Suzaku observation of the Phoenix Galaxy

TL;DR

This study uses Suzaku observations to analyze the changing X-ray states of the Phoenix Galaxy, revealing variations in absorption and soft excess emission, contributing to understanding the dynamics of changing-look Seyfert 2 galaxies.

Contribution

First detailed Suzaku analysis of the Phoenix Galaxy showing absorption variability and soft excess, enhancing knowledge of changing-look AGN behavior.

Findings

Discovered column density variation over years.

Detected short-term count-rate variability.

Identified soft excess likely from photoionized circumnuclear matter.

Abstract

In recent years, several Seyfert 2 galaxies have been discovered that change state when observed in X-rays a few years apart, switching from Compton-thin to reflection-dominated or viceversa. We observed a member of this class of "Changing-look" sources, the Phoenix Galaxy, with Suzaku, with the aim of better understanding the nature of the variations. The Suzaku spectrum was analyzed, and the results compared with previous ASCA and XMM-Newton observations. The source was caught in a Compton-thin state, as in XMM-Newton, but differently from ASCA. Comparing the Suzaku and XMM-Newton observations, a variation in the column density of the absorber on a time scale of years is discovered. A similar change, but on much shorter time scales (i.e. ks) may also explain the count-rate variations during the Suzaku observations. A soft excess is also present, likely due to continuum and line emission from photoionized circumnuclear matter.