Issue |
A&A
Volume 696, April 2025
|
|
---|---|---|
Article Number | L8 | |
Number of page(s) | 5 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202453099 | |
Published online | 08 April 2025 |
Letter to the Editor
Intergalactic magnetism in a γ-ray beam as a model of Porphyrion
1
Université Paris Cité, CNRS, Astroparticule et Cosmologie, 75006 Paris, France
2
Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
3
Dipartimento di Fisica e Astronomia, Universita di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
4
INAF Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
5
Nordita, KTH Royal Institute of Technology and Stockholm University, Hannes Alfvéns väg 12, 10691 Stockholm, Sweden
6
The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden
7
McWilliams Center for Cosmology & Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
8
School of Natural Sciences and Medicine, Ilia State University, 3-5 Cholokashvili Avenue, 0194 Tbilisi, Georgia
9
Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, 1211 Geneve 4, Switzerland
10
Theoretical Physics Department, CERN, 1211 Geneva 23, Switzerland
⋆ Corresponding author.
Received:
20
November
2024
Accepted:
24
March
2025
We estimate the magnetic field in the jets of the recently discovered 7 Mpc long Porphyrion system. We used nondetection of the system in gamma-rays to derive a lower bound on the co-moving magnetic field strength at the level of ∼10 nG (comoving). This value is consistent with recent estimates of magnetic fields in the filaments of the large-scale structure. We discuss the possibility that, instead of being the extreme case of a radio jet formation scenario, Porphyrion actually traces a very high-energy γ-ray beam emitted by an active galactic nucleus. In such a model, jets do not need to spread into the voids of the large-scale structure to appear straight on a very large distance range, and several anomalies of the standard radio jet scenarios can be solved at once.
Key words: magnetic fields / galaxies: active / galaxies: jets / large-scale structure of Universe / gamma rays: galaxies / radio lines: galaxies
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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