Ryan Cooke, UK ()
"UM 673: A unique system to study the properties of Damped Lyman-alpha Systems"
Abstract. The sightline to the brighter member of the gravitationally lensed quasar pair UM 673A,B intersects a damped Lyman-alpha system (DLA) at z ~ 1.6.The neighbouring sightline, however, exhibits a drop in neutral Hydrogencolumn density by at least a factor of 400, over just 3 kpc. By reassessing this new case together with published data on other QSO pairs,we constrain the typical size of these neutral gas reservoirs at moderate redshifts. Furthermore, we detect a weak and narrow Lyman-alpha emission line which we attribute to star formation activity in the host galaxy of the DLA. We also find the DLA in UM 673A to be metal-poor, with an overall metallicity Z_DLA ~ 1/30 Z_solar. By studying the properties of these low-metallicity systems at high redshift, we may uncover some important clues into the nucleosynthesis from some of the first structures to formin the Universe.
Held in the AAO Conference room at 03:30 PM on Wednesday, 12 May 2010back