The ESO UVES Advanced Data Products quasar sample – V. Identifying the galaxy counterpart to the sub-damped Lyα system towards Q 2239-2949

Abstract

Gas flows in and out of galaxies are one of the key unknowns in todays'\ngalaxy evolution studies. Because gas flows carry mass, energy and metals, they\nare believed to be closely connected to the star formation history of galaxies.\nMost of these processes take place in the circum-galactic medium (CGM) which\nremains challenging to observe in emission. A powerful tool to study the CGM\ngas is offered by combining observations of the gas traced by absorption lines\nin quasar spectra with detection of the stellar component of the same\nabsorbing-galaxy. To this end, we have targeted the zabs=1.825 sub-Damped\nLy-alpha absorber (sub-DLA) towards the zem=2.102 quasar 2dF J 223941.8-294955\n(hereafter Q2239-2949) with the ESO VLT/X-Shooter spectrograph. Our aim is to\ninvestigate the relation between its properties in emission and in absorption.\nThe derived metallicity of the sub-DLA with log N(HI) = 19.84+/-0.14 cm-2 is\n[M/H] >-0.75. Using the Voigt profile optical depth method, we measure\nDelta_v90(FeII)=64 kms-1. The sub-DLA galaxy counterpart is located at an\nimpact parameter of 2."4+/-0."2 (20.8+/-1.7 kpc at z = 1.825). We have detected\nLy-alpha and marginal [OII] emissions. The mean measured flux of the Ly-alpha\nline is F(Ly-alpha) ~ 5.7x10^-18 erg s-1 cm-2 A-1, corresponding to a dust\nuncorrected SFR of ~ 0.13 M(solar) yr-1.\n