Suzaku observation of the Phoenix galaxy
Bianchi, S.; Guainazzi, M.; Comastri, A.; Iwasawa, K.; Matt, G.; Nicastro, F.; Awaki, H.; Jimenez-Bailon, E.
Italy, Japan, Spain, Mexico
Abstract
Context: 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.
Aims: 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.
Methods: The {Suzaku} spectrum was analyzed, and the results compared with previous ASCA and XMM-Newton observations.
Results: 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.