Abstract. We present a new catalog of absorption-line systems identified in the quasar spectra. It contains data on 821 QSOs and 8558 absorption systems comprising 16 139 absorption lines with measured redshifts in the QSO spectra. The catalog includes absorption-line systems consisting of lines of heavy elements, lines of neutral hydrogen, Lyman limit systems, damped Lyα absorption systems, and broad absorption-line systems. Using the data of the present catalog we also discuss redshift distributions of absorption-line systems.

The spatial-temporal distribution of absorptionline systems (ALSs) observed in QSO spectra within the cosmological redshift interval z = 0.0-4.3 is investigated on the base of our updated catalog of absorption systems. We consider so-called metallic systems including basically lines of heavy elements. The sample of the data displays regular variations (with amplitudes ∼15-20%) in the z-distribution of ALSs as well as in the η-distribution, where η is a dimensionless line-of-sight comoving distance, relatively to smoother dependences. The η-distribution reveals the periodicity with period η = 0.036 ± 0.002, which corresponds to a spatial characteristic scale (108 ± 6)h −1 Mpc or (alternatively) a temporal interval (350 ± 20)h −1 Myr for the CDM cosmological model. We discuss the possibility of a spatial interpretation of the results, treating the pattern obtained as a trace of an order imprinted on the galaxy clustering in the early Universe.

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A statistical analysis of the space-time distribution of absorption-line systems (ALSs) observed in QSO spectra within the cosmological redshift interval $z$=0.0--3.7 is carried out on the base of our catalog of absorption systems (Ryabinkov et al. 2003). We confirm our previous conclusion that the $z$-distribution of absorbing matter contains non-uniform component displaying a pattern of statistically significant alternating maxima (peaks) and minima (dips). Using the wavelet transformation we determine the positions of the maxima and minima and estimate their statistical significance. The positions of the maxima and minima of the $z$-distributions obtained for different celestial hemispheres turn out to be weakly sensitive to orientations of the hemispheres. The data reveal a regularity (quasi-periodicity) of the sequence of the peaks and dips with respect to some rescaling functions of $z$. The same periodicity was found for the one-dimensional correlation function calculated for the sample of the ALSs under investigation. We assume the existence of a regular structure in the distribution of absorption matter, which is not only spatial but also temporal in nature with characteristic time varying within the interval 150--650 Myr for the cosmological model applied.Comment: 28 pages, 10 figures, accepted by MNRA