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Session 51 - Galaxy Evolution and the Intergalactic Medium.
Display session, Wednesday, June 10
Atlas Ballroom,

[51.10] Spectroscopy of QSO Triplets: Probing the Shape of Lyman Alpha Forest Absorbers

A. P. S. Crotts (Columbia University)

We present data from three groups of three QSOs apiece with the aim of using the absorption-line spectroscopy of intervening gas to determine the size, clustering and particularly the shape of the objects which give rise to the Lyman \alpha forest. These three triplets span comoving separations of 0.5 to 5 Mpc (for H_0 = 100 km s^-1 Mpc^-1), primarily at the lower end of this range, which are a good match to the size of objects with low H I column densities found in recent numerical simulations of the hydrodynamic and gravitational evolution at redshifts of \sim2-3. We present expanded results from the statistical techniques outlined in Crotts amp; Fang (1998) using triplets to measure the projected shape, velocity structure and absorber linestrength homogeneity as indications of the morphology of the absorbers. We also combine these results with other absorption-line data from QSO sightline pairs to study the clustering and size of absorbers and to sense large scale structure in the H I distribution. We also discuss how these constraints affect estimates of the (highly significant) contribution of Lyman \alpha forest absorbers to the total baryonic content of the Universe.

Program listing for Wednesday