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astro-ph.HE2026

X-Ray Observation of Type II Supernova 2024ggi

Elisa J. Gao, Vikram V. Dwarkadas

We investigate the Chandra and XMM-Newton X-ray emission from the core-collapse SN 2024ggi. Spectral fitting is carried out using the vapec model. We find X-ray temperatures betwee…

astro-ph.HE2026

Legacy analysis of Milky Way dwarf spheroidal satellite galaxies: an update

A. Circiello, M. Di Mauro, M. Ajello +3

Studies of Fermi-Large Area Telescope (LAT) data coincident with dwarf spheroidal satellite galaxies (dSphs) of the Milky Way (MW) have put the most stringent constraints on models…

astro-ph.HE2026

Chasing Gamma-Ray Signals from Binary Neutron Star Coalescences with the Cherenkov Telescope Array: Prospects and Observing Strategies

S. Abe, J. Abhir, A. Abhishek +457

The detection of gravitational waves (GWs) from a binary neutron star (BNS) merger by Advanced LIGO and Advanced Virgo (GW170817), together with its electromagnetic counterpart, th…

astro-ph.HE2026

The major cluster merger in Abell 2034 as seen by XRISM: Strong turbulence and spectral anomalies?

Annie Heinrich, Irina Zhuravleva, Eugene Churazov +5

XRISM observations to date have shown that gas kinetic pressures in the intracluster medium (ICM) tend towards the low end of predictions from cosmological simulations. Here, we pr…

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

Implications of low neutron star merger rates for gamma-ray bursts, r-process production and Galactic double neutron stars

Maya Fishbach, Alexander P. Ji, Wen-fai Fong +4

The first multimessenger discovery of a binary neutron star (BNS) merger, GW170817, proved that such mergers can source short gamma-ray bursts (SGRBs) and produce r-process element…

astro-ph.HE2026★ 1 cited

Accurate Determination of Chemical Abundances near a Supermassive Black Hole

The XRISM collaboration

The metal abundances in galactic nuclei carry key information on the history of star formation and mass transfer in central regions of galaxies. X-ray fluorescence analysis is a un…

astro-ph.HE2026

Where within the 3C 84 jet are -rays produced?

Georgios F. Paraschos, Ioannis Liodakis, Svetlana Jorstad +49

The location of -ray creation and emission within extra-galactic jets is a matter of active debate. One particularly well-suited source to pinpoint the location is the nearby, b…

astro-ph.HE2026

Resonant scattering at the center of the galaxy cluster PKS 0745-191 with XRISM

Keita Tanaka, Megan Eckart, Kotaro Fukushima +11

We report evidence for the resonant scattering effect at the center of the galaxy cluster PKS 0745-191 with XRISM. We analyzed XRISM/Resolve commissioning-phase observations of the…

astro-ph.HE2026★ 2 cited

High Spectral Resolution X-ray Observations of the Evolved Supermassive Stellar Binary System Carinae - Iron K Band Profile Revealed with XRISM

XRISM Collaboration, Marc Audard, Hisamitsu Awaki +138

The supermassive binary system, Carinae, is experiencing enormous wind-driven mass loss at a rate unparalleled in the rest of the Galaxy. Their wind-wind collision (WWC) contin…

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

A simple model for extracting astrophysics from black hole images

Alexandra G. Guerrero, Daniel E. Holz

The Event Horizon Telescope (EHT) is providing unprecedented high-resolution images of supermassive black holes. These images are fundamentally related to properties of the luminou…

astro-ph.HE2026

McFACTS. IV. Electromagnetic Counterparts to AGN-disk-embedded Binary Black Hole Mergers

Emily McPike, Rosalba Perna, K. E. Saavik Ford +10

The accretion disks of active galactic nuclei (AGNs) are promising environments for producing binary black hole (BBH) mergers, which have been detected via gravitational waves (GWs…

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★ 1 cited

Analysis of 14 Years of X-Ray Emission From SN 2011DH

Elisa J. Gao, Vikram V. Dwarkadas

Ejecta from core-collapse supernovae interact with the circumstellar medium shed by the progenitor star, producing X-ray emission. Previous studies analyzed the X-ray spectrum of t…

astro-ph.HE2025★ 5 cited

Chlorine and Potassium Enrichment in the Cassiopeia A Supernova Remnant

XRISM collaboration

The elements in the universe are synthesized primarily in stars and supernovae, where nuclear fusion favors the production of even-Z elements. In contrast, odd-Z elements are less…

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

XRISM Spectroscopy of the Stellar-mass Black Hole GRS 1915+105

Jon M. Miller, Liyi Gu, John Raymond +11

GRS 1915105 was the stellar-mass black hole that best reproduced key phenomena that are also observed in Type-1 active galactic nuclei. In recent years, however, it has evolved…

astro-ph.HE2025

Deep Learning Analysis of Ions Accelerated at Shocks

Paxson Swierc, Damiano Caprioli, Luca Orusa +1

We study the application of deep learning techniques to the analysis and classification of ions accelerated at collisionless shocks in hybrid (kinetic ions--fluid electrons) simula…

astro-ph.HE2025★ 2 cited

Acceleration of Heavy Ions at Non-Relativistic Collisionless Shocks

Damiano Caprioli, Luca Orusa, Miha Cernetic +2

We investigate the process of Diffusive Shock Acceleration (DSA) of particles with mass number to charge number ratios , e.g., partially-ionized heavy ions. To this end, w…

astro-ph.HE2025★ 5 cited

Mapping the Perseus Galaxy Cluster with XRISM: Gas Kinematic Features and their Implications for Turbulence

Congyao Zhang, Irina Zhuravleva, Annie Heinrich +19

In this paper, we present extended gas kinematic maps of the Perseus cluster by combining five new XRISM/Resolve pointings observed in 2025 with four Performance Verification datas…

astro-ph.HE2025★ 4 cited

Observation of In-ice Askaryan Radiation from High-Energy Cosmic Rays

ARA Collaboration, N. Alden, S. Ali +74

We present the first experimental evidence for in-ice Askaryan radiation -- coherent charge-excess radio emission -- from high-energy particle cascades developing in the Antarctic…

astro-ph.HE2025★ 20 cited

Horizon-scale variability of M87* from 2017--2021 EHT observations

The Event Horizon Telescope Collaboration

We report three epochs of polarized images of M87* at 230\,GHz using data from the Event Horizon Telescope (EHT) taken in 2017, 2018, and 2021. The baseline coverage of the 2021 ob…

astro-ph.HE2025

Efficient Particle Acceleration in 2.5-Dimensional, Hybrid-Kinetic Simulations of Decaying, Supersonic, Plasma Turbulence

Keyan Gootkin, Colby Haggerty, Damiano Caprioli +1

Collisionless, turbulent plasmas surround the Earth, from the magnetosphere to the intergalactic medium, and the fluctuations within them affect nearly every field in the space sci…