Volume 390, Number 1, July IV 2002
|Page(s)||13 - 25|
|Published online||05 July 2002|
High matter density peaks from UVES observations of QSO pairs: Correlation properties and chemical abundances*
Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris, France
2 LERMA, Observatoire de Paris, 61 Av. de l'Observatoire, 75014 Paris, France
3 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
4 Osservatorio Astronomico di Trieste, via G.B. Tiepolo, 11, 34131 Trieste, Italy
Corresponding author: V. D'Odorico, firstname.lastname@example.org
Accepted: 15 May 2002
We study the transverse clustering properties of high matter density peaks as traced by high column density absorption systems (either Lyman limit systems characterized by cm-2 or systems with Å) at redshifts between 2 and 3 with UVES spectra of two QSO pairs (UM680/UM681 at 56 arcsec angular separation and Q2344+1228/Q2343+1232 at 5 arcmin angular separation) and a QSO triplet (Q2139-4433/Q2139-4434/Q2138-4427 at 1, 7 and 8 arcmin angular separation). We find 3 damped Lyman-α systems ( cm-2): 2 coinciding with strong metal systems in the nearby line of sight and 1 matching the emission redshift of the paired QSO; plus 7 Lyman limit systems: 4 forming two matching couples and 3 without a corresponding metal system within ~3000 km s-1in the coupled line of sight. In summary, we detect five out of ten matching systems within 1000 km s-1, indicating a highly significant overdensity of strong absorption systems over separation lengths from ~1 to 8 h-1 Mpc. The observed coincidences could arise in gas due to starburst-driven superwinds associated with a quasar or a galaxy, or gas belonging to large scale structures like filaments or sheets. We also determine chemical abundance ratios for three damped Lyman-α systems. In particular, for the damped system at in the spectrum of Q2344+1228, new estimates of the ratios O/Fe, C/Fe are obtained: , . They indicate that O and C are not over-solar in this system.
Key words: galaxies: abundances / galaxies: high-redshift / quasars: absorption lines / cosmology: observations
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.