Intergalactic electromagnetic cascades in the magnetized Universe as a tool of astroparticle physics

TL;DR

This paper reviews the physics of intergalactic electromagnetic cascades influenced by extragalactic magnetic fields, discussing different regimes, constraints, and observational sensitivities relevant to astroparticle physics.

Contribution

It provides a comprehensive overview of cascade regimes, current constraints on the extragalactic magnetic field, and the potential of gamma-ray instruments to probe these fields.

Findings

Different cascade regimes depend on magnetic field and electron energy parameters.

Current observational constraints limit the strength and structure of the EGMF.

Gamma-ray instruments have varying sensitivities to EGMF parameters.

Abstract

We review the physics of intergalactic electromagnetic cascades in the presence of the extragalactic magnetic field (EGMF). Various regimes of intergalactic electromagnetic cascades are considered depending on the number of cascade generations, the value of the cascade electron deflection angle, and the relations between the EGMF coherence length, typical cascade $\gamma$-ray mean free path, and electron energy loss length. We also review contemporary constraints on the EGMF parameters and explore the sensitivity of various $\gamma$-ray instruments to the EGMF parameters.