We have initiated a survey using the newly commissioned X-shooter spectrograph to target candidate relatively metal-rich damped
Lyα absorbers (DLAs). Our rationale is that high-metallicity DLAs due to the luminosity-metallicity relation likely will have
the most luminous galaxy counterparts. In addition, the spectral coverage of X-shooter allows us to search for not only Lyα
emission, but also rest-frame optical emission lines. We have chosen DLAs where the strongest rest-frame optical lines ([O
ii], [O iii], Hβ and Hα) fall in the near-infrared atmospheric transmission bands. In this first paper resulting from the
survey, we report on the discovery of the galaxy counterpart of the zabs= 2.354 DLA towards the z= 2.926 quasar Q 2222−0946.
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 on to dust grains. We measure metallicities from Zn ii, Si ii, Ni ii, Mn ii and Fe ii 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 Lyα,
[O iii]λλ4959, 5007 and Hα emission lines at an impact parameter of about 0.8 arcsec (6 kpc at zabs= 2.354). Based on the
Hα line, we infer a star formation rate of 10 M⊙ yr−1, which is a lower limit due to the possibility of slit loss. Compared
to the recently determined Hα luminosity function for z= 2.2 galaxies, the DLA-galaxy counterpart has a luminosity of L∼ 0.1L*Hα.
The emission-line ratios are 4.0 (Lyα/Hα) and 1.2 ([O iii]/Hα). In particular, the Lyα 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.
of the galaxy counterpart of this DLA are consistent with the prediction that metal-rich DLAs are associated with the most
luminous of the DLA-galaxy counterparts.