2016MNRAS.460..634S

Using VLT/X-shooter, we searched for emission line galaxies associated with four damped Lyman α systems (DLAs) and one sub-DLA at 2.73 <=z <=3.25 towards QSO J2358+0149. We detect [O iii] emission from a 'low-cool' DLA at z_abs=2.9791 (having log N(H i)=21.69±0.10, [Zn/H]=-1.83±0.18) at an impact parameter of, ρ ∼ 12 kpc. The associated galaxy is compact with a dynamical mass of (1-6) x 10^9 M_☉, very high excitation ([O iii]/[O ii] and [O iii]/[Hβ] both greater than 10), 12+[O/H]<=8.5 and moderate star formation rate (SFR <=2 M_☉ yr^-1). Such properties are typically seen in the low-z extreme blue compact dwarf galaxies. The kinematics of the gas is inconsistent with that of an extended disc and the gas is part of either a large scale wind or cold accretion. We detect Lyα emission from the z_abs=3.2477 DLA [having log N(H i)=21.12±0.10 and [Zn/H]=-0.97±0.13]. The Lyα emission is redshifted with respect to the metal absorption lines by 320 km s^-1, consistent with the location of the red hump expected in radiative transport models. We derive SFR ∼0.2-1.7 M_☉ yr^-1 and Lyα escape fraction of >=10 per cent. No other emission line is detected from this system. Because the DLA has a small velocity separation from the quasar (∼500 km s^-1) and the DLA emission is located within a small projected distance (ρ < 5 kpc), we also explore the possibility that the Lyα emission is being induced by the QSO itself. QSO-induced Lyα fluorescence is possible if the DLA is within a physical separation of 340 kpc to the QSO. Detection of stellar continuum light and/or the oxygen emission lines would disfavour this possibility. We do not detect any emission line from the remaining three systems.