On the sizes of z ≥ 2 damped Lyα absorbing galaxies

Abstract

Recently, the number of detected galaxy counterparts of z > 2 damped Lyman α absorbers in quasi-stellar object (QSO) spectra has increased substantially so we today have a sample of 10 detections. Møller et al. in the year 2004 made the prediction, based on a hint of a luminosity-metallicity relation for DLAs, that HI size should increase with increasing metallicity. In this Letter we investigate the distribution of impact parameter and metallicity that would result from the correlation between galaxy size and metallicity. We compare our observations with simulated data sets given the relation of size and metallicity. The observed sample presented here supports the metallicity-size prediction: the present sample of DLA galaxies is consistent with themodel distribution. Our data also show a strong relation between impact parameter and column density of HI. We furthermore compare the observations with several numerical simulations and demonstrate that the observations support a scenario where the relation between size and metallicity is driven by feedback mechanisms controlling the star formation efficiency and outflow of enriched gas. © 2012 Dark Cosmology Centre Monthly Notices of the Royal Astronomical Society © 2012 RAS.