The evolution of cosmic ray electrons in the cosmic web: seeding by AGN, star formation and shocks

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Main Authors: Vazza, F., Gheller, C., Zanetti, F, Tsizh, M., Carretti, E., Mtchedlidze, S., Brueggen, M.
Format: Preprint
Published: 2025
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author Vazza, F.
Gheller, C.
Zanetti, F
Tsizh, M.
Carretti, E.
Mtchedlidze, S.
Brueggen, M.
author_facet Vazza, F.
Gheller, C.
Zanetti, F
Tsizh, M.
Carretti, E.
Mtchedlidze, S.
Brueggen, M.
contents Several processes in the Universe convert a fraction of gas kinetic energy into the acceleration of relativistic electrons, making them observable at radio wavelengths, or contributing to a dormant reservoir of low-energy cosmic rays in cosmic structures. We present a new suite of cosmological simulations, with simple galaxy formation models calibrated to work at a specific spatial resolution, tailored to study all most important processes of injection of relativistic electrons in evolving large-sale structures: accretion and merger shocks, feedback from active galactic nuclei and winds from star forming regions. We also follow the injection of magnetic fields by active galactic nuclei and star formation, and compute the observational signatures of these mechanisms. We find that the injection of cosmic ray electrons by shocks is the most volume filling process, and that it also dominates the energy density of fossil relativistic electrons in halos. The combination of the seeding mechanisms studied in this work, regardless of the uncertainties related to physical or numerical uncertainties, is more than enough to fuel large-scale radio emissions with a large amount of seed fossil electrons. We derive an approximated formula to predict the number of fossil cosmic ray electrons injected by z=0 by the total activity of shocks, AGN and star formation in the volume of halos. By looking at the maximum possible contribution to the magnetisation of the cosmic web by all our simulated sources, we conclude that galaxy formation-related processes, alone, cannot explain the values of Faraday Rotation of background polarised sources recently detected using LOFAR.
format Preprint
id arxiv_https___arxiv_org_abs_2501_19041
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The evolution of cosmic ray electrons in the cosmic web: seeding by AGN, star formation and shocks
Vazza, F.
Gheller, C.
Zanetti, F
Tsizh, M.
Carretti, E.
Mtchedlidze, S.
Brueggen, M.
High Energy Astrophysical Phenomena
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
Several processes in the Universe convert a fraction of gas kinetic energy into the acceleration of relativistic electrons, making them observable at radio wavelengths, or contributing to a dormant reservoir of low-energy cosmic rays in cosmic structures. We present a new suite of cosmological simulations, with simple galaxy formation models calibrated to work at a specific spatial resolution, tailored to study all most important processes of injection of relativistic electrons in evolving large-sale structures: accretion and merger shocks, feedback from active galactic nuclei and winds from star forming regions. We also follow the injection of magnetic fields by active galactic nuclei and star formation, and compute the observational signatures of these mechanisms. We find that the injection of cosmic ray electrons by shocks is the most volume filling process, and that it also dominates the energy density of fossil relativistic electrons in halos. The combination of the seeding mechanisms studied in this work, regardless of the uncertainties related to physical or numerical uncertainties, is more than enough to fuel large-scale radio emissions with a large amount of seed fossil electrons. We derive an approximated formula to predict the number of fossil cosmic ray electrons injected by z=0 by the total activity of shocks, AGN and star formation in the volume of halos. By looking at the maximum possible contribution to the magnetisation of the cosmic web by all our simulated sources, we conclude that galaxy formation-related processes, alone, cannot explain the values of Faraday Rotation of background polarised sources recently detected using LOFAR.
title The evolution of cosmic ray electrons in the cosmic web: seeding by AGN, star formation and shocks
topic High Energy Astrophysical Phenomena
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2501.19041