Presentation 1 : Oral
Matter Clustering from the Lyman-alpha forest (PNC)
Rollinde E., Petitjean P., Colombi C.
The fluctuating Gunn-Peterson paradigm for the origin of the
Lyman-alpha forest is tested by measuring the coherence length
of the absorbing structures in real space from the
cross-correlation of absorption spectra of a sample of quasars
in pairs and groups at z~2 observed with FORS2 and UVES
at the UT2 Kuyen ESO telescope. The transverse coherence length is similar
to that measured in velocity space from the line of sight
correlation function. The comparison of transverse to longitudinal
correlation length constrains the cosmological constant
to Omega_{\Lambda}< 0.9. The larger samples of absorption spectra
of QSO pairs with separations of a few arcminutes currently assembled
should tighten this rather weak constraint considerably.