HI 21cm absorption beyond the epoch of re-ionization

Details HI 21cm absorption beyond the epoch of re-ionization HI 21cm absorption beyond the epoch of re-ionization

2002-05-13

arxiv.org/abs/astro-ph/0205169v2

Astrophys.J. 577 (2002) 22-30

Astronomy and Astrophysics

Astrophysics

aas2pp4. to appear in the Astrophysical Journal. rev1: added paragraph

Scientific paper

10.1086/342179

We explore the possibility of detecting HI 21cm absorption by the neutral intergalactic medium (IGM) toward very high redshift radio sources. The epoch considered is between the time when the first ionizing sources form and when the bulk of the neutral IGM becomes ionized. Due to the extreme Ly-alpha opacities of the neutral IGM, objects within this 'gray age' can only be observed at wavelengths longer than about 1micron. We use the latest simulations of the evolution of the IGM in the context of LambdaCDM structure formation models constrained by observations of the highest redshift QSOs to predict the optical depth as a function of frequency of the neutral IGM due to the HI 21cm line. We then simulate radio spectra assuming observational parameters for future large area radio telescopes. These spectra show that HI 21cm absorption studies could be a powerful probe of the rich structure of the neutral IGM prior to the epoch of reionization, including 1% absorption by the mean neutral IGM, plus deeper, narrow lines (5% and a few km/s). Most of the variations in transmissivity are due to the mild density inhomogeneities with typical values of the cosmic overdensity of about 10, precisely the structures that at later times give rise to the Ly-alpha forest. We also consider sensitivity limits and the evolution of radio source populations, and conclude that it is reasonable to hypothesize the existence of an adequate number of high-z radio sources against which such absorption studies could be performed.

Affiliated with

Also associated with

No associations

Rating

HI 21cm absorption beyond the epoch of re-ionization 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 HI 21cm absorption beyond the epoch of re-ionization, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and HI 21cm absorption beyond the epoch of re-ionization will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-422210