Circumgalactic Medium and Large Scale Structure at z=2 Traced by Lya Emission
Speaker: Haibin Zhang
Abstract:
In current pictures of galaxy formation and evolution, galaxies are closely related to their surrounding circumgalactic medium (CGM) and large scale structure (LSS). To investigate the CGM and LSS at high-z, I will introduce our “MAMMOTH-Subaru” paper series that study ~3300 Lyα emitters (LAEs) and ~120 Lyα blobs (LABs; luminous and massive LAEs) at z=2 selected with Subaru/HSC data. Our main results are: 1. We stack our LAEs to identify the faint Lyα emission in CGM (Lyα halo; LAH). Our LAH is detected till ~100 kpc at the 2σ level and likely extended to ~200 kpc. We show that more massive LAEs generally have more extended (flatter) LAHs. 2. We find that most (~70%) LABs locate in overdense environments. A unique protocluster region (~40*20 cMpc^2) contains 12 LABs, showing an extremely high LAB number density (>2 times higher than the SSA22 field). We calculate the angular correlation functions of LAEs and LABs, and suggest that LABs are more clustered and likely reside in more massive dark matter halos than LAEs. 3. We calculate the Lyα luminosity function at z=2 and demonstrate an observational approach to measure the cosmic variance. We find that our measurements cannot be explained by previous simulations, and that LAEs likely have a larger cosmic variance than general star-forming galaxies.