Iron line reverberation mapping in Ghasemi-Nodehi-Bambi background

TL;DR

This paper explores how iron line reverberation mapping can be used to test the spacetime geometry around black holes, specifically within the Ghasemi-Nodehi-Bambi metric, to constrain deviations from Kerr black holes.

Contribution

It provides a reverberation mapping analysis of the Ghasemi-Nodehi-Bambi black hole metric to constrain spacetime parameters, extending previous parametrizations.

Findings

Most parameters can be constrained through reverberation mapping.

Parameter b11 remains unconstrained.

Parameter b4 is difficult to constrain.

Abstract

The reverberation associated with the iron line is the time lag between direct photons from the corona and the photons reflected from the disk. The resulting line spectrum is called the 2D transfer function. The shape of the 2D transfer function is determined by the geometry of spacetime and the properties of BH. In a paper (Ghasemi-Nodehi and Bambi in EPJC 76:290, 2016), the authors have proposed a parametrization. This parametrization is aimed to test the Kerr nature of astrophysical black hole candidates. In this paper, I provide a reverberation mapping of the Ghasemi-Nodehi-Bambi metric in order to constrain the parameter of spacetime. All parameters can be constrained with the exception of b11. The parameter b4 is harder to constrain too.