Query : 1998A&A...330...19M

1998A&A...330...19M - Astronomy and Astrophysics, volume 330, 19-24 (1998/2-1)

On the nature of zabs≃zem damped absorbers in quasar spectra.


Abstract (from CDS):

We present spectroscopic observations of the damped Lyαabsorber at redshift z=1.9342 seen in the spectrum of the quasar Q 0151+048A. The redshift of the absorber is greater than the redshift of the quasar, so the system resembles the zabs≃zem damped absorber at z=2.81 towards the quasar PKS 0528-250. We have previously reported the detection of Lyαemission from the latter absorber, one of only two damped absorbers for which Lyαemission has unambiguously been detected. The resemblance between the PKS 0528-250 and Q 0151+048A systems is made closer by the detection of a weak emission feature in the trough of the Q 0151+048A absorber. This leads us to consider whether these zabs≃zem DLA absorbers are different objects to the intervening DLA absorbers. Two possibilities are examined and rejected. Firstly the Q 0151+048A and PKS 0528-250 zabs≃zem absorbers appear to be unrelated to the intrinsic absorbers (i.e. gas close to the quasar nucleus, ejected by the quasar), as intrinsic absorbers are of higher metallicity, have higher ionisation parameter, and show complex absorption profiles. Secondly these two DLA absorbers cannot be equated with the gaseous disks of the quasar host galaxies, as the absorber redshifts differ significantly from the quasar systemic redshifts. It is likely, then, that intrinsically the zabs≃zem DLA absorbers are the same as the intervening DLA absorbers, so that peculiarities in some of the zabs≃zem absorbers can be ascribed to their different environment i.e. proximity to the quasar, or membership of the same cluster as the quasar. We point out that the proximity effect may play some role, by reducing the Lyα-forest line blanketing of any Lyαemission line from zabs≃zem absorbers.

Abstract Copyright:

Journal keyword(s): galaxies: abundances - intergalactic medium - quasars: absorption lines - quasars: individual: Q 0151+048A (QSO 0151+048A)

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 PHL 1222 QSO 01 53 53.8926173376 +05 02 57.118052184   18.04 17.63     ~ 109 0
2 QSO B0528-2505 QSO 05 30 07.9627395840 -25 03 29.900044512   18.17 17.34 17.7   ~ 409 0
3 QSO B2059-360 QSO 21 02 44.6068720464 -35 53 07.081042308   19.18 18.62     ~ 54 0

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