Metallicities and dust content of proximate damped Lyman α systems in the Sloan Digital Sky Survey

摘要: Composite spectra of 85 proximate absorbers [log N(H I) > 20 cm -2 and velocity difference between the absorption emission redshifts, ΔV 6000 km s -1 , with further sub-samples to investigate metal-line dependence on QSO luminosity. Low (e.g. Si II Fe n) high ionization iv C IV) species alike have equivalent widths (EWs) that are larger by factors 1.5-3 in spectrum. The EWs show an even stronger if only highest neutral hydrogen column density 20.7] considered. We conclude damped Lyman α systems (PDLAs) generally higher metallicities than intervening absorbers, enhancement being a function both I). It is also found near QSOs lower rest-frame UV luminosities significantly metal lines. speculate luminosity may had their star formation prematurely quenched. There no evidence for Lyα trough composite Finally, we search signature dust reddening PDLAs, based analysis continuum slopes relative control sample, determine limit E(B - V) < 0.014 Small Magellanic Cloud extinction curve. This work provides empirical motivation distinguishing DLAs establishes connection environment galaxy properties at redshifts.