Chandra Detection of OVIII Lyman-alpha Absorption from the Intergalactic Medium
Abstract
We report the first detection of an O 8 Lyα absorption line associated with a possible intervening, spiral-rich galaxy group along the sightline towards PKS 2155-304 with the Chandra LETG-ACIS. We constraint the intragroup gas that gives rise to this absorption line to a baryon density in the range 1.7 x 10-5 < nb < 2x 10-4 cm-3 and a temperature of 4-5*E6 K. The estimated physical states of absorption material are in accordance with those of the warm/hot intergalactic medium (WHIM) that is predicted from hydrodynamic simulations. Extroplating from this single detection implies a large fraction of the ``missing baryons'' ( ~ 70% of the WHIM) are probed by the O 8 absorber.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AAS...19916103F