Reconciling the Metallicity Distributions of Gamma-ray Burst, Damped Lyman-alpha, and Lyman-break Galaxies at z=3

摘要

We test the hypothesis that the host galaxies of long-duration gamma-raybursts (GRBs) as well as quasar-selected damped Lyman-alpha (DLA) systems aredrawn from the population of UV-selected star-forming, high-z galaxies(generally referred to as Lyman-break galaxies). Specifically, we compare themetallicity distributions of the GRB and DLA populations to simple models wherethese galaxies are drawn randomly from the distribution of star-forminggalaxies according to their star-formation rate and HI cross-sectionrespectively. We find that it is possible to match both observationaldistributions assuming very simple and constrained relations betweenluminosity, metallicity and HI sizes. The simple model can be tested byobserving the luminosity distribution of GRB host galaxies and by measuring theluminosity and impact parameters of DLA selected galaxies as a function ofmetallicity. Our results support the expectation that GRB and DLA samples, incontrast to magnitude limited surveys, provide an almost complete census of z=3star-forming galaxies that are not heavily dust-obscured.