Simulating acceleration and radiation processes in X-ray binaries

TL;DR

This paper introduces a new computational code to simulate the microphysics of relativistic plasmas in X-ray binaries, aiming to understand their spectral states through various acceleration mechanisms.

Contribution

The paper presents a novel one-zone code that models coupled particle-photon kinetics, including multiple microphysical processes relevant to high-energy plasmas in X-ray binaries.

Findings

The code can simulate thermal and non-thermal plasma states.

Preliminary results show different acceleration processes can reproduce spectral states.

The model includes mechanisms like synchrotron self-absorption and Coulomb collisions.

Abstract

The high energy emission of microquasars is thought to originate from high energy particles. Depending on the spectral state, the distribution of these particles can be thermal with a high temperature (typically 100 keV) or non-thermal and extending to even higher energy. The properties of high energy plasmas are governed by a rich microphysics involving particle-particle collisions and particles-photons interactions. We present a new code developed to address the evolution of relativistic plasmas. This one-zone code focuses on the microphysics and solves the coupled kinetic equations for particles and photons, including Compton scattering, synchrotron emission and absorption, pair production and annihilation, bremsstrahlung emission and absorption, Coulomb interactions, and prescriptions for additional particle acceleration and heating. It can in particular describe mechanisms such a thermalisation by synchrotron self-absorption and Coulomb collisions. Using the code, we investigate whether various acceleration processes, namely thermal heating, non-thermal acceleration and stochastic acceleration, can reproduce the different spectral states of microquasars. Premilinary results are presented.