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Astron. Astrophys. 329, 821-826 (1998)

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Periodicity revealed by statistics of the absorption-line redshifts of quasars

Yong-zhen Liu 1, Fu-xing and Hu 2

1 Department of Physics, Graduate School, University of Science and Technology of China, P.O. Box 3908, Beijing, P.R. China
2 Purple Mountain Observatory, Academia Sinica, Nanjing 210008, P.R. China

Received 17 February 1997 / Accepted 29 August 1997


We study the properties of the heavy-element absorption systems and their evolution with redshift based on the distribution of the free paths (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 catalog of the absorption-line redshifts of Junkkarinen et al. (1991), an useful fitting function is


where period [FORMULA] is a result of power-spectrum analysis, [FORMULA] and [FORMULA] for [FORMULA]. This period [FORMULA] 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 explained as an effect of oscillation of the protogalaxy after the gravitational collapse. That is to say, the heavy-element absorption systems might be due to the protogalaxies which separated from the general expansion of the universe at the cosmic time [FORMULA], the redshift [FORMULA], and the protogalaxies might be pulsating with the period [FORMULA] at the QSO epoch.

Key words: quasars: absorption lines – galaxies: redshift – cosmology: observations; large scale structure of universe

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© European Southern Observatory (ESO) 1998

Online publication: December 16, 1997