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

Abstract

We analyze the \textit{Chandra} High Energy Transmission Grating Spectrometer (HETGS) observation of the Seyfert $2$ AGN IRAS\,18325-5926. We detect a $v=-360_{-66}^{+41}$~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 $N_{\mathrm{H}}=1.55_{-0.38}^{+0.75}\times 10^{21}$~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 ($\log \xi \sim 2.3$ to $2.6$), high column density ($N_{\mathrm{H}}\sim 10^{23}$~cm${}^{-2}$) absorber with $v\sim -3000$ 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 $25^{\circ }$, consistent with the \textit{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.

28 pg, 5 tables, 6 figures

References in corpus (1)

• Reflection dominated X-ray spectra of Narrow Line Seyfert 1 Galaxies: Mrk 478 and EXO 1346.2+2645

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• The Iron K Line Profile of IRAS 18325-5926
• Highly ionized disc and transient outflows in the Seyfert galaxy IRAS 18325-5926
• Spectral variability of IRAS 18325-5926 and constraints on the geometry of the scattering medium