Suzaku Observation of IRAS 00521-7054, a Peculiar Type-II AGN with a Very Broad Feature at 6 keV

Abstract

IRAS 00521-7054 is the first Seyfert 2 in which the presence of an extremely large Fe Kα line has been claimed. We report here on the analysis of a 100 ks Suzaku observation of the source. We confirm the existence of a very strong excess over the power-law X-ray continuum at E ~ 6 keV (EW ~= 800 eV), extending down to ~4.5 keV, and found that the X-ray spectrum of the source can be explained by two different models. (1) An absorption scenario in which the X-ray source is obscured by two fully covering ionized absorbers with a strong reflection component from neutral material (R ~ 1.7), a blackbody component, and four narrow Gaussian lines (corresponding to Fe Kα, Fe Kβ, Fe XXV, and Fe XXVI). (2) A reflection scenario in which the X-ray spectrum is dominated by an obscured (log N _H ~ 22.9), blurred reflection produced in an ionized disk around a rotating supermassive black hole with a spin of a >= 0.73 and affected by light-bending (R ~ 2.7), plus two narrow Gaussian lines (corresponding to Fe Kα and Fe Kβ). The narrow Fe Kα and Kβ lines are consistent with being produced by ionized iron and in particular by Fe XIV-Fe XVI and Fe XII-Fe XVI for the absorption and reflection scenario, respectively. While the X-ray continuum varies significantly during the observation, the intensity of the broad feature appears to be constant, in agreement with both the absorption and reflection scenarios. For both scenarios we obtained a steep power-law emission (Γ ~ 2.2-2.3), and we speculate that the source might be an obscured narrow-line Seyfert 1.