Cake Talk by Patricia Bolan from UC Davis
Some of the most important questions surrounding the Epoch of Reionzation (EoR) relate to the determination of a detailed timeline on how the neutral hydrogen fraction, x_HI, of the intergalactic medium (IGM) evolved and which sources were responsible for this phase change. This work uses observations of Lyman Break Galaxies (LBGs) from the EoR to put constraints on the evolution of x_HI. We also take a closer look at some of these LBGs to explore characteristics of galaxies which likely contributed to reionization. Our sample consists of almost 300 spectroscopically observed, intrinsically faint LBG candidates from z ~ 5 - 8.2. With luminosities ranging from a few L* down to 0.001L*, the average luminosity is 0.1-0.3L*, representing typical reionization era galaxies which may have done the bulk of the ionizing and are typically less biased probes of the state of the IGM than brighter galaxies. I will present new constraints on x_HI using an impressive sample of faint galaxy candidates with spectroscopy from Keck/DEIMOS-MOSFIRE. We compare the Lyman-alpha equivalent width distribution of these LBG samples to forward models of realistic inhomogeneous IGM simulations in order to infer x_HI at z ~ 6.7 and z ~ 7.6. I will also discuss current work and observations exploring the interstellar medium of typical EoR galaxies through constraints on CIII] emission.