2009AJ....138.1609M

We report the first discovery of a QSO damped Lyα system (DLA) by the Galaxy Evolution Explorer (GALEX) satellite. The system was initially identified as an Mg II absorption-line system (z_abs= 1.028) in the spectrum of Sloan Digital Sky Survey (SDSS) QSO J0203-0910 (z_em= 1.58). The presence of unusually strong absorption due to metal lines of Zn II, Cr II, Mn II, and Fe II clearly suggested that it might be a DLA with N_ H I_≥ 2 x 10²⁰ atoms/cm2. Follow-up GALEX NUV grism spectroscopy confirms that the system exhibits a DLA absorption line, with a measured H I column density of N_ H I_= 1.50±0.45x10²¹ atoms/cm2. By combining the GALEX N _ H I_determination with the SDSS spectrum measurements of unsaturated metal-line absorption due to Zn II, which is generally not depleted onto grains, we find that the system's neutral-gas-phase metal abundance is [Zn/H] = -0.70 ±0.22, or ~20% solar. By way of comparison, although this system has one of the largest Zn⁺ column densities, its metal abundances are comparable to other DLAs at z ~ 1. Measurements of the abundances of Cr, Fe, and Mn help to further pin down the evolutionary state of the absorber.