The Variable X-ray Spectrum of Markarian 766 - II. Time-Resolved Spectroscopy

TL;DR

This study uses time-resolved spectroscopy to analyze the spectral variability of the AGN Mrk 766, concluding that a complex, multi-layered absorber, likely a disk wind, primarily drives the observed spectral changes.

Contribution

It demonstrates that rapid opacity changes in a multi-layered absorber dominate spectral variability, clarifying the roles of scattering and absorption effects in AGN spectra.

Findings

Absorber variations, especially in a disk wind, are the main cause of spectral changes.

Rapid changes in scattering and direct emission also contribute to variability.

Spectral variability can be explained by either scattering or absorption effects, with absorption being dominant.

Abstract

CONTEXT: The variable X-ray spectra of AGN systematically show steep power-law high states and hard-spectrum low states. The hard low state has previously been found to be a component with only weak variability. The origin of this component and the relative importance of effects such as absorption and relativistic blurring are currently not clear. AIMS: In a follow-up of previous principal components analysis, we aim to determine the relative importance of scattering and absorption effects on the time-varying X-ray spectrum of the narrow-line Seyfert 1 galaxy Mrk~766. METHODS: Time-resolved spectroscopy, slicing XMM and Suzaku data down to 25 ks elements, is used to investigate whether absorption or scattering components dominate the spectral variations in Mrk 766.Time-resolved spectroscopy confirms that spectral variability in Mrk 766 can be explained by either of two interpretations of principal components analysis. Detailed investigation confirm rapid changes in the relative strengths of scattered and direct emission or rapid changes in absorber covering fraction provide good explanations of most of the spectral variability. However, a strong correlation between the 6.97 keV absorption line and the primary continuum together with rapid opacity changes show that variations in a complex and multi-layered absorber, most likely a disk wind, are the dominant source of spectral variability in Mrk 766