X-ray reflected spectra from accretion disk models. I. Constant density atmospheres

TL;DR

This paper develops detailed models of X-ray reflection spectra from accretion disks, accounting for atomic processes, ionization, and Comptonization, to better understand the reprocessed emission in these astrophysical systems.

Contribution

It introduces comprehensive models for illuminated accretion disks with updated atomic data, including effects of incident X-rays, ionization, and Comptonization, advancing previous spectral modeling efforts.

Findings

Identification of the impact of incident X-ray strength on spectra

Quantification of fluorescent Kα line emission and absorption

Demonstration of the significance of Comptonization effects

Abstract

We present new models for illuminated accretion disks, their structure and reprocessed emission. We consider the effects of incident X-rays on the surface of an accretion disk by solving simultaneously the equations of radiative transfer, energy balance and ionization equilibrium over a large range of column densities. We assume plane-parallel geometry and azimuthal symmetry, such that each calculation corresponds to a ring at a given distance from the central object. Our models include recent and complete atomic data for K-shell processes of the iron and oxygen isonuclear sequences. We examine the effect on the spectrum of fluorescent K$\alpha$ line emission and absorption in the emitted spectrum. We also explore the dependence of the spectrum on the strength of the incident X-rays and other input parameters, and discuss the importance of Comptonization on the emitted spectrum.