Jet models for black-hole binaries in the hard spectral state

TL;DR

This paper develops a steady-state jet model for black-hole binaries in the hard spectral state, incorporating electron acceleration, magnetic fields, and radiative processes to explain observed spectra.

Contribution

It introduces a comprehensive analytical framework for jet electron distributions considering advection, losses, and various radiative processes in black-hole binary systems.

Findings

Analytic solutions for electron distributions in jets with dominant synchrotron losses.

Model accounts for flat radio spectra via constant dissipation and magnetic flux conservation.

Framework applicable to sources like Cyg X-1 for detailed spectral predictions.

Abstract

This is part one of our study of models of jets with distributed electron acceleration. We present here our assumptions, basic equations, and their solutions for the steady-state electron distribution. We assume the shape of the rate of electron acceleration and the dependencies of its normalization and the magnetic field strength on the height along the jet. Our focus is on the hard spectral state of black-hole binaries, for which we take into account that their typical radio spectra are flat. This appears to require a constant dissipation rate per unit logarithmic length and conservation of the magnetic energy flux. Our electron kinetic equation includes adiabatic and radiative losses and advection, and our photon radiative transfer equation includes synchrotron absorption and emission and Compton emission. Apart from the self-Compton process, we take into account Compton scattering of stellar and accretion photons and absorption of very-high energy gamma-rays by pair production on soft photons. We present a general solution of the kinetic equation with advection and radiative and adiabatic losses and an analytic solution in the case of dominant synchrotron losses in conical jets. In the following paper, we present detailed spectra resulting from our equations as applied to Cyg X-1.