A SINFONI integral field spectroscopy survey for galaxy counterparts to damped Lyman α systems - III. Three additional detections★

Abstract

We report three additional Spectrograph for Integral Field Observations in the Near Infrared (SINFONI) detections of Hα emission line from quasar absorbers, two of which are new identifications. These were targeted among a sample of systems with and metallicities measured from high‐resolution spectroscopy. The detected galaxies are at impact parameters ranging from 6 to 12 kpc from the quasar’s line of sight. We derive star formation rates (SFRs) of a few M⊙ yr−1 for the two absorbers at zabs∼ 1 and SFR = 17 M⊙ yr−1 for the damped Lyman α system (DLA) at zabs∼ 2. These three detections are found among a sample of 16 DLAs and sub‐DLAs (five at zabs∼ 1 and seven at zabs∼ 2). For the remaining undetected galaxies, we derive flux limits corresponding to SFR < 0.1–11.0 M⊙ yr−1 depending on redshift of the absorber and depth of the data. When combined with previous results from our survey for galaxy counterparts to H i‐selected absorbers, we find a higher probability of detecting systems with higher metallicity as traced by dust‐free [Zn/H] metallicity. We also report a higher detection rate with SINFONI for host galaxies at zabs∼ 1 than for systems at zabs∼ 2. Using the [N ii]/Hα ratio, we can thus compare absorption and emission metallicities in the same high‐redshift objects, more than doubling the number of systems for which such measures are possible.

Galaxy counterparts of metal-rich damped Lyα absorbers: the case of J205922.4−052842★

“…Smith, Cohen & Bradley 1986;Møller & Warren 1993;Kulkarni et al 2001;Fumagalli et al 2014) and integral field spectroscopy (e.g. Christensen et al 2007;Péroux et al 2011;Bouché et al 2012;Jorgenson & Wolfe 2014). Despite the much larger number of systems being observed, between 1986 and 2010 the galaxy counterparts of only two bona fide DLAs were identified (Møller, Fynbo & Fall 2004; but see also Krogager et al 2012;Christensen et al 2014).…”

“…A high A V would lead to an underestimation of the Lyα flux, and thus of the SFR, but this number is already a lower limit. VLT/SINFONI integral field spectroscopy of the environment of DLA-2059 reported by Péroux et al (2012) yields an upper limit of SFR < 1.3 M yr −1 based on the absence of Hα. The SFR can therefore be constrained to 0.40 < SFR < 1.3 M yr −1 .…”

Atomic and molecular absorption in redshifted radio sources

“…(ii) Very few DLAs have been detected in Lyman-α or Hα emission (Möller et al 2004;Fynbo et al 2010Fynbo et al , 2011Noterdaeme et al 2012;Péroux et al 2012), both tracers of star formation.…”

Witnessing galaxy assembly in an extended z≈3 structure

“…Despite decades of searches, only tens of DLAs have been associated directly to counterparts in emission, particularly thanks to recent campaigns (e.g. Møller et al 2004;Fynbo et al 2010;Noterdaeme et al 2012;Péroux et al 2012;Fynbo et al 2013;Neeleman et al 2017;Krogager et al 2017). This low detection rate across the entire DLA population is generally attributed to the difficulties of imaging faint emission from stellar populations or hydrogen recombination lines at high redshifts.…”

“…Péroux et al 2012;Neeleman et al 2017), the deployment of the Multi Unit Spectroscopic Explorer (MUSE; Bacon et al 2010) at the Very Large Telescope (VLT) represents a breakthrough to address the long-standing issue of connecting DLAs to galaxy counterparts. Indeed, MUSE allows us to image Lyα emission within ≈250 kpc from the position of known DLAs to flux limits of ≈ 10 −18 erg s −1 cm −2 in exposure times of only few hours, thus enabling deep searches of DLA host galaxies without the need of pre-selecting targets for spectroscopic follow-up observations.…”