The physics of non-thermal radiation in microquasars

TL;DR

This paper reviews the physical processes and conditions responsible for non-thermal radiation across the electromagnetic spectrum in microquasars, emphasizing particle acceleration, radiative mechanisms, and absorption effects.

Contribution

It provides a comprehensive overview of the physical elements and processes involved in non-thermal emission in microquasars, integrating recent theoretical insights.

Findings

Identification of key radiative mechanisms from radio to gamma-rays.

Analysis of particle acceleration and transport in microquasar jets.

Assessment of photon absorption effects on observed emission.

Abstract

Microquasars are binary systems that harbor a normal star and a compact object (black-hole or neutron star), and show relativistic outflows (or jets). The matter that forms these jets is of likely stellar origin, previously expelled from the star and trapped in the potential well of the compact object. This matter is accreted by the compact object, forming a disk due to its angular momentum, and is eventually ejected in the form of a bipolar outflow (the jets), which generates radio emission and could also be a very high-energy emitter. To study and understand the radiation from microquasars, there is a set of elements that can play a major role and are to be taken into account: the photons and the expelled matter from the star in the case of high-mass systems; the accreted matter radiation; the jet; the magnetic field carried by the jet or filling the binary system; and the medium surrounding the microquasar at large scales (~pc). In this lecture, we consider these elements of the microquasar scenario and briefly describe the physical conditions and processes involved in the production of non-thermal radiation from radio to gamma-rays. The required energetics, particle acceleration and transport, several radiative mechanisms, and the impact of different photon absorption processes, are discussed.