We have obtained high, 11 and 14 km s^-1^, and medium, 40 and 53 km s^-1^, resolution spectra of the z_em_ = 4.11 quasar Q 0000-2619 covering the range 4400 A to 9265 A. We identify nine metal absorption systems, of which four were previously known. A fifth previously suggested system at z_abs_ ~ 3.409 (Turushek et al. 1991) is ruled out by our data. Two of the eight systems for which the Lyα line is in the observable range have a damped Lyα line. Six of the nine systems show evidence for complex sub-component structure. At our resolution and S/N we identify a total of 21 subcomponents in the nine systems. Five of the nine systems (11 of the 21 components) fall within the +/-5000 km s^- 1^ range of the emission redshift, and are hence classified as z_abs_ ~ z_em_ absorbers. Data for all lines redward of Lyα emission, plus lines in the Lyman forest belonging to one of the nine metal systems are given. By modelling the absorption lines with Voigt profiles, we have derived estimates for the column densities and the b values of the intervening clouds. Available photoionization models have then been used to derive the degree of ionization and the metal abundances. For the two damped systems we find metal abundances of <= 1% and <= 8% of solar values at redshifts of 3.0541 and 3.3901 respectively. These upper limits are consistent with what would be expected from previous determinations at lower redshifts, and our data are hence compatible with earlier conclusions that no evidence is yet found for chemical evolution of intervening damped and Lyman limit absorbers. For the z_abs_ ~ z_em_ systems we found indications of metallicities comparable to and even in excess of solar values. These much higher values compared to the damped systems, are in favour of the intrinsic hypothesis for these systems.
The metal systems in Q 0000-2619 at high resolution
Savaglio, Sandra
Membro del Collaboration Group
;
1994-01-01
Abstract
We have obtained high, 11 and 14 km s^-1^, and medium, 40 and 53 km s^-1^, resolution spectra of the z_em_ = 4.11 quasar Q 0000-2619 covering the range 4400 A to 9265 A. We identify nine metal absorption systems, of which four were previously known. A fifth previously suggested system at z_abs_ ~ 3.409 (Turushek et al. 1991) is ruled out by our data. Two of the eight systems for which the Lyα line is in the observable range have a damped Lyα line. Six of the nine systems show evidence for complex sub-component structure. At our resolution and S/N we identify a total of 21 subcomponents in the nine systems. Five of the nine systems (11 of the 21 components) fall within the +/-5000 km s^- 1^ range of the emission redshift, and are hence classified as z_abs_ ~ z_em_ absorbers. Data for all lines redward of Lyα emission, plus lines in the Lyman forest belonging to one of the nine metal systems are given. By modelling the absorption lines with Voigt profiles, we have derived estimates for the column densities and the b values of the intervening clouds. Available photoionization models have then been used to derive the degree of ionization and the metal abundances. For the two damped systems we find metal abundances of <= 1% and <= 8% of solar values at redshifts of 3.0541 and 3.3901 respectively. These upper limits are consistent with what would be expected from previous determinations at lower redshifts, and our data are hence compatible with earlier conclusions that no evidence is yet found for chemical evolution of intervening damped and Lyman limit absorbers. For the z_abs_ ~ z_em_ systems we found indications of metallicities comparable to and even in excess of solar values. These much higher values compared to the damped systems, are in favour of the intrinsic hypothesis for these systems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
