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astro-ph.HE2026

A Real-Time Jet Laboratory in Swift J1727.8-1613

Callan M. Wood, James C. A. Miller-Jones, Arash Bahramian +16

We present the results of our intensive VLBI campaign on the black-hole low-mass X-ray binary (LMXB) Swift J1727.8-1613 during its 2023-2024 outburst. We observed the repeated quen…

astro-ph.HE2026

GRB 260310A / SN 2026fgk: A Multi-Wavelength Study of a Nearby Underluminous Long GRB and SN with a Complex Afterglow

Ramandeep Gill, Rosa L. Becerra, Antonio de Ugarte Postigo +54

We present a comprehensive multi-wavelength study of GRB 260310A / SN 2026fgk, a nearby (), long-duration gamma-ray burst (GRB) with an exceptionally underluminous prompt…

astro-ph.HE2026★ 1 cited

GRB 210704A: A Luminous Fast Blue Transient in a GRB Afterglow at

Daniëlle L. A. Pieterse, Andrew J. Levan, Maria E. Ravasio +27

We present detailed, multi-wavelength analysis of GRB 210704A: a Fermi Gamma-ray Burst Monitor discovered and Fermi Large Area Telescope (LAT) detected gamma-ray burst (GRB). The b…

astro-ph.HE2026

The Northern High Time Resolution Universe pulsar survey: III. Single-pulse search continuation, follow-up observations, and initial results

L. J. M. Houben, H. Falcke, L. G. Spitler +5

We continued the search for single pulses (SPs) in the northern part of the all-sky High Time Resolution Universe survey, whose aim is to detect pulsars and other radio transients.…

astro-ph.HE2026

A Bayesian Method for Air-Shower Reconstruction using Information Field Theory

Karen Terveer, Sjoerd Bouma, Stijn Buitink +12

The radio detection of extensive air showers provides a powerful method for studying the origin of high-energy cosmic rays. The Low-Frequency Array (LOFAR) offers unprecedentedly d…

astro-ph.HE2026

Las Cumbres Observatory Gravitational-Wave Follow-up in the Third and Fourth Observing Runs: Strengths and Weaknesses of a Rapid Response Galaxy Targeted Strategy

Ido Keinan, Iair Arcavi, D. Andrew Howell +34

We present a summary of gravitational-wave (GW) follow-up using the Las Cumbres Observatory global network of telescopes during the third (O3) and fourth (O4) observing runs of the…

astro-ph.HE2026

A search for optical counterparts in quiescent black hole X-ray transients

I. V. Yanes-Rizo, J. Casares, M. A. P. Torres +7

Dynamical mass measurements of compact stars in X-ray transients demand the detection of optical/near infrared counterparts in quiescence. Out of the 73 black-hole candidates in X-…

astro-ph.HE2026★ 1 cited

Rapid jet ejection from PKS 0215+015 coincident with a high-energy neutrino event

F. Eppel, M. Kadler, E. Ros +19

Aims. We present a new neutrino-blazar multiwavelength flare coincidence observed in the blazar PKS 0215+015, which showed a strong multiwavelength outburst in coincidence with the…

astro-ph.HE2026

Survey of compact sources for pulsars and exotic objects -- I. Overview and initial discoveries

Yogesh Maan, Apurba Bera, Dharam Vir Lal +4

Targeted searches for pulsars based on their counterparts in radio images have resulted in the discovery of interesting pulsars including the first ever discovered millisecond puls…

astro-ph.HE2026

GOTO identification and broadband modelling of the counterpart to the SVOM GRB 250818B

S. Belkin, G. P. Lamb, K. Ackley +61

Rapid localisation and follow-up of gamma-ray bursts (GRBs) increasingly rely on low-latency triggers from new missions coupled to wide-field robotic optical facilities. We present…

astro-ph.HE2026

A Faint Progenitor System for the Faint Supernova 2024vjm

Erez A. Zimmerman, Avishay Gal-Yam, Paul J. Groot +68

Type Ia Supernovae (SNe Ia) are well known for their role as standardizable cosmological candles. Their uniformity is credited to their single origin as thermonuclear explosions of…

astro-ph.HE2026

Identifying Host Galaxies of Binary Black Hole Mergers with Next-Generation Gravitational Wave Detector Networks

Sumedha Biswas, Andrew Levan, Peter G. Jonker +3

Identifying the host galaxy of a binary black hole (BBH) merger detected via gravitational waves (GWs) remains a challenge due to the absence of electromagnetic counterparts and th…

astro-ph.HE2026★ 1 cited

An Archival Optical Counterpart Search for Extragalactic Fast X-Ray Transients Discovered by Einstein Probe

Run-Duo Liang, Wen-Xiong Li, Liang-Duan Liu +50

Extragalactic fast X-ray transients (eFXTs) represent a rapidly growing class of high-energy phenomena, whose physical origins remain poorly understood. With its wide-field, sensit…

astro-ph.HE2026

Search for ultra-high energy neutrons from Galactic sources with the Pierre Auger Observatory

The Pierre Auger Collaboration, A. Abdul Halim, P. Abreu +357

Deflections in the propagation of charged ultra-high-energy cosmic rays (UHECRs) caused by magnetic fields make the identification of their sources challenging. On the other hand,…

astro-ph.HE2026★ 1 cited

Locating the missing large-scale emission in the jet of M87* with short EHT baselines

Boris Georgiev, Paul Tiede, Sebastiano D. von Fellenberg +280

In Very-Long Baseline Interferometric arrays, nearly co-located stations probe the largest scales and typically cannot resolve the observed source. In the absence of large-scale st…

astro-ph.HE2026★ 2 cited

GRB 180728A and SN 2018fip: the nearest high-energy cosmological gamma-ray burst with an associated supernova

A. Rossi, L. Izzo, K. Maeda +29

The long GRB 180728A, at a redshift of , stands out due to its high isotropic energy of erg, in contrast with most events at redshif…

astro-ph.HE2026

Minutes-long soft X-ray prompt emission from a compact object merger

An Li, Chen-Wei Wang, Niccolò Passaleva +75

Compact object mergers are multi-messenger sources and known progenitors of some gamma-ray bursts, bright flashes of high-energy radiation powered by a central engine, either an ac…

astro-ph.HE2025★ 4 cited

Probing jet base emission of M87* with the 2021 Event Horizon Telescope observations

Saurabh, Hendrik Müller, Sebastiano D. von Fellenberg +282

We investigate the presence and spatial characteristics of the jet base emission in M87* at 230 GHz, enabled by the enhanced uv coverage in the 2021 Event Horizon Telescope (EHT) o…

astro-ph.HE2025★ 1 cited

The Faintest, Extremely Variable X-ray Tidal Disruption Event from a Supermassive Black Hole Binary?

Mengqiu Huang, Yongquan Xue, Shuo Li +30

Tidal disruption events (TDEs), which occur when stars enter the tidal radii of supermassive black holes (SMBHs) and are subsequently torn apart by their tidal forces, represent in…

astro-ph.HE2025

Radio properties of the quasi-periodic eruption source RXJ1301.9+2747 at parsec scales

S. D. von Fellenberg, R. Arcodia, P. Benke +6

Quasi-periodic eruptions (QPEs) are repeating soft X-ray flares associated with galactic nuclei. Several recent works have found evidence that the accretion flow in the galactic nu…

astro-ph.HE2025★ 3 cited

Unveiling the nature of the Einstein Probe transient EP 241021a

J. Quirola-Vásquez, P. G. Jonker, A. J. Levan +23

We present a multi-wavelength analysis of the fast X-ray transient EP 241021a, discovered by the Wide-field X-ray Telescope aboard the \emph{Einstein Probe} satellite on 2024 Octob…

astro-ph.HE2025

The most distant optically polarised GRB afterglow: GRB 240419A at z = 5.178

R. Brivio, S. Covino, M. Ferro +31

Gamma-ray bursts (GRBs) are extremely bright phenomena powered by relativistic jets arising from explosive events at cosmological distances. The nature of the jet and the configura…

astro-ph.HE2025★ 1 cited

The metallicity dependence of long-duration gamma-ray bursts

Paul Disberg, Anne Lankreijer, Martyna Chruślińska +5

Both theoretical models and observations of collapsar created gamma-ray bursts -- typically long-duration gamma-ray bursts (LGRBs) -- suggest that these transients cannot occur at…

astro-ph.HE2025

Gamma-ray Bursts

Andrew J. Levan

Gamma-ray bursts are flashes of high-energy radiation lasting from a fraction of a second to several hours. Military satellites made the first detections of GRBs in the late 1960s.…