Skip to main content
Article thumbnail
Location of Repository

The Gunn-Peterson effect and the Lyman alpha forest

By Sergei A. Levshakov and Wilhelm H. Kegel


We show that spatial correlations in a stochastic large scale velocity field in an otherwise smooth intergalactic medium (homogeneous comoving density) superposed on the general Hubble flow, may cause a ‘line-like ’ structure in QSO spectra similar to the population of unsaturated Lyα forest lines which usually are attributed to individual clouds with 1011 < ∼ NHI < ∼ 5 × 1013 cm−2. Therefore there is no clear observational distinction between a diffuse intergalactic medium and discrete intergalactic clouds. It follows that the HI-density in the diffuse intergalactic medium might be substantially underestimated if it is determined from the observed intensity distribution near the apparent continuum in high resolution spectra of QSOs. Our tentative estimate implies a diffuse neutral hydrogen opacity τGP ∼ 0.3 at z ∼ 3 and a current baryon density ΩIGM ≃ 0.08, assuming a Hubble constant H0 = 70 km s −1 Mpc −1

Year: 2008
OAI identifier: oai:CiteSeerX.psu:
Provided by: CiteSeerX
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • (external link)
  • (external link)
  • Suggested articles

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.