DR. RAVI JOSHI

Strong foreground absorption features from singly ionized magnesium (Mg II) are commonly observed in the spectra of quasars and are presumed to probe a wide range of galactic environments. Here we present a detailed analysis of ~80000 MgII absorbers using SDSS/BOSS survey to probe their nature, star formation rate and association of Mg II absorbers with DLAs in presence of strong Fe II absorption. The difference in the number density (dN/dz) evolution as well as in the emission line ([O II] and [O III]) properties in the stacked spectra have shown that the two sets with R parameter (R = EW[Fe II] / EW[Mg II]) less or more than 0.45 represent the two physically different populations of absorbers. Our stack results imply that the galaxies causing Mg II absorption are typically of sub-L*, with luminosity range of 0.01 0.04L*. However, we find that the direct detections (~122 candidates) of the [O II], [O III] lines from intervening star-forming galaxies probe a luminosity up to 0.05-2L*. Finally, the speaker will present efforts to identifying the galaxy counterparts of such strong Mg II absorbers at low-z.