Phenomenology of Gamma-Ray Jets

TL;DR

This paper explores the phenomenology of gamma-ray jets, focusing on gamma-ray and neutrino production, variability, and how observations can constrain jet properties like the Doppler factor.

Contribution

It introduces calculations of gamma- and pi-spheres for different photon fields and proposes a model for rapid TeV flares consistent with low Doppler factors.

Findings

Gamma-ray observations can constrain jet Doppler factors.

A new model explains rapid TeV flares with low Doppler factors.

Discussion on prospects for detecting VHE neutrinos from jets.

Abstract

We discuss some phenomenological aspects of $\gamma$-ray emitting jets. In particular, we present calculations of the $\gamma$-sphere and $\pi$-sphere for various target photon fields, and employ them to demonstrate how $\gamma$-ray observations at very high energies can be used to constraint the Doppler factor of the emitting plasma and the production of VHE neutrinos. We also consider the implications of the rapid TeV variability observed in M87 and the TeV blazars, and propose a model for the very rapid TeV flares observed with HESS and MAGIC in some blazars,that accommodates the relatively small Doppler factors inferred from radio observations. Finally, we briefly discuss the prospects for detecting VHE neutrinos from relativistic jets.