Extra-galactic jets: a hard X-ray view

TL;DR

This paper reviews the properties of extragalactic jets, especially blazars, highlighting their emission in hard X-rays, their connection to jet power and accretion, and their potential as sources of neutrinos and cosmic rays.

Contribution

It provides a comprehensive overview of the hard X-ray characteristics of extragalactic jets and discusses their implications for jet power, particle acceleration, and multi-messenger astrophysics.

Findings

Most powerful blazar emission is in hard X-rays or soft gamma-rays.

Jet power often exceeds accretion luminosity, especially in neutrino-producing jets.

Hard X-ray observations reveal jets visible at high redshifts.

Abstract

Extragalactic jets are the most powerful persistent sources of the universe. Those pointing at us are called blazars. Their relativistically boosted emission extends from radio frequencies to TeV energies. They are also suspected to be the sources of energetic neutrinos and high energies cosmic rays. The study of their overall spectrum indicates that most of the emission of powerful blazars is in hard X-rays or in soft gamma-rays. In this band we can find the most powerful jets, visible also at high redshifts. It is found that the jet power is linked to the accretion luminosity, and exceeds it, especially if they produce energetic neutrinos, that require the presence of ultrarelativistic protons.