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On the sizes of z≳2 damped Lyinline image absorbing galaxies


  • Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Based on observations collected at the European Organization for Astronomical Research in the Southern hemisphere, Chile, under programmes 084.A-0303(A) and 086.A-0074(A).



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 H i 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 the model distribution. Our data also show a strong relation between impact parameter and column density of H i. 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.