Chandra Detection of Local Warm-Hot Gas toward Markarian 279
Abstract
We report the Chandra detection of O VII Kα absorption at z=0 in the direction of the z=0.03 Seyfert 1 galaxy Mrk 279. The high-velocity cloud Complex C lies along this line of sight, with H I 21 cm emission and O VI λ1032 absorption both observed at velocities of roughly-150 km s-1 relative to the local standard of rest. We present an improved method for placing limits on the Doppler parameter and column density of a medium when only one unresolved line can be measured; this method is applied to the O VII absorption seen here, indicating that the O VII Doppler parameter is inconsistent with that of any low-velocity (Galactic thick disk) or high-velocity O VI [(O VI)HV] component. Direct association of the O VII with the (O VI)HV is further ruled out by the high temperatures required to produce the observed (O VI)HV/O VII ratio and the significant velocity difference between the O VII and (O VI)HV lines. If the O VII absorption is associated with a very broad, undetected O VI component, then the absorption must be broadened by primarily nonthermal processes. The large velocity dispersion and possible slight redshift of the O VII absorption (as well as limits on the absorber's temperature and density) may be indicative of a local intergalactic medium origin, although absorption from a hot, low-density Galactic corona cannot be ruled out.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2006
- DOI:
- 10.1086/504071
- arXiv:
- arXiv:astro-ph/0512003
- Bibcode:
- 2006ApJ...645..179W
- Keywords:
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- Cosmology: Observations;
- Galaxies: Intergalactic Medium;
- X-Rays: Galaxies: Clusters;
- Astrophysics
- E-Print:
- 20 pages including 5 figures, 1 table