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We present the results of our automatic search for proximate dampedLy$\alpha$ absorption (PDLA) systems in the quasar spectra from the SloanDigital Sky Survey Data Release 12. We constrain our search to those PDLAslying within 1500 km s$^{-1}$ from the quasar to make sure that the broad DLAabsorption trough masks most of the strong Ly$\alpha$ emission from the broadline region (BLR) of the quasar. When the Ly$\alpha$ emission from the BLR isblocked by these so-called eclipsing DLAs, narrow Ly$\alpha$ emission from thehost galaxy could be revealed as a narrow emission line (NEL) in the DLAtrough. We define a statistical sample of 399 eclipsing DLAs withlog$N$(HI)$\ge$21.10. We divide our statistical sample into three subsamplesbased on the strength of the NEL detected in the DLA trough. By studying thestacked spectra of these subsamples, we found that absorption from highionization species are stronger in DLAs with stronger NEL in their absorptioncore. Moreover, absorption from the excited states of species like SiII arealso stronger in DLAs with stronger NEL. We also found no correlation betweenthe luminosity of the Ly$\alpha$ NEL and the quasar luminosity. Theseobservations are consistent with a scenario in which the DLAs with stronger NELare denser and physically closer to the quasar. We propose that these eclipsingDLAs could be the product of the interaction between infalling and outflowinggas. High resolution spectroscopic observation would be needed to shed somelight on the nature of these eclipsing DLAs.

Eclipsing damped Ly$\alpha$ systems in the Sloan Digital Sky Survey Data Release 12