Effects of inhomogenuity and anisotropy of radiation field on production and absorption of high energy radiation

TL;DR

This paper examines how the geometry and distribution of electrons and radiation fields influence gamma-ray production and absorption in astrophysical sources, providing simplified scaling factors for different configurations.

Contribution

It introduces analytical scaling factors for gamma-ray emission and absorption considering various geometries and electron distributions in emission regions.

Findings

A 3D Gaussian electron distribution yields 0.222 times lower flux than homogeneous models.

Full absorption calculations can be approximated by simpler models when absorption is less than an order of magnitude.

Absorption is significantly weaker in Gaussian electron distributions compared to homogeneous spheres.

Abstract

We investigate the geometrical effects affecting the production and absorption of gamma-ray radiation emitted in inverse Compton scattering in the synchrotron-self-Compton process. We evaluate the effect of the anisotropy of the radiation field seen by the scattering electrons homogeneously distributed in the emission region. Next, we also consider inhomogeneous distribution of electrons and investigate the effect of it in the spherically symmetric emission region. We also study a cylindrical shape of the emission region and its effect on the isotropy of the emitted radiation. We obtain simple numerical factors that scale the emission for different assumptions about the geometry of the emission region and the distribution of the emitting electrons. For a 3D Gaussian spatial distribution of the electrons we obtain 0.222 times lower flux than for homogeneous emission region. Finally, we also evaluate the absorption of the radiation produced in the different scenarios, and compare the full calculations with the two most commonly assumed simplifications. We find that for cases when the absorption is lesser than by one order of magnitude, the full calculations for homogeneous sphere can be well approximated with homogeneously-emitting slab, while the absorption in the case of 3D Gaussian distribution of electrons is significantly weaker.