On the light-bending model of X-ray variability of MCG-6-30-15

TL;DR

This study tests the light bending model for X-ray variability in galaxy MCG-6-30-15 using Suzaku data, finding it can explain some variability features but struggles to fit the spectral data due to complex absorption effects.

Contribution

It applies the light bending model to real observational data and explores the conditions under which it can explain variability features in Seyfert galaxy MCG-6-30-15.

Findings

Radial source movement reproduces variability decrease near 5-8 keV.

Spectral fits are poor due to strong reflection and warm absorber effects.

Model predictions differ from observed spectra, highlighting complexities in the source.

Abstract

We apply the light bending model of X-ray variability to Suzaku data of the Seyfert 1 galaxy MCG-6-30-15. We analyze the energy dependence of the root mean square (rms) variability, and discuss conditions necessary for the model to explain the characteristic decrease of the source variability around 5-8 keV. A model, where the X-ray source moves radially rather than vertically close to the disk surface, can indeed reproduce the reduced variability near the energy of the Fe Kalpha line, although the formal fit quality is poor. The model then predicts the energy spectra, which can be compared to observational data. The spectra are strongly reflection dominated, and do not provide a good fit to Suzaku spectral data of the source. The inconsistency of this result with some previous claims can be traced to our using data in a broader energy band, where effects of warm absorber in the spectrum cannot be neglected.