Year: 2006
Type: article
Abstract: A significant fraction (40%-50%) of baryons at the present epoch are predicted to be shock-heated to the warm-hot intergalactic medium (WHIM) by our previous numerical simulations. Here we recompute the evolution of the WHIM with several major improvements: (1) galactic superwind feedback processes from galaxy and star formation are explicitly included; (2) major metal species (O V to O IX) are computed explicitly in a nonequilibrium way; and (3) mass and spatial dynamic ranges are larger by factors of 8 and 2, respectively, than in our previous simulations. We find the following: (1) Nonequilibrium calculations produce significantly different results than do ionization equilibrium calculations. (2) The abundance of O VI absorption lines based on nonequilibrium simulations with galactic superwinds is in remarkably good agreement with the latest observations, strongly validating our model, while the predicted abundances for O VII and O VIII absorption lines appear to be lower than the still very uncertain observations. The expected abundances for O VI (as well as Lyα), O VII, and O VIII absorption systems are in the range 50-100 per unit redshift at equivalent width EW = 1 km s -1 , decreasing to 10-20 per unit redshift at EW = 10 km s -1 , to one to three lines for O VII and O VIII and negligible for O VI at EW > 100 km s -1 . (3) Emission lines, primarily O VI and Lyα in the UV and O VII and O VIII in soft X-rays, are potentially observable by future missions, and different lines provide complementary probes of the WHIM in the temperature-density-metallicity phase space. The number of emission lines per unit redshift that may be detectable by planned UV and soft X-ray missions are of order 0.1-1.
Source: The Astrophysical Journal
DOI: 10.1086/506506
Authors: Renyue Cen, Taotao Fang
Institutions: Princeton University, University of California, Berkeley
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2952357522