A Suzaku Observation of MCG -2-58-22: Constraining the Geometry of the Circumnuclear Material

The Astrophysical Journal (Impact Factor: 6.28). 05/2011; 732(1). DOI: 10.1088/0004-637X/732/1/36
Source: arXiv

ABSTRACT We have analyzed a long-look Suzaku observation of the active galactic nucleus MCG -2-58-22, a type 1.5 Seyfert with very little X-ray absorption in the line of sight and prominent features arising from reflection off circumnuclear material: the Fe line and Compton reflection hump. We place tight constraints on the power-law photon index (Gamma = 1.80 ± 0.02), the Compton reflection strength (R = 0.69 ± 0.05), and the Fe K emission line energy centroid and width (E = 6.40 ± 0.02 keV, v FWHM < 7100 km s-1). We find no significant evidence either for emission from strongly ionized Fe, or for a strong, relativistically broadened Fe line, indicating that perhaps there is no radiatively efficient accretion disk very close in to the central black hole. In addition, we test a new self-consistent physical model from Murphy and Yaqoob, the "MYTORUS" model, consisting of a donut-shaped torus of material surrounding the central illuminating source and producing both the Compton hump and the Fe K line emission. From the application of this model we find that the observed spectrum is consistent with a Compton-thick torus of material (column density N H = 3.6+1.3 - 0.8 × 1024 cm-2) lying outside of the line of sight to the nucleus, leaving it bare of X-ray absorption in excess of the Galactic column. We calculate that this material is sufficient to produce all of the Fe line flux without the need for any flux contribution from additional Compton-thin circumnuclear material.

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