PERIODICITY REVEALED BY STATISTICS OF THE ABSORPTION-LINE REDSHIFTS OF QUASARS

We study the properties of the heavy-element absorption systems and th eir evolution with redshift based on the distribution of the free path s (FPs) of the light rays which come from QSOs and are intercepted by absorbers. We find that the mean free path (MFP) regularly varies with the cosmic time and has a definite periodic component, which shows a marked evolution of the absorbers. For the MFP calculated by the catal og of the absorption-line redshifts of Junkkarinen et al. (1991), an u seful fitting function is <(lambda(0)(t))over bar> approximate to 375 (t(0)/t)[1 + 0.125 cos(2 pi t/tau)](-2) h(-1) Mpc, where period tau = 1.55 10(8) h(-1) yr is a result of power-spectrum analysis, t(0) = 2/( 3H(0)) and t = t(0)(1 + (z) over bar)(-3/2) for q(0) = 0.5. This perio d tau is quite consistent with the dynamic time scale of galaxies, it supports the view that the heavy-element absorption systems are due to intervening protogalaxies. The observational periodicity can be expla ined as an effect of oscillation of the protogalaxy after the gravitat ional collapse. That is to say, the heavy-element absorption systems m ight be due to the protogalaxies which separated from the general expa nsion of the universe at the cosmic time t approximate to tau = 1.55-1 0(8) h(-1) yr, the redshift z approximate to 11, and the protogalaxies might be pulsating with the period tau at the QSO epoch.