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19912026
Showing astro-ph.HEShow all

263 papers · 1 filter

astro-ph.HE2026

A Ring of Fire Orphan γ-Ray Flare in the Neutrino Candidate 3C 120

E. Traianou, G. Bruni, J. Rodi +7

We present 43\,GHz VLBI observations of the radio galaxy 3C~120 during its brightest -ray outburst (March 2018), recently associated with the IceCube neutrino alert IC-180213A.…

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★ 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

The DESI Transients Survey: Legacy Classifications and Methodology

Xander J. Hall, Antonella Palmese, Segev BenZvi +56

We present the first systematic spectroscopic observations of extragalactic transients from the Dark Energy Spectroscopic Instrument (DESI), as part of the DESI Transients Survey p…

astro-ph.HE2026

A long-term multiwavelength study of the flat spectrum radio quasar OP 313

Chiara Bartolini, Elina Lindfors, Andrea Tramacere +25

The Flat Spectrum Radio Quasar OP 313 is a high-redshift (z = 0.997) blazar that entered an intense gamma-ray active phase from November 2023 to March 2024, as observed by the Larg…

astro-ph.HE2026

Early results in the search for extreme coronal line emitters with the Dark Energy Spectroscopic Instrument

Peter Clark, Joseph Callow, Or Graur +44

Here we present the results of our search through the Early Data Release (EDR) of the Dark Energy Spectroscopic Instrument (DESI) for extreme coronal line emitters (ECLEs) - a rare…

astro-ph.HE2026★ 2 cited

First detection of VHE gamma-ray signal from the FSRQ TON 0599

MAGIC Collaboration, K. Abe, S. Abe +245

TON\,0599 (z=0.7247) belongs to the few flat spectrum radio quasars (FSRQs) detected in the very high energy (VHE, \,GeV) gamma-ray band. Its redshift makes it currently o…

astro-ph.HE2025★ 3 cited

Multiband optical variability on diverse timescales of the blazar Ton 599 from 2011 to 2023

O. Vince, C. M. Raiteri, M. Villata +72

(Shortened)Context: We analyze the optical variability of the FSRQ Ton 599 using BVRI photometry from the WEBT collaboration (2011-2023), complemented by photometric and spectrosco…

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★ 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

Polarization of reflected X-ray emission from the Sgr A molecular complex: multiple flares, multiple sources?

Ildar Khabibullin, Eugene Churazov, Riccardo Ferrazzoli +100

The extended X-ray emission observed in the direction of several molecular clouds in the central molecular zone of our Galaxy exhibits spectral and temporal properties consistent w…

astro-ph.HE2025★ 9 cited

Determining the origin of the X-ray emission in blazars through multiwavelength polarization

Ioannis Liodakis, Haocheng Zhang, Stella Boula +48

The origin of the high-energy emission in astrophysical jets from black holes is a highly debated issue. This is particularly true for jets from supermassive black holes that are a…

astro-ph.HE2025★ 4 cited

Origin of the ring ellipticity in the black hole images of M87*

Rohan Dahale, Ilje Cho, Kotaro Moriyama +273

We investigate the origin of the elliptical ring structure observed in the images of the supermassive black hole M87*, aiming to disentangle contributions from gravitational, astro…

astro-ph.HE2025★ 8 cited

X-ray Polarization of the High-Synchrotron-Peak BL Lacertae Object 1ES 1959+650 during Intermediate and High X-ray Flux States

Luigi Pacciani, Dawoon E. Kim, Riccardo Middei +97

We report the Imaging X-ray Polarimetry Explorer (IXPE) polarimetric and simultaneous multiwavelength observations of the high-energy-peaked BL Lacertae (HBL) object 1ES 1959+650,…

astro-ph.HE2025★ 7 cited

AT 2018dyk: tidal disruption event or active galactic nucleus? Follow-up observations of an extreme coronal line emitter with the Dark Energy Spectroscopic Instrument

Peter Clark, Joseph Callow, Or Graur +29

We present fresh insights into the nature of the tidal disruption event (TDE) candidate AT 2018dyk. AT 2018dyk has sparked a debate in the literature around its classification as e…

astro-ph.HE2025★ 10 cited

The putative center in NGC 1052

Anne-Kathrin Baczko, Matthias Kadler, Eduardo Ros +284

Many active galaxies harbor powerful relativistic jets, however, the detailed mechanisms of their formation and acceleration remain poorly understood. To investigate the area of je…

astro-ph.HE2025★ 2 cited

The polarisation behaviour of OJ 287 viewed through radio, millimetre and optical observations between 2015 and 2017

J. Jormanainen, T. Hovatta, E. Lindfors +13

OJ 287 is a bright blazar with century-long observations, and one of the strongest candidates to host a supermassive black hole binary. Its polarisation behaviour between 2015 and…

astro-ph.HE2024★ 1 cited

Time-dependent modelling of short-term variability in the TeV-blazar VER J0521+211 during the major flare in 2020

MAGIC Collaboration, S. Abe, J. Abhir +228

The BL Lacertae object VER J0521+211 underwent a notable flaring episode in February 2020. A short-term monitoring campaign, led by the MAGIC (Major Atmospheric Gamma Imaging Chere…

astro-ph.HE2024★ 5 cited

Evolution, speed, and precession of the parsec-scale jet in the 3C 84 radio galaxy

M. Foschi, J. L. Gómez, A. Fuentes +3

We present high resolution images of the radio source 3C 84 at 43 GHz, from 121 observations conducted by the BEAM-ME monitoring program between 2010 and 2023. Imaging was performe…

astro-ph.HE2024★ 4 cited

Multi-wavelength study of OT 081: broadband modelling of a transitional blazar

MAGIC Collaboration, H. Abe, S. Abe +270

OT 081 is a well-known, luminous blazar that is remarkably variable in many energy bands. We present the first broadband study of the source which includes very-high-energy (VHE, $…

astro-ph.HE2024★ 10 cited

IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare

Pouya M. Kouch, Ioannis Liodakis, Francesco Fenu +134

The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets…

astro-ph.HE2024★ 15 cited

A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour

C. M. Raiteri, M. Villata, M. I. Carnerero +96

Blazars are beamed active galactic nuclei known for their strong multi-wavelength variability on timescales from years down to minutes. We aim to investigate the suitability of the…

astro-ph.HE2024★ 7 cited

Insights from the first flaring activity of a high-synchrotron-peaked blazar with X-ray polarization and VHE gamma rays

MAGIC Collaboration, K. Abe, S. Abe +250

We study a flaring activity of the HSP Mrk421 that was characterized from radio to very-high-energy (VHE; E TeV) gamma rays with MAGIC, Fermi-LAT, Swift, XMM-Newton and sever…

astro-ph.HE2024★ 5 cited

Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations

Ioannis Liodakis, Sebastian Kiehlmann, Alan P. Marscher +44

Variability can be the pathway to understanding the physical processes in astrophysical jets, however, the high-cadence observations required to test particle acceleration models a…