Simultaneous spectral and reverberation modelling of relativistic reflection in Mrk 335

TL;DR

This paper develops a combined spectral and timing model for X-ray observations of Mrk 335, revealing insights into the black hole's environment, including the accretion disc and corona, through simultaneous fitting of spectral and lag data.

Contribution

It introduces a comprehensive model that simultaneously fits spectral and reverberation timing data, constraining black hole and accretion disc parameters in Mrk 335.

Findings

Black hole mass estimated at ~1.3 x 10^7 M_sun

Disc inclination of 45 degrees

Small X-ray source height of about 2 r_g

Abstract

We present an X-ray spectral and timing model to investigate the broad and variable iron line seen in the high flux state of Mrk 335. The model consists of a variable X-ray source positioned along the rotation axis of the black hole that illuminates the accretion disc producing a back-scattered, ionized reflection spectrum. We compute time lags including full dilution effects and perform simultaneous fitting of the 2-10 keV spectrum and the frequency-dependent time lags of 2.5-4 vs. 4-6.5 keV bands. The best-fitting parameters are consistent with a black hole mass of approximately 1.3 x 10^7 M_sun, disc inclination of 45 degrees and the photon index of the direct continuum of 2.4. The iron abundance is 0.5 and the ionization parameter is 10^3 erg cm / s at the innermost part of the disc and decreases further out. The X-ray source height is very small, approximately 2 r_g. Furthermore, we fit the Fe L lags simultaneously with the 0.3-10 keV spectrum. The key parameters are comparable to those previously obtained. We also report the differences below 2 keV using the xillver and reflionx models which could affect the interpretation of the soft excess. While simultaneously fitting spectroscopic and timing data can break the degeneracy between the source height and the black hole mass, we find that the measurements of the source height and the central mass significantly depend on the ionization state of the disc and are possibly model-dependent.