The absorption spectra of Q1107+487 and Q1442+295
摘要
We present the first moderate resolution (~40-120 km s^-1^) spectroscopic observations of the bright (V <~ 16.7) high-redshift QSOs Q1107+487 (z_em_ = 2.965) and Q1442+295 (z_em_ = 2.669). The relatively high signal-to-noise reached in the spectra along with an extensive wavelength coverage of the Lyα and the Lyβ forest allowed us to obtain, through profile fitting, column densities and Doppler parameters of the Lyman clouds toward these QSOs. Our results support the existence of a break in the single power law model for the column density distribution of Lyman clouds at N_H I_ ~ 10^14^ cm^-2^. `Two heavy-element absorption systems (one per QSO) showing component structure with a total velocity spread of ~270 km s^-1^ were detected from the spectra longward of the QSO Lyα emission line. The absorber at z = 2.439 toward 1442+295, for which CIV λλ1548, 1550, C II λ1334 and O I λ1302 lines are detected, exhibits systematic variations with velocity of the ionization state. The complex velocity structure of the high H I column density absorbers toward these QSOs makes the search for deuterium in these systems a very difficult task.