An alternative model for the Ly-alpha absorption forest.

The absorption spectrum on the blue side of the Lyα emission line of high redshift quasars is generally proposed to be caused by the absorption of neutral hydrogen in isolated intergalactic clouds - the Lyα clouds, which have the primordial composition. Following some early suggestions, a simulation in this paper shows that a diffusely distributed baryonic intergalactic medium (IGM) left over from the primordial nucleosynthesis can also produce these forest-like absorption features on a quasar spectrum at the Lyα transition frequency. The observed Lyα forest spectra would thus be either seriously contaminated by the contribution from the diffuse medium or totally due to it