159 articles – 2000 Notices  [english version]
 HAL : hal-00708878, version 1
 arXiv : 1002.4626
 Monthly Notices of the Royal Astronomical Society 408 (2010) 2128-2136
 Galaxy Counterparts of metal-rich Damped Lyman-alpha Absorbers - I: The case of the z=2.35 DLA towards Q2222-0946
 (2010)
 We have initiated a survey using the newly commissioned X-shooter spectrograph to target candidate relatively metal-rich damped Lyman-alpha absorbers (DLAs). The spectral coverage of X-shooter allows us to search for not only Lyman-alpha emission, but also rest-frame optical emission lines. We have chosen DLAs where the strongest rest-frame optical lines ([OII], [OIII], Hbeta and Halpha) fall in the NIR atmospheric transmission bands. In this first paper resulting from the survey, we report on the discovery of the galaxy counterpart of the z_abs = 2.354 DLA towards the z=2.926 quasar Q2222\$-0946. This DLA is amongst the most metal-rich z>2 DLAs studied so far at comparable redshifts and there is evidence for substantial depletion of refractory elements onto dust grains. We measure metallicities from ZnII, SiII, NiII, MnII and FeII of -0.46+/-0.07, -0.51+/-0.06, -0.85+/-0.06, -1.23+/-0.06, and -0.99+/-0.06, respectively. The galaxy is detected in the Lyman-alpha, [OIII] lambda4959,5007 Halpha emission lines at an impact parameter of about 0.8 arcsec (6 kpc at z_abs = 2.354). We infer a star-formation rate of 10 M_sun yr^-1, which is a lower limit due to the possibility of slit-loss. Compared to the recently determined Halpha luminosity function for z=2.2 galaxies the DLA-galaxy counterpart has a luminosity of L~0.1L^*_Halpha. The emission-line ratios are 4.0 (Lyalpha/Halpha) and 1.2 ([OIII]/Halpha). The Lyalpha line shows clear evidence for resonant scattering effects, namely an asymmetric, redshifted (relative to the systemic redshift) component and a much weaker blueshifted component. The fact that the blueshifted component is relatively weak indicates the presence of a galactic wind. The properties of the galaxy counterpart of this DLA is consistent with the prediction that metal-rich DLAs are associated with the most luminous of the DLA-galaxy counterparts.
 équipe(s) de recherche : APC - AHE
 Domaine : Physique/Astrophysique/Cosmologie et astrophysique extra-galactiquePlanète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique
 Mots Clés : galaxies – formation – galaxies – high-redshift – ISM – quasars – absorption lines – individual – Q 2222-0946 – cosmology – observations
 Lien vers le texte intégral : http://fr.arXiv.org/abs/1002.4626
 hal-00708878, version 1 http://hal.archives-ouvertes.fr/hal-00708878 oai:hal.archives-ouvertes.fr:hal-00708878 Contributeur : Paolo Goldoni <> Soumis le : Samedi 16 Juin 2012, 10:46:18 Dernière modification le : Samedi 16 Juin 2012, 16:48:08