A SINFONI integral field spectroscopy survey for galaxy counterparts to damped Lyman α systems - I. New detections and limits for intervening and associated absorbers

Detailed studies of damped and sub-damped Lyman alpha systems (DLAs), the galaxies probed by the absorption they produce in the spectra of background quasars, rely on identifying the galaxy responsible for the absorber with more traditional methods. Integral field spectroscopy provides an efficient way of detecting faint galaxies near bright quasars, further providing immediate redshift confirmation. Here, we report the detection of H alpha emission from a DLA and a sub-DLA galaxy among a sample of six intervening quasar absorbers targeted. We derive F(H alpha) = 7.7 +/- 2.7 x 10(-17) erg s(-1) cm(-2) (SFR = 1.8 +/- 0.6M(circle dot) yr(-1)) at impact parameter b = 25 kpc towards quasar Q0302 - 223 for the DLA at z(abs) = 1.009 and F(H alpha) = 17.1 +/- 6.0 x 10(-17) erg s(-1) cm(-2) (SFR = 2.9 +/- 1.0M(circle dot) yr(-1)) at b = 39 kpc towards Q1009 - 0026 for the sub-DLA at z(abs) = 0.887. These results are in line with low star formation rates previously reported in the literature for quasar absorbers. We use the [N II]lambda 6585/H alpha ratio to derive the H II emission metallicities and compare them with the neutral gas HI absorption metallicities derived from high-resolution spectra. In one case, the absorption metallicity is actually found to be higher than the emission line metallicity. For the remaining objects, we achieve 3 sigma limiting fluxes of the order F(H alpha) similar to 10(-17) erg s(-1) cm(-2) (corresponding to SFR similar to 0.1 M-circle dot yr(-1) at z similar to 1 and similar to 1 M-circle dot yr(-1) at z similar to 2), i.e. among the lowest that have been possible with ground-based observations. We also present two other galaxies associated with C IV systems and serendipitously discovered in our data.