Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-06-16
Astronomy and Astrophysics
Astrophysics
14 pages with 2 figures. ApJ Letters, in press
Scientific paper
We report the first detection of an OVIII Ly-alpha absorption line associated with an overdense region in the intergalactic medium (IGM) along the sightline towards PKS 2155-304 with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). The absorption line is detected at 4.5 sigma level with cz~16,600 km/s. At the same velocity Shull et al.(1998) detected a small group of spiral galaxies (with an overdensity of delta_gal ~ 100) and low metallicity HI Ly-alpha clouds. We constrain the intragroup gas that gives rise to the OVIII Ly-alpha line to a baryon density in the range 1e-5 < n_b < 7.5e-5 cm^-3 (50 < delta_b < 350) and a temperature of (4-5) x 10^6 K, assuming 0.1 solar abundance. These estimates are in accordance with those of the warm/hot intergalactic medium (WHIM) that are predicted from hydrodynamic simulations. Extrapolating from this single detection implies a large fraction of the ``missing baryons'' (~ 10%, or ~ 30-40% of the WHIM) are probed by the OVIII absorber.
Canizares Calude R.
Davis David S.
Fang Taotao
Lee Jae-Chul
Marshall Herman L.
No associations
LandOfFree
Chandra Detection of OVIII Ly-alpha Absorption from an Overdense Region in the Intergalactic Medium does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Chandra Detection of OVIII Ly-alpha Absorption from an Overdense Region in the Intergalactic Medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chandra Detection of OVIII Ly-alpha Absorption from an Overdense Region in the Intergalactic Medium will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-720259