# Enhancing the Spectral Hardening of Cosmic TeV Photons by Mixing with Axionlike Particles in the Magnetized Cosmic Web

## TL;DR

This paper investigates how mixing cosmic TeV photons with axionlike particles in the magnetized cosmic web can cause spectral hardening, potentially detectable by future telescopes, revealing insights into cosmic magnetic fields.

## Contribution

It introduces a new model of extragalactic magnetic fields from cosmological simulations, showing enhanced photon-ALP conversions in cosmic filaments and their observational implications.

## Key findings

- Photon-ALP conversions cause spectral hardening of TeV photons.
- Enhanced effects in cosmic filaments due to simulated magnetic fields.
- Potential detection with upcoming Cherenkov Telescope Array.

## Abstract

Large-scale extragalactic magnetic fields may induce conversions between very-high-energy photons and axionlike particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. However, in simplified "cell" models, used so far to represent extragalactic magnetic fields, this mechanism would be strongly suppressed by current astrophysical bounds. Here we consider a recent model of extragalactic magnetic fields obtained from large-scale cosmological simulations. Such simulated magnetic fields would have large enhancement in the filaments of matter. As a result, photon-ALP conversions would produce a significant spectral hardening for cosmic TeV photons. This effect would be probed with the upcoming Cherenkov Telescope Array detector. This possible detection would give a unique chance to perform a tomography of the magnetized cosmic web with ALPs.