X-ray reflection spectroscopy with improved calculations of the emission angle

TL;DR

This paper introduces an advanced X-ray reflection model that accurately calculates emission angles across black hole accretion disks, addressing previous approximations to better analyze high-quality spectra.

Contribution

The paper presents a new reflection model with improved emission angle calculations, enhancing the accuracy of black hole spectrum analysis.

Findings

More accurate reflection spectra modeling.

Better fit for high-quality X-ray data.

Addresses previous computational limitations.

Abstract

The reflection spectrum produced by a cold medium illuminated by X-ray photons is not isotropic and its shape depends on the emission angle. In the reflection spectrum of an accretion disk of a black hole, the value of the emission angle changes over the disk and, in general, is different from the value of the inclination angle of the disk because of the light bending in the strong gravitational field of the black hole. Current reflection models make some approximations, as calculating a reflection spectrum taking the correct emission angle at every point of the disk into account would be too time-consuming and make the model too slow to analyze observations. In a recent paper, we showed that these approximations are unsuitable to fit high-quality black hole spectra expected from the next generation of X-ray missions. Here, we present a reflection model with improved calculations of the emission angle that solves this problem.