科研之友
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摘要
We analyze the Chandra High Energy Transmission Grating Spectrometer observation of the Seyfert 2 AGN IRAS 18325-5926. We detect a upsilon = -360(-66)(+41) km s(-1) blueshifted ionized absorber in the X-ray spectrum, with photoionization parameter log xi = 2.0(-0.1)(+0.1) and hydrogen column density N-H = 1.55(-0.38)(+0.75) x10(21) cm(-2). The absorber may be a photoionized wind originating in the obscuring torus/global covering around the black hole or outer edge of the accretion disk. The estimated mass outflow rate suggests that the supermassive black hole in IRAS 18325-5926 may significantly affect the large-scale environment of the host galaxy, unless the solid angle subtended by the outflow or the gas filling factor is small. A second warm absorber may be needed to explain the absorption features in the vicinity of the iron K edge, although insufficient counts in the data beyond 7.0 keV make it difficult to assess the nature of the second absorber. Most plausible is a high ionization (log xi similar to 2.3 to 2.6), high column density (N-H similar to 10(23) cm(-2)) absorber with upsilon similar to -3000 to 0 km s(-1), although these parameters are not well constrained. We also examine the broad Fe K emission line in the spectrum, which is likely due to Fe xxv in a highly ionized accretion disk inclined at 25 degrees, consistent with the XMM-Newton EPIC observations of the emission line. Because we are able to view both the obscuring gas and the accretion disk of IRAS 18325-5926, the surrounding gas of IRAS 18325-5926 may be patchy or we are viewing the system at an angle just grazing the obscuring torus.
- 出版日期2011-3-1
