A Galactic Origin for the Local Ionized X-ray Absorbers
Name
Canizares-A Galactic Origin.pdf
Size
146.89 KB
Format
Adobe PDF
Checksum (MD5)
9f478bce4596f7f3299d355aeb8de8d7
Author(s)
Fang, Taotao
Mckee, Christopher F.
Canizares, Claude R.
Wolfire, Mark
Date Issued
June 2006
Journal
Astrophysical Journal
Publisher
IOP Publishing
Citation
Fang, Taotao et al. “A Galactic Origin for the Local Ionized X‐Ray Absorbers.” The Astrophysical Journal 644.1 (2006): 174-179.
Version
Author's final manuscript
Abstract
Recent Chandra and XMM-Newton observations of distant quasars have shown strong local (z ~ 0) X-ray absorption lines from highly ionized gas, primarily He-like oxygen. The nature of these X-ray absorbers, i.e., whether they are part of the hot gas associated with the Milky Way or part of the intragroup medium in the Local Group, remains a puzzle due to the uncertainties in the distance. We present in this paper a survey of 20 AGNs with Chandra and XMM-Newton archival data. About 40% of the targets show local O VII He α absorption with column densities around 10[superscript 16] cm[superscript -2]; in particular, O VII absorption is present in all the high-quality spectra. We estimate that the sky covering fraction of this O VII-absorbing gas is at least 63%, at 90% confidence, and likely to be unity given enough high-quality spectra. On the basis of (1) the expected number of absorbers along sight lines toward distant AGNs, (2) joint analysis with X-ray emission measurements, and (3) mass estimation, we argue that the observed X-ray absorbers are part of the hot gas associated with our Galaxy. Future observations will significantly improve our understanding of the covering fraction and provide robust tests of this result.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1086/500310
