Lyman Limit System Metallicity at z~3.5
We initially studied Lyman Limit Systems (LLSs, absorbers that are optically thick photons that ionize neutral hydrogen) at high redshift to look for some with low-metallicities, motivated by simulations predicting these are how accretion may manifest. Having found these, we went back and looked at the full population of LLSs. Surprisingly, they all seem to be metal-poor, with enrichment closer to that of the diffuse intergalactic medium than the more dense Damped Lyman Alpha absorbers (DLAs).
Glidden, Cooper+ 2016
Galaxy-Absorber Pairs at z=3-4
We are in the process of identifying redshifts of galaxies at close projected distances to quasar sightlines known to be rich in Mg II absorption systems, to match absorbers with associated galaxies. The resulting dataset will compare absorber properties with host galaxy morphologies, orientations, and distances, and will connect with a large body of work with similar pairs at low redshifts.
Ionization and Enrichment at z>6
Using infrared and optical spectra two extrememly bright quasars at redshifts z>6, I am measuring the absorption signatures of atomic species in different ionization states to constrain the metallicity and ionization profile of very high redshift absorbers, while hopefully learning something about reionization.