{A Detection of an X-ray Wind and an Ionized Disk in the Chandra HETGS Observation of the Seyfert 2 Galaxy IRAS 18325-5926}

Date Published:

mar

Abstract:

{We analyze the Chandra High Energy Transmission Grating Spectrometer observation of the Seyfert 2 AGN IRAS 18325-5926. We detect a v = -360$^{+41}$ $_{-66}$ 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$^{+0.75}$ $_{-0.38}$ {\times} 10$^{21}$ 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 {$\xi$} \~{} 2.3 to 2.6), high column density (N $_{H}$ \~{} 10$^{23}$ cm$^{-2}$) absorber with v \~{} -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{\deg}, 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. }

Notes:

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