THE REDSHIFT PROJECTION .2. CAUSTICS AND THE LYMAN-ALPHA FOREST

In a companion paper, it was shown that redshift caustics are an almost inevitable feature of the hierarchical scenario (McGill - Paper I). Here it is argued that these caustics may be the cause of the many sharp absorption features seen towards high redshift quasars - the Ly α forest. It is shown that most of the observed properties of the absorption lines may be accounted for within this model. This is particularly impressive since there are essentially no free parameters in the model. In addition, the data from the double quasar 2345 + 007A, B (Foltz et al) are analysed. The results indicate that the 'characteristic' absorber size of 2-12 h-1 kpc, quoted by some authors (e.g. Rees), is somewhat small.∗ It is known that the characteristic size is not well constrained by the observations but is likely to lie somewhere in the range 3-250 h-1 kpc. © Royal Astronomical Society.