Suzaku Studies of Wide-Band Spectral Variability of the Bright Type I Seyfert Galaxy Markarian 509

TL;DR

This study used Suzaku observations to analyze the spectral variability of the Seyfert galaxy Markarian 509, revealing a stable soft X-ray component and variable thermal Comptonization over weeks, suggesting a multi-zone corona structure.

Contribution

First detailed Suzaku spectral analysis of Markarian 509 showing stable and variable components, supporting a multi-zone Comptonization model for AGN coronae.

Findings

Stable soft X-ray component over 2.2 days

Thermal Comptonization varies over weeks

Consistent spectral modeling with multi-component fit

Abstract

The Type I Seyfert galaxy Markarian 509 was observed with Suzaku in 2010 November, for a gross time span of 2.2 days. Timing and spectral properties of the 0.5-45 keV X-rays, detected with the XIS and HXD, consistently revealed the presence of a soft spectral component that remained constant while the total X- ray intensity varied by \pm10%. This stable soft component, found in the 0.5-3.0 keV range, was interpreted as a result of thermal Comptonization in a corona with a temperature of ~ 0.5 keV and an optical depth of ~ 18. The time-avearged 0.5-45 keV Suzaku spectrum was reproduced successfully, as a combination of this thermal Comptonization component, a harder power-law of photon index ~ 1.8, moderate reflection, and an iron K-emission line. By analyzing four archival Suzaku datasets of the same object obtained in 2006, the thermal Comptonization component, which was stable during the 2.2 day pointing in 2010, was found to vary on time scales of a few weeks, independently of the power-law component. Implications of these results are discussed in terms of the "multi-zone Comptonization" view, obtained with Suzaku from the black hole binary Cygnus X-1.