A glance at the host galaxy of high-redshift quasars using strong damped lyman-α systems as coronagraphs

Abstract

We searched quasar spectra from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) for the rare occurrences where a strong damped Lyman-Á absorber (DLA) blocks the Broad Line Region emission from the quasar and acts as a natural coronagraph to reveal narrow LyÁ emission from the host galaxy. We define a statistical sample of 31 DLAs in Data Release 9 (DR9) with log N(H i) iÝ 21.3 cm.2 located at less than 1500 km s.1 from the quasar redshift. In 25% (8) of these DLAs, a strong narrow LyÁ emission line is observed with flux i"25 iÁ 10.17 erg s.1 cm.2 on average. For DLAs without this feature in their troughs, the average 3-Ò upper limit is. © ESO 2013.