Cosmic Reionization and Galaxy Formation · arXivDesk
astro-ph/0108177Aug 10, 2001A paper in "The Physics of Galaxy Formation", ASP Conf. Ser. 222, Eds. M. Umemura and H. Susa (ASP: San Francisco), pp.109-114
Using 3D radiative transfer calculations on the reionization of an inhomogeneous universe, QSO absorption line systems are simulated and they are compared with observations of Lyα continuum depression at high redshifts. By this comparison, it is found that the metagalactic UV intensity decreases rapidly with z at z>4 as I21=0.5exp[3(4−z)]
Nearby in the stack
, and the reionization must have taken place between
z=6
and 10. Based on this time-dependence of UV background intensity, we explore the collapse of pregalactic clouds in the UV background, and find that the self-shielding is prominent above a mass scale as
MBIF=3.0×1011M⊙[(1+zc)/5]−4.2(I21/0.5)0.6.
This mass scale predicts the bifurcation of galactic morphology, and by confrontation with observations it turns out that the bifurcation mass successfully discriminates between elliptical and spiral galaxies.