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 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 ξ = 2.0+0.1 -0.1 and hydrogen column density N H = 1.55+0.75 -0.38 × 1021 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 ξ ~ 2.3 to 2.6), high column density (N H ~ 1023 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°, 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2011
- DOI:
- 10.1088/0004-637X/729/1/30
- arXiv:
- arXiv:1101.1344
- Bibcode:
- 2011ApJ...729...30M
- Keywords:
-
- galaxies: active;
- galaxies: individual: IRAS 18325-5925;
- galaxies: Seyfert;
- X-rays: galaxies;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 28 pg, 5 tables, 6 figures