Volume 449, Number 1, April I 2006
|Page(s)||33 - 39|
|Section||Cosmology (including clusters of galaxies)|
|Published online||16 March 2006|
Kinematics and star formation activity in the z = 2.03954 damped Lyman- system towards PKS 0458–020
Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014 Paris, France
2 Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, 69120 Heidelberg, Germany e-mail: email@example.com
3 Astrophysik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany
4 LERMA, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
5 European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago, Chile
6 IUCAA, Post Bag 4, Ganesh Khind, Pune 411 007, India
Accepted: 16 November 2005
We present UVES observations of the log N(H i) = 21.7 damped Lyman-α system at zabs = 2.03954 towards the quasar PKS 0458-020. H i Lyman-α emission is detected in the center of the damped Lyman-α absorption trough. Metallicities are derived for Mg ii, Si ii, P ii, Cr ii, Mn ii, Fe ii and Zn ii and are found to be , , , , , , , respectively, relative to solar. The depletion factor is therefore of the order of [Zn/Fe] = 0.65. We observe metal absorption lines to be blueshifted compared to the Lyman-α emission up to a maximum of ~100 and 200 km s-1 for low and high-ionization species respectively. This can be interpreted either as the consequence of rotation in a large (~7 kpc) disk or as the imprint of a galactic wind. The star formation rate (SFR) derived from the Lyman-α emission, 1.6 yr-1, is compared with that estimated from the observed C ii* absorption. No molecular hydrogen is detected in our data, yielding a molecular fraction < -6.52. This absence of H2 can be explained as the consequence of a high ambient UV flux which is one order of magnitude larger than the radiation field in the ISM of our Galaxy and originates in the observed emitting region.
Key words: cosmology: observations / galaxies: abundances / galaxies: quasars: absorption lines / galaxies: quasars: individual: PKS 0458-020 / galaxies: kinematics and dynamics
© ESO, 2006
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.