-current distributions within the closed MAGNETic field lines region exhibit Gaussian central cores with pronounced non-Gaussian tails, implying a small subset of strong, intermittent structures. Magnetic spectra follow a power law with a Kolmogorov-like slope in the large-scale range, becoming much steeper in the small-scale range---consistent with RECONNECTion-mediated MAGNETic structuring. Box-counting analysis shows that the strongest current structures have a fractal dimension $D_{\mathrm{f}} \simeq 2$, indicating a fragmented population of sheet-like coherent structures. Cluster analysis further reveals broad, power-law distributions of cluster volumes and their Ohmic dissipation energies, with individual events reaching $\sim 10^{20}$--$10^{25}$ erg over their estimated lifetimes. These results demonstrate that eruptive flux emergence can self-consistently transform a global RECONNECTing current sheet into a localized, intermittent, sheet-dominated dissipative network, providing a natural environment for impulsive coronal heating and motivating future particle-acceleration studies.
[abstract 7 / 46] Yes (score: 5) - Title: Magnetic Eruption and Nucleosynthesis in GRνMHD Simulations of Spinning Neutron Star MergersAuthors: Allen Wen, Jay V. Kalinani, Michail Chabanov, Manuela Campanelli, Riccardo Ciolfi, Yosef Zlochower,Comments: 23 pages, 28 figures, REVTeX 4.2, accepted to PRDSubjects: astro-ph.HE gr-qcCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We present three-dimensional general RELATIVISTIC MAGNETohydrodynamics simulations of equal-mass binary neutron star mergers with varied neutron star spin configurations and second-moment neutrino transport, following the formation and early evolution of long-lived remnants. We compare a fiducial irrotational binary with binaries having spins that are aligned or antialigned with the orbital angular momentum, and examime how spin affects the merger dynamics, MAGNETic field evolution, outflows, and nucleosynthesis. Compared to the fiducial case, the aligned spin configuration releases more cold, neutron-rich tidal ejecta in the equatorial plane, which enables the development of a more tightly collimated polar outflow erupting from the remnant and inner accretion disk. Conversely, the case with spins antialigned with the orbit experiences a more violent collision at merger, disrupting MAGNETic amplification, loading the environment with debris, and impeding the propagation of MAGNETically driven winds. Strong neutrino reprocessing of the polar outflow in the irrotational and aligned spin cases produces $2.4\times 10^{-3}\,M_\odot$ of proton-rich ($Y_e \geq 0.49$) material, resulting in the synthesis of light r-process elements, whose subsequent decay potentially sends a unique electroMAGNETic signal from long-lived remnants. However, the outflows remain too dense and slow to be consistent with typical short GAMMA-RAY BURSTs.
[abstract 8 / 46] Yes (score: 5) - Title: Profile Analysis of the Multiwavelength 2.1-year Oscillations of PG 1553+113Authors: P. Peñil, N. Torres-Albà, A. Rico, L. Marcotulli, A. Domínguez, M. Ajello, S. Buson, S. Adhikari,Comments: 21 pages, 10 figues, 5 tables Published in the Open Journal of AstrophysicsSubjects: astro-ph.GACreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We investigate the morphology of the oscillation profiles of the BLAZAR PG~1553+113 in relation to its well-known $\sim$2.1 yr periodicity. We identify individual cycles in the $γ$-ray, X-ray, UV, and optical light curves and characterize their temporal profiles using analytical models for single- and multi-peaked events. We find that the oscillations are generally described by a broad activity envelope with shorter-timescale substructure, showing that the $\sim$2.1 yr signal is not a strictly sinusoidal or self-similar modulation. The internal morphology varies across cycles and energy bands. This is particularly evident in X-rays, where all analyzed cycles show a strong formal preference for multi-component profiles, unlike the $γ$-ray band, where several cycles admit statistically comparable empirical descriptions. The contemporaneous MWL oscillations show broadly aligned activity episodes, but the timing and relative amplitudes of secondary components are not systematically repeated. This suggests that a common long-term modulation affects the broadband emission, while additional local or energy-dependent processes shape individual cycles. Such a picture is compatible with a geometric, JET-related contribution to the broad recurrent envelope, with intrinsic variability superimposed on it. We also identify new cycles with a dominant peak accompanied by weaker twin-peak-like features, similar to structures previously discussed in a supermassive BLACK HOLE binary scenario for PG~1553+113. Although our results do not provide definitive evidence for this interpretation, the recurrence of comparable morphologies in newly analyzed cycles keeps this scenario viable.
[abstract 9 / 46] Yes (score: 5) - Title: Plasma Heating and Energization in Hot-Onset Flare Precursor EventsAuthors: H. Da, J. F. Drake, M. Swisdak,Comments:Subjects: astro-ph.SRCreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Recent observations of solar flares have revealed a distinct 'hot onset' phase preceding the impulsive phase, characterized by elevated plasma temperature (>10 MK), a steady increase in emission measure, and the absence of detectable nonthermal emission. The standard flare model attributes the formation of hot flare plasma to chromospheric evaporation driven by energy deposition from nonthermal electrons, and therefore does not naturally explain why thermal heating precedes nonthermal emission. Motivated by recent observations of guide-field evolution in two-ribbon flares and by large-scale MHD simulations, we investigate hot-onset energization using simulations of MAGNETic RECONNECTion with the kinetic macroscale model kglobal initialized with a spatially non-uniform guide field. Because the efficiency of electron non-thermal energy production from FERMI acceleration decreases with guide-field strength, the evolving guide field produces two distinct energization regimes. During the initial high-guide-field phase, the bulk electron temperature rises to approximately twice its initial value, while non-thermal particle production remains weak. Upon entering the low-guide-field regime, energetic particle production is significantly enhanced, with the population of high-energy electrons growing rapidly. These findings provide a self-consistent physical explanation for the hot onset, demonstrating that the macroscopic evolution of the guide field naturally bridges the hot-onset and impulsive phases of solar flares without requiring a separate trigger mechanism.
[abstract 10 / 46] Yes (score: 5) - Title: Multi-scale variability in the optical afterglow of GRB 251013C from high-cadence LAST observationsAuthors: R. Konno, E. O. Ofek, S. Garrappa, O. Teboul, E. Waxman, S. Ben-Ami, D. Kovaleva, A. Krassilchtchikov, D. Polishook, E. Segre, E. A. Zimmerman,Comments: submitted to A&ASubjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Context. Optical afterglows of GAMMA-RAY BURSTs (GRBs) are often described by smooth power-law decays, but deviations such as flares and rebrightenings provide important constraints on the underlying emission processes. Aims. We investigate the temporal variability of the optical afterglow of GRB 251013C using high-cadence observations, and assess the origin of the observed variability. Methods. We analyze continuous optical observations obtained with the Large Array Survey Telescope (LAST), complemented by publicly available X-ray data from SWIFT-XRT. The optical light curve is modeled using a power-law decay with superposed variability components, and contemporaneous optical and X-ray measurements are used to constrain the broadband spectrum. Results. The optical light curve shows pronounced variability on multiple timescales, including broad rebrightening episodes with $Δt \sim t$ and superposed faster fluctuations with $Δt/t < 1$. The main rebrightening exhibits a structured rise with a clear steepening prior to the peak. The fast variability comprises asymmetric fast-rise, slow-decay features whose durations increase with peak time. The optical flux lies on the extrapolation of the X-ray spectrum, and the spectrum hardens by the same amount whether measured within the X-ray band or from optical to X-ray. Conclusions. We favor a refreshed external-shock interpretation for the main rebrightening. The broadband spectrum and post-peak decay are consistent with slow-cooling SYNCHROTRON emission in a wind-like medium. The spectral hardening requires a newly dominant, harder electron population, while the faster optical variability indicates structure within the refreshed ejecta or shocked region.
[abstract 11 / 46] Yes (score: 5) - Title: Convolutional Neural Network for Extraction of $n = 1$ Photon Ring of Black HolesAuthors: Courtney Duong, Frank Myhre, Joseph R. Farah,Comments: 12 pages, 10 figures, accepted in ApJSubjects: astro-ph.IM astro-ph.HECreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Very-long-baseline interferometry (VLBI) may enable direct imaging of fine, event-horizon scale BLACK HOLE structures such as the photon ring. In particular, the $n=1$ photon subring encodes information about BLACK HOLE spin in its radial profile and azimuthal brightness modulation, making it a key proxy for spacetime properties. However, the $n=1$ subring overlaps with emission from the $n=0$ subring in observations, requiring isolation of the $n=1$ subring for measurements. We present a convolutional neural network (CNN) capable of extracting the $n=1$ subring from composite images containing $n=0$ and $n=1$ subrings. We simulate $111,000$ $m$-ring images with \texttt{eht-imaging} to train and validate the CNN. The CNN accurately recovers the radial and angular brightness profiles of the $n=1$ subring with a mean normalized cross correlation (NXcorr) of $\sim0.99$. The CNN provides a detection capability by predicting no false positives when input images lack a $n=1$ subring. We perform feature extraction with \texttt{ringfit} to show that the CNN-predicted $n=1$ subring accurately recovers the ground truth radial profiles and azimuthal brightness modulation, demonstrating the CNN's capability to extract spin-sensitive features. We further test the CNN on BLACK HOLE images generated by \texttt{KerrBAM} and general RELATIVISTIC MAGNETohydrodynamic (GRMHD) simulations, finding that it recovers the overall $n=1$ subring radial profiles while exhibiting discrepancies in the recovered intensity profiles. These results demonstrate the potential of deep learning methods to isolate the $n=1$ subring from overlapping emission, providing a framework for analyzing future high resolution BLACK HOLE images from proposed VLBI missions such as the Black Hole Explorer (BHEX).
[abstract 12 / 46] Yes (score: 5) - Title: Einstein Probe discovery of the MAGNETar EP J223759.5+531421Authors: N. Rea, F. Coti Zelati, A. Borghese, Y. L. Wang, H. Yang, X. Mao, C. -Y. Dai, E. Arrigoni, J. Bai, G. Bernardi, M. Burgay, S. Cao, A. Coleiro, D. De Grandis, P. Esposito, H. Feng, Y. -C. Fu, A. Geminardi, D. Götz, S. Guillot, Y. Huang, M. Imbrogno, G. L. Israel, C. Jin, A. Kong, Y. Li, L. Lin, C. -S. Liu, C. Maitra, A. Marino, S. Mereghetti, J. -U. Ness, S. Ng, M. Pilia, A. Possenti, H. Sun, L. Tao, R. Taverna, A. Tiengo, R. Turolla, W. Yuan, S. Zane, B. Zhang, L. -X. Zhang, Z. Zhang, W. -W. Zhu, Y. -C. Zou,Comments: 15 pages, 10 figures, 6 tables, submitted to A&ASubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We report the discovery and early outburst evolution of the new Galactic MAGNETar EP J223759.5+531421, detected by the Einstein Probe Wide-field X-ray Telescope on 2026 June 28. Follow-up observations with Einstein Probe, XMM--Newton, NUSTAR, SVOM, and IXPE revealed coherent X-ray pulsations at P ~ 6s and an average period derivative of Pdot ~ 2.8x10^{-12} s/s. These values imply a nominal polar dipolar MAGNETic field of B_dip ~ 2.6x10^{14} Gauss and a characteristic age of tau_c ~ 34 kyr, although the structured timing residuals suggest possible torque variability. The rms pulsed fraction is approximately 20-25% below ~7 keV and decreases at higher energies. The broadband spectra require multiple thermal components and a hard power-law tail. Adopting a distance of 3.3 kpc, the 0.5-30 keV luminosity declined from 1.2x10^{35} to 5.7x10^{34} erg/s during the first month, accompanied by a decrease in the inferred thermal-emitting areas. At this distance, the Galactic latitude b=-4.56 deg corresponds to a height of approximately 0.26 kpc below the Galactic plane, which is difficult to reconcile with the nominal characteristic age under a simple midplane-birth scenario even for an extreme proper motion velocity. Short X-ray bursts independently confirm the MAGNETar nature of the source. No near-infrared or radio counterpart were detected by GTC, Medicina or FAST, respectively, down to K_s>21 mag and S_{1.25 GHz} <2.3 microJy. These observations demonstrate the potential of the Einstein Probe WXT monitoring to uncover previously quiescent Galactic MAGNETars and follow their outbursts from their earliest observed stages.
[abstract 13 / 46] Yes (score: 4) - Title: Deciphering the Physical Origin of GRB 240825A: A Long GRB Lacking a Bright SupernovaAuthors: Rahul Gupta, Judith L. Racusin, R. Sanchez-Ramirez, Y. Hu, Andrea Rossi, Maria Dolores Caballero Garcia, Pi Nuessle, Alberto J. Castro-Tirado, Samantha Oates, Pragyan P. Bordoloi, Amar Aryan, Simone Dichiara, Peter Veres, Noel Klingler, Nicola Omodei, Elisabetta Maiorano, Donggeun Tak, S. Shilling, Jose E. Adsuara, P. H. Connell, E. Fernandez Garcia, Guillermo Garcia-Segura, Ankur Ghosh, Ersin Göğüs, Francisco J. Gordillo-Vazquez, Maria Gritsevich, Ana M. Nicuesa Guelbenzu, S. Guziy, Lorraine Hanlon, Hendrik van Heerden, Shabnam Iyyani, Antonio Martin-Carrillo, Petrus J. Meintjes, J. Navarro-Gonzalez, T. Neubert, Nikolai Ostgaard, S. B. Pandey, Ignacio Pérez-García, Soebur Razzaque, Eda Sonbas, Si-Yu Wu, Alexei Pozanenko, Alina Volnova, Alexander Moskvitin, Sergey Belkin, O. I. Spiridonova, Otabek A. Burkhonov, Shuhrat A. Ehgamberdiev, E. Klunko, V. Rumyantsev, I. Sokolov, A. Novichonok, Inna Reva, A. Volvach, L. Volvach, Jan Snigula, Chiara Ventura,Comments: 30 pages, 21 figures, 6 tables, accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We present a comprehensive multiwavelength analysis of GRB 240825A, a bright GAMMA-RAY BURST (GRB) detected by FERMI and SWIFT, with a prompt duration ($T_{\rm 90}$ $\sim$ 4 sec in 50-300 keV in GBM) near the boundary separating short and long GRBs, prompting a detailed investigation into its classification and progenitor. We use classical prompt metrics (duration, minimum variability timescale (MVT), lag, and spectral hardness) and modern classification techniques (machine-learning (ML) based t-SNE, support vector machine, energy-hardness-duration, and $\varepsilon \equiv E_{γ,\mathrm{iso},52} / E_{p,z,2}^{5/3}$) and find most properties (prompt energetics, placement on the Amati relation, and spectral lag) of GRB 240825A consistent with a collapsar origin. However, extensive late-time optical and NIR follow-up with the 10.4m GTC and 8.4m binocular LBT telescopes reveals no bright SUPERNOVA (like SN 1998bw) is detected down to stringent limits (e.g., $m_r > 25.0$ mag at 17.59 days), despite a redshift of $z = 0.659$ measured from GTC spectroscopy. Host galaxy SED modeling with Prospector indicates a massive, and star-forming galaxy-typical of collapsar GRB hosts, though with a large offset. We compare these findings with hybrid events like GRB 211211A, GRB 230307A, GRB 200826A, including SNe-GRBs, and conclude that GRB 240825A most likely originated from a massive star collapse, possibly with the associated SN heavily obscured or intrinsically faint. This study emphasizes the need for multiwavelength follow-up and a multi-layered classification to determine GRB progenitors.
[abstract 14 / 46] Yes (score: 4) - Title: Diffuse gamma-ray emission in the vicinity of open cluster Berkeley 87Authors: Ziwei Ou, Xiaolong Yang,Comments:Subjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Young massive stellar clusters have been recognized as a significant population of COSMIC RAY accelerators and gamma-ray sources. We report the detection of extended gamma-ray emission toward the young massive star cluster Berkeley 87 using 18 years of FERMI-LAT data. The hadronic scenario is favored given the dense gas and the cluster's strong stellar winds. The cluster can supply sufficient energy to power the observed gamma-ray emission. A nearby pulsar, PSR J2021+3651, associated with the Dragonfly pulsar wind nebula and the 4HWC source 4HWC J2021+3650, lies in the same field of view. We also discuss the maximum accelerated proton energy and electron energy density of this pulsar.
[abstract 15 / 46] Yes (score: 4) - Title: A Multi-Mission Detection Framework for High-Energy Transients: Application to a 13-year FERMI/GBM and SWIFT/BAT SampleAuthors: Ariel Perera, Barak Zackay, Tejaswi Venumadhav,Comments:Subjects: astro-ph.HE astro-ph.IMCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
The detection of faint high-energy transients is becoming increasingly important in time-domain and multi-messenger astronomy, particularly for identifying electroMAGNETic counterparts to binary neutron star mergers, high-energy neutrino events, and other weak transient phenomena. At present, the sensitivity of gamma-ray and hard X-ray searches is often limited by the detection threshold of individual instruments, leaving a population of faint transients inaccessible to single-mission analyses. To address this limitation, we develop a joint detection framework that combines trigger information from multiple detectors and assigns each candidate a joint association probability, $p_{\text{joint}}$, as a function of the individual detector signal-to-noise ratios. We apply this framework to archival FERMI/GBM and SWIFT/BAT rates data from 2013-2025. The method effectively separates coincident signals from accidental background associations, suppressing inconsistent coincidences while enhancing the significance of faint events observed by both instruments. We find that, under optimal conditions, a two-mission search can increase the accessible volume for short GAMMA-RAY BURSTs by up to $60\%$. This framework provides a practical foundation for generalized multi-mission searches, enabling more sensitive exploration of the faint high-energy transient sky and improving the prospects for future multi-messenger discoveries.
[abstract 16 / 46] Yes (score: 4) - Title: A Brief Review on the Statistical Properties of Fast Radio BurstsAuthors: Yu Sang, Hai-Nan Lin,Comments: 39 pages, 4 figuresSubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Fast radio bursts (FRBs) are millisecond-duration radio transients of extragalactic origin, whose emission mechanisms and progenitors remain unresolved. Statistical analyses of the rapidly growing samples provide a promising means to constrain the underlying physics. In this review, we synthesize the statistical properties derived from current FRB catalogs, encompassing constraints on dispersion measure, redshift, energy/luminosity functions, repetition rate, and host-galaxy demographics. For repeating FRBs, we examine the statistics of energy, fluence/flux, waiting time, and discuss time-series analyses that reveal memory effects and chaotic dynamics. We further discuss the observational discovery and theoretical interpretation of periodic activity, and survey POLARIZATION properties that probe the MAGNETo-ionic environments of FRB sources. Throughout, we emphasize robust empirical trends, account for observational biases and selection effects, and outline outstanding open questions regarding the physical origin of these enigmatic bursts.
[abstract 17 / 46] Yes (score: 4) - Title: Kink instability as a particle acceleration mechanism in X-ray binaries and the connection to the outburst cycleAuthors: Emma L. Elley, James H. Matthews, Alex J. Cooper, Fraser J. Cowie, Rob Fender,Comments:Subjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We consider whether the kink instability can explain particle acceleration in hard state 'compact' X-ray binary JETs. We apply a 1D model to assess the expected growth rate of the instability for a variety of JET models, then scale results from simulations to estimate a dissipation rate for the MAGNETic energy in the JET. We then consider the effects of radiative cooling on the system. We find that hard state 'compact' X-ray binary JETs are likely to be unstable to the kink instability within their acceleration zones across a plausible parameter space. We further find that depending on the parameters of the model, the JETs may radiate over a variety of length scales ranging from length scales attributable to a 'failed' JET scenario, to those in keeping with resolved radio observations of 'compact' JETs. We discuss the expected evolution of this model through the outburst cycle.
[abstract 18 / 46] Yes (score: 4) - Title: KPolaris: GPU-accelerated Polarized Radiative Transfer in General RelativityAuthors: Zelin Zhang, Bin Chen,Comments: 15 pages, 4 figures, 8 tablesSubjects: astro-ph.HE gr-qcCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Polarized black-hole images carry information about both the MAGNETized plasma and the curved spacetime through which the radiation propagates. We present KPolaris, an open-source GPU-accelerated general-RELATIVISTIC polarized radiative-transfer code built on the Kokkos framework. It supports analytic plasma models and GRMHD simulation data, with both fast-light and slow-light radiative transfer. The code also provides diagnostics that connect image structure to the emitting plasma and to propagation effects along the rays. These include emissivity-weighted plasma maps, emission contributions from selected regions, selected-ray histories, and sensitivities of the Stokes parameters to plasma parameters. Numerical convergence tests and comparisons with an independent radiative-transfer code assess the accuracy of the calculations. GPU acceleration reduces the computational cost of image generation, facilitating multi-frequency and time-dependent studies of polarized black-hole images.
[abstract 19 / 46] (score: 3) - Title: Bridging the gap between SLSNe and SE-SNe. Multi-wavelength analysis of the SLSN-Ib SN 2024jlcAuthors: 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,Comments: Published on A&ASubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
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 $γ$-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 \textit{FERMI}-LAT data, from which we report an intriguing hint of a $γ$-ray signal at the $\sim 3.6 σ$ level, although no firm detection can be claimed. The gamma to optical efficiency ratio, $η= 0.38$, 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.
[abstract 20 / 46] (score: 3) - Title: Searching for optical pulsations from spider millisecond pulsars with the fast photometer SiFAP2Authors: Christian Malacaria, Alessandro Papitto, Filippo Ambrosino, Caterina Ballocco, Riccardo La Placa, Giulia Illiano, Arianna Miraval Zanon, Luigi Stella, Marco Turchetta, James D. Turner, Clara Blanchard, Ignacio Cognard, Lucas Guillemot, Marta Burgay, Aleksandr Burtovoi, Andrea Sanna, Sergio Campana, Massimo Cecconi, Adriano Ghedina, Andrea Possenti, Diego Torres,Comments: 10 pages, accepted on A&A, language editedSubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Optical pulsations from millisecond pulsars (MSPs) have recently been detected in a transitional MSP and an accreting MSP. Evidence for optical pulsations has also been found for a rotation-powered redback MSP. Observations suggest that optical pulsed emission is produced by different mechanisms depending on whether an accretion disk is present in the system. We explored a sample of rotation-powered MSPs in close binaries (P$_{orb}<1\,$day; redbacks and black widows), searching for optical periodic signals with the $SiFAP2$ photometer mounted on the $Telescopio\,Nazionale\, Galileo$ (TNG). We performed pulsation searches using the epoch-folding method with the most up-to-date (radio or gamma-ray) orbital solution for each system. These solutions were based either on previously published works or recent observations from Nançay, the Giant Metrewave Radio Telescope, the Parkes Observatory, and $FERMI$-LAT. We update or confirm radio and gamma-ray ephemerides for five of the presented systems. No optical pulsations were detected with a significance exceeding a $3σ$ confidence level in any of our searches, despite achieving sensitivities close to the instrument's limit. This places correspondingly stringent upper limits on the systems' optical pulsed magnitude and conversion efficiency. Our upper limits are consistent with the pulsed optical luminosity of optical pulsations from the redback PSR J2339-0533. Compared to accreting and transitional MSPs, redback and black widow systems show much lower efficiency in converting their spin-down power into pulsed optical emission. This supports the recent suggestion that the accretion disk around the neutron star plays a role in accelerating the particles responsible for producing bright optical pulsed emission.
[abstract 21 / 46] (score: 3) - Title: Why MHD turbulence forms sheets: energy conversion and cascade geometryAuthors: Damiano Capocci, Moritz Linkmann,Comments:Subjects: physics.plasm-ph physics.flu-dynCreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Sheet-like structures are ubiquitous in MAGNETohydrodynamic systems and are known to play a crucial role in astrophysical plasma transport. Here, by applying a theoretical framework to data from numerical simulations, we demonstrate that current-sheet formation is a direct consequence of energy conversion between kinetic and MAGNETic fields. The strain-MAGNETic field organisation associated with this conversion favours the emergence of sheet-like structures, and analytical calculations show that sheet-like geometry constitutes the dominant flow configuration. We further show that the same conversion-driven reorganisation of the strain motion is responsible for the depletion of the mean Inertial energy transfer, a previously observed phenomenon whose physical origin has remained unclear. Finally, we identify experimentally accessible diagnostics through which these predictions can be tested in multi-spacecraft observations of turbulent plasmas.
[abstract 22 / 46] (score: 3) - Title: Axial Perturbations of Charged Kiselev Black Holes in Rastall Gravity: Matter Response and Quasinormal ModesAuthors: Yan Wang, Yun-tao Gu, Wen-Di Guo,Comments: 42 pages,6 figures,4 tablesSubjects: gr-qcCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We investigate axial gravitoelectroMAGNETic quasinormal modes of a charged BLACK HOLE surrounded by dust-like Kiselev-type anisotropic matter in Rastall gravity. Under a closure prescription that neglects perturbations of the anisotropy direction, the system reduces to two coupled Schrödinger-type equations. These equations admit an $r$-independent algebraic decoupling in the Reissner--Nordström and general-RELATIVISTIC dust-like limits, but such a decoupling is generically obstructed when both the Rastall modification and the surrounding-matter contribution are present. For comparison, we introduce an auxiliary frozen-source truncation, whose potential matrix differs from the matter-response matrix in only two entries. For the axial dipole, the matter-response system has one-way coupling, whereas the truncated reference system has two-way coupling. Nevertheless, representative fundamental frequencies of the matter-response system and the reference system differ only at the sub-percent level. A Chebyshev pseudospectral calculation, validated through the Reissner--Nordström limit and spectral-convergence tests, shows that increasing the dimensionless Rastall coupling $γ$ lowers both the oscillation frequency and the damping rate in the small-$γ$ region. In the large-$γ$ region, the oscillation frequency rises, whereas the damping rate varies nonmonotonically. A larger black-hole charge generally raises the oscillation frequency, whereas stronger surrounding-matter contributions tend to produce longer-lived modes. All surveyed fundamental axial modes satisfy $\operatorname{Im}ω<0$.
[abstract 23 / 46] (score: 3) - Title: IXPE observation of the new MAGNETar source EP J223759.5+531421Authors: Roberto Taverna, Lorenzo Marra, Roberto Turolla, Ruth M. E. Kelly, Silvia Zane, Alice Borghese, Francesco Coti Zelati, Paolo Esposito, Gian Luca Israel, Nanda Rea, Haonan Yang, Yilong Wang,Comments: 14 pages, 9 figures, submitted to ApJLSubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We report on the detection of polarized X-ray emission from the new Galactic MAGNETar EP J223759.5+531421, discovered by the Einstein Probe Wide-field X-ray Telescope on 2026 June 28. The Imaging X-ray Polarimetry Explorer (IXPE) follow-up observation started on 2026 July 6 and detected the source at a (absorbed) flux of $\approx 4.5\times 10^{-11} \, \mathrm{ erg\,cm^2\,s}^{-1}$ ($2$--$7.5\, \mathrm{keV}$ range), confirming the presence of two thermally emitting regions on the star surface, with temperatures $\approx 0.5$ and $\approx 1\, \mathrm{keV}$. A significant (at $> 4σ$ confidence level) phase- and energy-integrated POLARIZATION degree of $\approx 7\%$ was detected with the POLARIZATION angle $\approx -2^\circ$ East of the celestial North. The two thermal components exhibit quite different POLARIZATION properties, with the hotter one being more polarized. The difference is larger in the phase-folded data, with the POLARIZATION degree reaching $\sim 63\%$ in the range $4$--$7.5\,\mathrm{keV}$, in correspondence with the secondary peak of the pulse profile, and never exceeding $\sim 30\%$ at lower energies. The POLARIZATION angle continuously oscillates from $-90^\circ$ to $+90^\circ$ over one rotational cycle and is well fit by the rotating vector model, with an inclination of the line of sight and of the MAGNETic dipole axis relative to the star spin axis of $\approx 28^\circ$ and $\approx 109^\circ$, respectively. The data point to an emission geometry in which the cold thermal component likely originates from two antipodal caps, possibly in a MAGNETically condensed state, while the hotter one comes from a smaller region covered by an atmosphere.
[abstract 24 / 46] (score: 3) - Title: Inelastic scattering effects on POLARIZATION predictions for cold and warm atmospheres in the X-raysAuthors: J. Podgorný, L. Marra, M. Dovčiak, R. Taverna, R. W. Goosmann, M. Gupta, F. Marin, G. Matt, J. Poutanen, A. Różańska, A. Veledina,Comments: 9 pages, 3 figures, submitted to ApJLSubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
X-ray POLARIZATION models of accreting compact objects often assume the so-called Chandrasekhar-Sobolev POLARIZATION prescription for elastic Thomson scattering in electron-scattering semi-infinite atmospheres. In this letter, we examine the effects of inelastic Compton scattering. We assume homogeneous slabs of cold and warm (up to 1 keV) electrons. We use a Monte Carlo approach. We discuss the POLARIZATION difference arising in the X-rays between the elastic and inelastic scattering assumptions for plane-parallel transmission and reflection, and the role it can play in the interpretation of X-ray polarimetric observations of accreting compact objects.
[abstract 25 / 46] (score: 3) - Title: Dark-matter relay for ultra-high-energy COSMIC RAYsAuthors: Mikhail Sekretov,Comments: 6 pages, 2 figuresSubjects: astro-ph.HE hep-phCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Astrophysical sources of ultra-high-energy COSMIC RAYs (UHECRs) remain unidentified, and no nearby cosmic accelerators are established even for the highest-energy events. In addition, puzzling correlations of a fraction of UHECR flux with distant BLAZARs were found by HiRes and, recently, Telescope Array experiments. Here we propose that DARK MATTER can provide a mechanism to effectively transfer UHECRs from distant sources: dark-matter particles are boosted by UHECRs near the source and pass their momentum to baryons close to the observer. The probability of this relay is not negligible because of the growth of dark-matter-baryon cross section with energy. We demonstrate that the effect is observable for fermionic DARK MATTER of mass $m_{\mathrm{DM}} \sim 25$ MeV and discuss possible observational signatures of this mechanism.
[abstract 26 / 46] (score: 3) - Title: Analytic toroidal 3D MHD equilibria and steady Euler flows with invariant surfacesAuthors: Matt Landreman,Comments:Subjects: physics.plasm-ph math.AP physics.flu-dynCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Families of explicit analytic solutions of the MAGNETohydrodynamic equilibrium equations are presented, equivalent to steady incompressible Euler flow. The solutions are non-axisymmetric and possess exact nested toroidal flux surfaces. No expansion is made in inverse aspect ratio or in the deviation from axisymmetry. The MAGNETic field and flux surfaces are given explicitly in Cartesian coordinates using elementary functions. The field, current density, and scalar pressure are smooth over the toroidal domain. The pressure gradient vanishes only on the MAGNETic axis. One family of solutions has uniform rotational transform $ι=2$, while another family has a sheared $ι$ profile. These counterexamples to Grad's conjecture are valuable for understanding the existence and regularity of 3D equilibria and for testing numerical codes.
[abstract 27 / 46] (score: 3) - Title: Resonant neutrino flavor conversion within DARK MATTER spikesAuthors: P. S. Bhupal Dev, Elisa Gaido, Alejandro Ibarra, Yago Porto,Comments: 11 pages, 8 figuresSubjects: hep-ph astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We investigate how neutrino--DARK MATTER (DM) interactions modify the flavor composition of high-energy neutrinos from ACTIVE GALACTIC NUCLEi (AGNs). Coherent forward scattering in a DM spike around the central supermassive BLACK HOLE can generate a flavor-dependent potential, inducing flavor conversion as the neutrinos escape. We calculate the flavor composition at Earth for pion-decay and muon-damped sources and find substantial departures from vacuum-oscillation expectations. At neutrino energies around $100\,\mathrm{TeV}$, the matter potential begins to compete with vacuum oscillations when the coupling-weighted net DM number density reaches $|ε_α(n_χ-n_{\barχ})|\sim10^{18}\,\mathrm{cm}^{-3}$. We compare our predictions with IceCube flavor triangle measurements under the illustrative assumption that the diffuse flux originates from AGNs with common neutrino-production and DM-spike properties. Under this assumption, when the DM-induced potential acts on the muon flavor and dominates the vacuum terms at production, the $pγ$ muon-damped predictions lie outside the 95\% MESE contour. High-energy neutrino flavor measurements can therefore provide a novel probe of neutrino-DM interactions in astrophysical environments.
[abstract 28 / 46] (score: 2) - Title: Cross-helicity and chaotic dynamics of full-disc solar MAGNETic fieldAuthors: A. Bershadskii,Comments: Extended (new data have been added)Subjects: physics.flu-dynCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Using the results of laboratory experiments and direct numerical simulations, as well as observations of the full-disc solar MAGNETic field and sunspot number dynamics, it is demonstrated that cross-helicity can dominate the decaying part of the frequency power spectra of the MAGNETic field generated by a MAGNETohydrodynamic (MHD) dynamo in chaotic/turbulent swirling flows for sufficiently strong MHD turbulence (including the solar dynamo). The theoretical consideration is based on a Kolmogorov-like phenomenology within the framework of the distributed chaos concept. It is also shown that the solar full-disc MAGNETic field for the last two solar cycles with weak MAGNETic activity exhibits deterministic chaotic behavior concentrated around the equator.
[abstract 29 / 46] (score: 2) - Title: Self-lensing binaries in globular clusters -- predictions for ELTAuthors: Grzegorz Wiktorowicz, Matthew Middleton, Mirek Giersz, Adam Ingram, Adam McMaster, Abbas Askar, Lucas Hellström,Comments: 26 pages, 9 figures, submitted to AcASubjects: astro-ph.GA astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Self-lensing (SL) represents a powerful technique for detecting compact objects in binary systems through gravitational microlensing effects, when a compact companion transits in front of its luminous partner. We present the first comprehensive study of SL probability within globular cluster (GC) environments, utilizing synthetic stellar populations from MOCCA simulations to predict detection rates for the Extremely Large Telescope (ELT). Our analysis incorporates finite-size lens effects for white dwarf (WD) lenses and the specific observational characteristics of the ELT/MICADO instrument. We find that present-day GCs contain 1-50 SL sources with magnifications $μ_\mathrm{sl} > 1+10^{-8}$, strongly dependent on initial binary fraction, with systems dominated by WD lenses paired with low-mass main-sequence companions. The predicted populations exhibit characteristic bimodal magnitude distributions with peaks at $m \approx 24$ and 32 mag at 10 kpc distance, and typical Einstein ring crossing times of $τ_\mathrm{eff} \sim 2$ hours. ELT observations should achieve detection efficiency of 0.015-10 sources in $\sim150$ nearby GC after a year of observations depending on distance and survey strategy, with nearby clusters ($D \lesssim 10$ kpc) offering the highest yields. Multi-year monitoring campaigns with daily cadence provide order-of-magnitude improvements over single observations through enhanced photometric precision and increased detection probability. Our results demonstrate that coordinated ELT surveys of Galactic GCs represent a viable approach for probing hidden binary populations and compact object demographics in dense stellar environments, with comprehensive programs potentially yielding up to 10-100 well-characterized SL sources after first 5 years of observations suitable for statistical studies of binary evolution in extreme environments.
[abstract 30 / 46] (score: 2) - Title: Foiling Black Hole Foils: Revealing Horizon Alternatives with Baryonic AtmospheresAuthors: Shokoufe Faraji, Avery E. Broderick,Comments: 27 pages, 2 figuresSubjects: astro-ph.HE gr-qcCreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Event horizons are a defining feature of BLACK HOLEs. Consequently, there have been many efforts to probe their existence in astrophysical BLACK HOLE candidates, spanning ten orders of magnitude in mass. Nevertheless, horizons remain an obstacle to unifying general relativity and quantum mechanics, most sharply presented by the information paradox. This has motivated a proliferation of horizonless alternatives (BLACK HOLE foils) that avoid event horizons and are therefore presumably benign. We explore the fate of accreting material in the context of spherically symmetric horizonless compact objects in the steady state regime. We find that for typical accreting astronomical targets, foils can develop an optically thick, convectively stable baryonic atmosphere, immediately implying the creation of an emitting photosphere at modest redshift even when the surface redshift is extreme. The emergent photosphere luminosity is driven toward the accretion powered equilibrium value and is only weakly sensitive to the foil redshift. Moreover, local gas-surface interaction provides a microphysical lower bound on the effective base temperature, insulating the atmosphere from arbitrarily cold foils. The unknown properties of the foil enter only through local boundary conditions controlling baryon processing and thermal coupling at the surface, making the solutions broadly applicable to horizonless alternatives that do not invoke significant additional nonlocal interactions. Thus, under minimal assumptions (GR exterior and local surface interactions), spherically symmetric horizonless foils in accreting systems are generically observationally exposed: the absence of a thermal photosphere directly constrains or rules out broad classes of such models.
[abstract 31 / 46] (score: 2) - Title: Galaxy morphology dependent (BLACK HOLE mass)-(velocity dispersion) relations: implications for gravitational wave forecasts and cosmological simulationsAuthors: Alister W. Graham,Comments: 27 pages (including 10 figures and an Appendix for SCOPE: see https://github.com/A-Graham/SCOPE ). To appear in MNRASSubjects: astro-ph.GACreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
The correlation between BLACK HOLE mass, $M_{\rm bh}$, and stellar velocity dispersion, $σ_0$, is revisited using 137 galaxies with quantitative bar strengths and enhanced morphological awareness. Interpreted within the `Triangal' evolutionary framework, gas-rich and gas-poor assembly pathways emerge in the $M_{\rm bh}$-$σ_0$ diagram. To quantify these scaling relations, a symmetric Bayesian hierarchical regression code, dubbed the Symmetric COvariance Population Estimator (SCOPE), is introduced. Unlike conditional estimators (e.g., LINMIX), SCOPE derives the intrinsic population covariance, natively accommodating asymmetric measurement errors while guaranteeing directional invariance between axes. Primeval, dust-poor S0 galaxies (including dwarf early-type galaxies with $R_{\rm e,gal}$ ~ 1 kpc) follow a shallow relation ($M_{\rm bh}\proptoσ_0^{2.5\text{--}3.1}$). Explained via the virial theorem, this flattening reframes expectations for intermediate-mass BLACK HOLEs. In contrast, tracing the `Disc Down-sizing' sequence - where dry mergers erase discs - yields a steep relation for massive elliptical and ellicular galaxies ($M_{\rm bh}\proptoσ_0^{7.8\pm1.4}$). Applying a single, monolithic scaling relation across all morphologies inadvertently averages over different formation histories, potentially skewing AGN virial $f$-factor calibrations and systematically under-predicting the ultra-massive BLACK HOLEs needed to generate the nanohertz gravitational wave background. Furthermore, strongly barred, dust-poor S0 galaxies appear offset to higher $σ_0$, while this dynamical signature is lost in the complexities of spiral galaxies. Ultimately, these morphology-dependent relations provide physically-motivated benchmarks for cosmological simulations and a framework for disentangling regimes driven by AGN feedback from those driven by mergers.
[abstract 32 / 46] (score: 2) - Title: Charge-dependent atmospheric muon flux at 17 GV geoMAGNETic cutoff with the mini-ICAL detectorAuthors: S. Pethuraj, Raj Shah, G. Majumder, J. M. John,Comments: Updated version 26 pages, 18 figures, 2 tablesSubjects: hep-exCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
The Iron CALorimeter (ICAL) detector at the India-Based Neutrino Observatory (INO) was conceived as an underground experiment designed to measure atmospheric neutrino oscillation parameters. As part of the R\&D programme, a scaled prototype (mini-ICAL), 85\,ton, approximately 1/600$^{\mathrm{th}}$ the mass of the full detector, was constructed at the IICHEP Transit Campus, Madurai (altitude 150\,m; latitude 9.9372$^\circ$\,N; longitude 78.013$^\circ$\,E; geoMAGNETic latitude 1.44$^\circ$\,N; vertical cutoff rigidity 17\,GV) and operated between 2018 and 2022. The prototype enabled measurements of charge-dependent cosmic muon spectra in the vicinity of the geoMAGNETic equator and provided an important validation of detector performance, reconstruction algorithms, and simulation frameworks for the ICAL experiment. Differential fluxes of $μ^{-}$ and $μ^{+}$ were measured over the momentum range $\sim$\,1--5\,GeV/c. The obtained momentum spectra are systematically lower than those reported at sites with smaller geoMAGNETic cutoff rigidities, consistent with the suppression of low- and intermediate-rigidity primary COSMIC RAYs at the 17\,GV cutoff. The measurements are compared with predictions from different hadronic interaction models available in CORSIKA simulations.
[abstract 33 / 46] (score: 2) - Title: When the stars don't align: Investigating inconsistencies in binary BLACK HOLE formation across population synthesis codesAuthors: Alexandra G. Guerrero, Michael Zevin, Duncan B. Maclean, Katelyn Breivik, Carl L. Rodriguez, Max M. Briel, Daniel E. Holz,Comments: 40 pages, 22 figures, 1 table. Submitted to ApJSubjects: astro-ph.HE astro-ph.GA astro-ph.SRCreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
Binary population synthesis (BPS) codes are valuable tools for investigating the end-to-end lives of binary stars as well as a myriad of observed astrophysical phenomena. Many ``rapid" BPS codes rely on semi-analytical single-star evolutionary tracks and disjointed prescriptions for binary physics. Updated ``hybrid" or ``detailed" BPS codes incorporate improved methodologies, but at a steeper computational cost that may limit broad exploration of physical uncertainties. Given the widespread use of BPS in modern astrophysical research, it is imperative to systematically compare BPS codes across the spectrum of computational efficiency, flexibility, and physical realism to gauge their consistency and robustness. In this work, we perform BPS on three single-metallicity populations of identical initial binaries using three modern codes --- the rapid code $\texttt{COSMIC}$, the hybrid code $\texttt{METISSE}$ integrated into $\texttt{COSMIC}$, and the detailed code $\texttt{POSYDON}$ --- ensuring consistent physical parameterizations where possible. We find stark differences in the properties, formation pathways, and progenitors of binary BLACK HOLE (BBH) merger populations across the three codes. In a population of one million binaries at $0.01 Z_\odot$, each code results in $\sim 5,000\mbox{--}9,000$ BBHs that merge within a Hubble time. However, $\lesssim 14\%$ of progenitors overlap between two codes, and only $\textit{one}$ initial binary becomes a BBH merger across all three codes. Identical progenitors often follow different evolutionary pathways in each code and result in inconsistent BBH properties. Our results highlight the need for a deeper understanding of physical and computational differences between BPS codes and caution against over-interpreting results from any individual BPS code.
[abstract 34 / 46] (score: 2) - Title: Elastic toroidal vector DARK MATTER through a dark photon in the LUX-ZEPLIN high recoil windowAuthors: Imtiaz Khan, Salvatore Capozziello, G. Mustafa, Farkhod Botirov, Ahmadjon Abdujabbarov, Farruh Atamurotov, Phongpichit Channuie,Comments: 13 pages, 10 figuresSubjects: hep-phCreated: 2026-09-20; Updated: 2026-09-23; Datestamp: 2026-09-23
The 2026 LUX-ZEPLIN search reports one nuclear recoil candidate at $248\pm23_{\rm stat}\pm23_{\rm sys}~\mathrm{keV}$ in an extended window reaching about $270~\mathrm{keV}$. We consider elastic scattering of neutral complex vector DARK MATTER through its dimension-six toroidal electroMAGNETic moment and find appreciable spectral weight in this recoil region. The nonRELATIVISTIC reduction correlates $\mathcal O_{17}$ and $\mathcal O_{20}$, relating a coherent charge branch to a transverse spin tensor branch. For $m_X=1~\mathrm{TeV}$, natural xenon exhibits a broad high recoil maximum at $204.8$ to $206.6~\mathrm{keV}$ and retains $80.4$ to $85.4\%$ of this maximum at $248~\mathrm{keV}$. Resolving the interaction through a dark photon relates the high-to-low recoil ratio to the mediator mass. A renormalizable $SU(2)_X\times U(1)_D$ realization stabilizes the complex vector by a residual $Z_3$ gauge symmetry and generates the toroidal current through vectorlike messengers carrying a physical CP phase. For a benchmark with $m_X=0.998~\mathrm{TeV}$ and $m_{A'}=0.450~\mathrm{GeV}$, $R(248)/R(50)=1.43$ for GCN and $1.21$ for JJ55, while the odd $A$ xenon fraction remains above $99.9\%$. The response level ratio between the $350$ to $590~\mathrm{keV}$ and $100$ to $270~\mathrm{keV}$ intervals is about $0.46$ at this benchmark. The tensor branch is absent for spin zero argon, whereas annual modulation remains at the few percent level. The resulting spectral, isotope, target, timing, mediator, and high energy dependences give correlated tests of an elastic tensor interpretation of the LZ recoil.
[abstract 35 / 46] (score: 2) - Title: Reconnection of Gravitational FieldsAuthors: Luca Comisso, Felipe A. Asenjo,Comments: To appear in Physical Review DSubjects: gr-qc astro-ph.HE hep-thCreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
In a tetrad formulation of general relativity, an ideal Ohm-type condition for the gravitational field implies the conservation of gravitational fluxes and the preservation of the connectivity of gravitational field sheets. We investigate the consequences of departures from ideal gravitational evolution by developing a theory of gravitational RECONNECTion, defined as a change in the connectivity of gravitational field sheets arising from the breakdown of the ideal frozen-in evolution of the gravitational field. We derive quantitative measures of the gravitational RECONNECTion rate, show that gravitational RECONNECTion alters the energy-momentum exchange between the gravitational and matter sectors, and determine how it modifies the evolution of gravitational helicity. Our results provide a quantitative framework for describing changes in gravitational connectivity and their consequences in dynamical spacetimes.
[abstract 36 / 46] (score: 2) - Title: First Trigonometric Parallax Measurements with the KVN and VERA Array (KaVA)Authors: Nobuyuki Sakai, Daisuke Sakai, Noriyuki Kawaguchi, Shuangjing Xu, Bo Zhang, Taehyun Jung, Chungsik Oh, Jeong-Sook Kim, Soon-Wook Kim, Hiroshi Imai, Yuanwei Wu, Maria Rioja, Niu Liu, Zehao Lin, Ibnu Nurul Huda, Shuaibo Bian, Leonid Petrov, Jingdong Zhang, Takaaki Jike, Yoshiaki Tamura, Jeong Ae Lee, Hao Ding, Koichiro Sugiyama, Kazuhiro Hada, Kiyoaki Wajima, Kazuya Hachisuka, Mareki Honma, Kee-Tae Kim, Se-Jin Oh,Comments: Accepted for publication in PASJ. DOI: https://doi.org/10.1093/pasj/psag117Subjects: astro-ph.GACreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
To demonstrate the astrometric capability of the combined Korean VLBI (Very Long Baseline Interferometry) Network (KVN) and VLBI Exploration of Radio Astrometry (VERA) Array (KaVA), we conducted six-epoch VLBI observations of 22-GHz H$_{2}$O masers associated with the star-forming region W3(OH). Two atmospheric calibration methods, (1) GPS and (2) JMA (Japan Meteorological Agency) mesoscale analysis data, and two phase-reference sources were independently applied to the astrometric analysis. Trigonometric parallaxes of W3(OH) were successfully measured with all calibration strategies, including the first successful parallax measurement using JMA calibration. The combined-fit parallax is 0.497$\pm$0.024 mas, corresponding to a distance of 2.01$^{+0.10}_{-0.09}$ kpc. This value is consistent with the previous Very Long Baseline Array (VLBA) result of 0.489$\pm$0.017 mas. KaVA achieved a 55$\%$ higher signal-to-noise ratio in phase-referenced maps than VERA, in good agreement with theoretical expectations. These results suggest that KaVA will enable trigonometric parallax measurements of 22-GHz H$_2$O masers that are difficult to observe with VERA alone because of low flux densities and/or limited $uv$ coverage. A flux variation from 510\,$\pm$\,50 to 3900\,$\pm$\,400 Jy was detected in W3(OH) over a one-year observing campaign and is attributed to two nearby maser features separated by only $\sim$64 AU at 2.01 kpc. The brightest feature showed a decrease in linewidth with increasing peak flux density, consistent with unsaturated maser amplification, whereas no similar trend was found for the other feature, suggesting different responses to the same amplification conditions, possibly owing to differences in saturation state and internal velocity structure.
[abstract 37 / 46] (score: 2) - Title: SALVAGE II: no systematic molecular gas depletion in the central 2 kpc of AGN hostsAuthors: Scott Wilkinson, Chiara Circosta, Toby Brown, Sara L. Ellison, Shoshannah Byrne-Mamahit, Almudena Alonso-Herrero, Santiago Garcia-Burillo, Federico Esposito,Comments: 20 pages, 11 figures, accepted by MNRASSubjects: astro-ph.GACreated: 2026-09-21; Updated: 2026-09-23; Datestamp: 2026-09-23
In cosmological simulations, ACTIVE GALACTIC NUCLEi (AGN) feedback is found to be necessary for the shutdown of galaxy-wide star-formation by heating and/or removing molecular gas. However, at low-redshift, there is little evidence of systematic large-scale gas depletion. Some recent observations have found molecular gas depletion in AGN hosts, but limited to the central regions of galaxies. In this work, we use the SDSS-ALMA Legacy-Value Archival Gas Exploration (SALVAGE) dataset, which provides molecular gas and stellar mass measurements from the inner (r < 0.5-2 kpc) and outer region of the galaxy. Using AGN diagnostics from optical emission lines, mid-IR colour, and X-ray luminosity, we identify 70 AGN at z < 0.07 and inspect their central molecular gas reservoirs with a suite of metrics compared to non-AGN controls. In agreement with global studies of low-z AGN hosts, we find that, compared to matched non-AGN, the central regions of AGN have equal molecular gas fractions and enhanced molecular gas surface densities. For the first time, we explore the central gas reservoirs of AGN identified with different selection criteria and find two optical AGN classes that show a tentative 1.5$σ$ and 1.8$σ$ signal of central molecular gas depletion. However, the AGN with central gas depletion do not occupy any specific region of the parameter space, such as AGN luminosity, that can provide a physical explanation for the depletion. If AGN are responsible for large-scale gas removal, the lack of systematic gas depletion in SALVAGE AGN sets an upper limit on the physical scale of the gas removal while the AGN remains observable.
[abstract 38 / 46] (score: 2) - Title: Probing the Mass--Redshift Dependence of Binary Black Holes and its Implications for $H_0$ with GWTC-5.0Authors: Yang Liu, Puxun Wu, Jun-Jie Wei, Xue-Feng Wu,Comments: 22 pages, 4 figures, 2 tablesSubjects: astro-ph.CO astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
The mass and redshift distributions of merging binary BLACK HOLEs (BBHs) bear imprints of their astrophysical formation channels. Whether the BH mass distribution evolves with redshift, however, remains an open question. In this paper, we employ copula functions, which describe the dependence between variables independently of their marginal distributions, to probe the dependence structure between the primary mass and the redshift of BBH mergers. We construct five population models by coupling the marginal distributions of primary mass and redshift with the Gaussian copula, the Clayton copula, or one of its three rotations, and we constrain their hyperparameters using 235 BBH events from GWTC-5.0. For comparison, we also adopt a baseline model in which the primary mass and redshift are assumed independent. Among the copula-based models, only the model with the $180^\circ$ rotated Clayton copula, which couples higher primary masses preferentially with high redshifts, exhibits evidence for a nonzero correlation, with its copula parameter deviating from the independence limit at more than $1σ$ significance. Importantly, the constraints on the Hubble constant ($H_0$) derived from these models are mutually consistent within the $68\%$ confidence level; the baseline model yields $H_0=74.3^{+13.7}_{-19.6}~\mathrm{km\ s^{-1}\ Mpc^{-1}}$, indicating that allowing for a mass--redshift dependence does not significantly bias the $H_0$ inference with the current dataset. Bayesian model comparison favors the baseline model over all copula-based alternatives, with log-Bayes factors corresponding to weak to moderate evidence against the latter on the Jeffreys scale. Our results thus imply that the current GWTC-5.0 sample remains consistent with no redshift evolution of the primary mass distribution over the redshift range probed.
[abstract 39 / 46] (score: 2) - Title: Lensing Signatures of a Primary Hair Black Hole SolutionAuthors: Rahul Das, Umananda Dev Goswami,Comments: 20 pages, 15 figuresSubjects: gr-qcCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We investigate the weak and strong field gravitational lensing of light by a primary hair BLACK HOLE (BH) solution obtained within the framework of the gravitational decoupling (GD) approach. In this method, the BH solution is constructed by introducing geometric deformations to a known seed spacetime, which, in the present case, is the Schwarzschild geometry. The deformation functions are determined by imposing the dominant energy condition, leading to the emergence of two characteristic parameters, the primary hair $Q$ and the coupling constant $α$, both of which deform the Schwarzschild spacetime. To explore the lensing properties of this BH, we employ the Gibbons-Werner approach in the weak field regime and Bozza's formalism in the strong field regime. In the weak field limit, we derive the deflection angle up to second-order corrections and find that the coupling parameter $α$ contributes more significantly to the leading-order deflection than the primary hair parameter $Q$. The primary hair is also found to exhibit an effectively repulsive gravitational behavior. In the strong field regime, we compute the deflection angle of photons propagating near the photon sphere, where the deflection diverges logarithmically, allowing photons to complete multiple loops around the BH and form RELATIVISTIC images. Using the supermassive BH Sgr A* as the astrophysical lens, we further investigate the strong lensing observables, namely the asymptotic angular position $\vartheta_{\infty}$, the angular separation $s$, and the relative magnitude $r_{\mathrm{mag}}$. We also constrain the primary hair parameter $Q$ for different values of the coupling constant $α$ using the shadow observations of Sgr A* reported by the Event Horizon Telescope (EHT) Collaboration.
[abstract 40 / 46] (score: 2) - Title: Dense Dump Codec: Error-Controlled, Random-Access Compression of GRMHD Time Series for Slow-Light Radiative TransferAuthors: Zelin Zhang, Zhenyu Zhang, Bin Chen,Comments: 13 pages, 5 figures, 4 TablesSubjects: astro-ph.HE gr-qcCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Black-hole movies provide a unique venue to study the time evolution of accreting plasma. Modeling this evolution with slow-light radiative transfer requires closely spaced simulation outputs, because the plasma changes as light propagates through it. Saving these outputs in full is costly, whereas sparse sampling introduces time-interpolation errors. We present the Dense Dump Codec (DDC), a compression method for dense GRMHD time series. DDC stores exact anchor states and compactly represents the intermediate evolution, while allowing direct access to selected times and variables. Applied to eight production sequences spanning SANE and MAD simulations at several black-hole spins with 0.1M output, DDC archives are about 10 times smaller than the original dense data and even about 50% smaller than the original 0.5M output in aggregate. We further integrate a native DDC reader into polarized slow-light radiative transfer. Tests at 86, 230, and 345 GHz show that DDC may reduce aggregate Stokes-image errors by 54-79% relative to slow-light calculations using original 0.5M input. These results indicate that DDC enables high-cadence slow-light calculations without the prohibitive cost of saving every dense GRMHD state in its original form.
[abstract 41 / 46] (score: 2) - Title: Transport and Thermochemical Kinetics of Alkali Species in Hot Jupiter Atmospheres: Implications for Magnetic ModelsAuthors: D. A. Christie, T. M. Evans-Soma, N. J. Mayne, E. Hébrard, M. Zamyatina, J. E. Owen, K. Kohary,Comments: 29 pages, 33 figures. Accepted to MNRASSubjects: astro-ph.EPCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Interactions between the planetary MAGNETic field of a hot Jupiter and the winds within its atmosphere are moderated by the electron and ion abundances. For a solar metallicity atmosphere at pressures between 10 and $10^{-4}$ bar, the primary sources for these charged species are expected to be the potassium and sodium atoms, and models of MAGNETic effects in hot Jupiter atmospheres have typically assumed that charged species exist within the atmosphere in their equilibrium abundances. In this work, we investigate the thermochemical kinetics of alkali species within a hot Jupiter atmosphere, thus allowing for the thermal ionisation fraction to depart from equilibrium, and demonstrate that quenching of ions occurs between 1 and 10 mbar. This increase in ionisation fraction on the nightside and at mid-latitudes results in stronger MAGNETic interaction, here modelled using the MAGNETic drag approximation, further slowing the JET and altering the global circulation. We additionally show that while quenching occurs, large MAGNETic resistivities resulting from low electron abundances continue to exist on the nightside between 10 and 100 mbar, in tension with MAGNETohydrodynamic models that assume horizontally uniform MAGNETic resistivities to simplify the explicit integration of the induction equation. At lower pressures ($\sim$ 0.1 mbar) where the electrons have become horizontally homogenised, the MAGNETic Reynolds number approaches or exceeds unity, signalling the breakdown of the MAGNETic drag approximation. We thus stress that chemical kinetics represents a dynamically important component of modelling hot Jupiter atmospheres while at the same time further complicating the treatment of MAGNETic effects.
[abstract 42 / 46] (score: 2) - Title: Neutrino Astronomy at High Energies - An Experimental ReviewAuthors: Christian Spiering,Comments:Subjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Neutrino astronomy at high energies is an emerging field but still in a state of infancy. It is barely a dozen years ago that a diffuse flux of extraterrestrial neutrinos with energies in the TeV and PeV ranges was detected and even fewer that first individual sources could be identified. A new window to the universe has been opened after four decades of efforts to realize the gigantic instruments that made that breakthrough possible. This review describes the road towards the present, reviews the actual status of the field and sketches future developments.
[abstract 43 / 46] (score: 2) - Title: A VLBA survey of radio stars in the Orion Nebula Cluster: III. Inter-epoch variability analysisAuthors: E. T. O'Kelly, J. Forbrich, S. A. Dzib, J. Vargas-González,Comments: 31 pages, 7 main figures, 2 figures in appendicesSubjects: astro-ph.SRCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We present a multi-epoch Very Long Baseline Array (VLBA) survey of radio sources in the Orion Nebula Cluster (ONC), updating the detection statistics and investigating inter-epoch variability. The dataset comprises eight C-band (4-8 GHz) epochs targeting 575 radio sources previously identified in deep Very Large Array surveys. VLBA observations result in resolutions of milliarcseconds and are only sensitive to high brightness temperatures meaning only non-thermal emission is observed. We detect 226 unique radio sources corresponding to a detection fraction of 39 per cent. The majority of sources (~83 per cent) are detected only once indicating that non-thermal emission associated with Young Stellar Objects (YSOs) is highly intermittent. To quantify variability, we use per-epoch peak flux densities and the variability factor (VF) defined as the ratio between the maximum and minimum fluxes. We identify 21 sources (~9 per cent of detected sources) that exhibit high variability defined as a change of flux density by at least a factor of five. We crossmatch with the COUP Chandra survey to identify sources as YSOs. We identify COUP counterparts for ~56 per cent of the detected sources. The remaining population cannot be explained solely by variability or background contamination, suggesting a population of radio detected YSOs without X-ray counterparts. We find a clear correlation between radio and X-ray luminosities consistent with the Güdel-Benz relation, the empirical relation between non-thermal radio and thermal X-ray emission for MAGNETically active stars.
[abstract 44 / 46] (score: 2) - Title: Exploring the influence of reionisation-era galaxies on their local intergalactic medium using the Sherwood-Relics simulationsAuthors: Hamish Anderson, Laura C. Keating, Luke Conaboy, Xiangyu Jin, James S. Bolton, Ewald Puchwein,Comments: 13 pages, 8 figuresSubjects: astro-ph.GACreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
Recent surveys have detected excess flux in the Lyman-$α$ forest of QUASAR spectra several Mpc from high-redshift line-emitting galaxies, indicating a correlation between intergalactic medium (IGM) transmission and reionisation-era galaxies. We examine the galaxy-IGM connection using the Sherwood-Relics simulation suite, a set of hybrid radiation-hydrodynamic simulations that model the IGM at high redshift. We simulate the Lyman-$α$ forest and a population of mock [OIII] emitters using the survey specifications of JWST's ASPIRE programme. We measure the evolution of the effective optical depth in regions close to galaxies, and contrast this with a control sample probing the random IGM. We characterise the changing physical properties of the IGM to explain the observed sightline-to-sightline scatter in opacity between 5.4 < $z$ < 6.2. We find that the IGM is more opaque than average at small radii ($r$ $\leq$ 5 cMpc/$h$) close to galaxies, as these regions are overdense. At larger radii (15 < $r$ $\leq$ 50 cMpc/$h$), the IGM is more ionised than average, due to the higher photoionisation rate near galaxies. We find qualitative agreement with the observational results from ASPIRE, though we see large realisation-to-realisation scatter driven by cosmic variance, as also seen in theoretical explorations of the galaxy-Ly$α$ transmission cross-correlation function. Our results generally agree with observations claiming that there is a large-scale ionisation bias around [OIII] emitters, supporting the idea that their role is significant in shaping the properties of the IGM during reionisation.
[abstract 45 / 46] (score: 2) - Title: Gravitational-Susceptibility Dip Behind DESI's results: Addressing the Phantom Crossing by Local limit of Nonlocal GravityAuthors: Aria Hemmatian, Yahya Mohammadi, Javad Tabatabaei, Shant Baghram,Comments: 11 pages, 4 figures, 2 tables, submitted to MNRASSubjects: astro-ph.CO gr-qcCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
The second data release of the Dark Energy Spectroscopic Instrument (DESI), based on more than fourteen million galaxies and QUASARs, prefers a DARK ENERGY component whose equation of state is dynamical. In the simplest two-parameter description of this behavior, the Chevallier--Polarski--Linder (CPL) parametrization, the data favor the quadrant $w_0>-1$, $w_a<0$, which implies that the equation of state crosses the phantom divide $w=-1$ at a redshift $z\simeq0.4$. We show that the local limit of nonlocal gravity, a teleparallel extension of general relativity governed by a scalar function called gravitational susceptibility $S(x)$, offers a natural explanation. In this model a cosmological constant is not allowed; DARK ENERGY is necessarily dynamical. The phantom crossing seen by an observer is an effective phenomenon generated by the time evolution of $S(z)$. We establish a correspondence: to every general-RELATIVISTIC DARK ENERGY model with equation of state $w(z)$, there corresponds a modified TEGR cosmology with $w=-1$ and a suitable susceptibility $S(z)$ that are indistinguishable at the level of the background expansion. We construct the susceptibility functions that reproduce the CPL behavior favored by DESI data, and we confront the model with the combined CMB,BAO, and SNe data using Boltzmann solver codes. The recovered susceptibility displays a characteristic low-redshift dip with depth $β= -0.025 \pm 0.007$ at $z\simeq 0.4 $, and its derivative changes sign at a redshift equal to the phantom-crossing epoch.
[abstract 46 / 46] (score: 2) - Title: The First Blind Survey of Intervening NaI Absorbers: Incidence and Cosmic Evolution with DESIAuthors: Abhijeet Anand, Sowgat Muzahid,Comments: Submitted to AAS journalsSubjects: astro-ph.GA astro-ph.COCreated: 2026-09-22; Updated: 2026-09-23; Datestamp: 2026-09-23
We present the first blind statistical survey of intervening NaI absorbers over the last $\simeq3$~Gyr using QUASAR spectra from the Dark Energy Spectroscopic Instrument Data Release~1. We identify 3636 NaI D doublets at $0.01\lesssim z_{\rm abs}\lesssim0.27$ along 214,035 QUASAR sightlines. We quantify the survey selection function through end-to-end injection--recovery tests and estimate the residual contamination from visual inspection. The completeness reaches 50% at a rest-equivalent width of the NaI $\lambda5891$ line, $W_{5891}\simeq0.95$ Angstrom, and the catalog-weighted purity is $\simeq77\%$. For the fiducial sample with $0.95
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