Evolution of the Cool Gas in the Circumgalactic Medium (CGM) of Massive Halos -- A Keck Cosmic Web Imager (KCWI) Survey of Ly$\alpha$ Emission around QSOs at $z\approx 2$

Zheng Cai, Sebastiano Cantalupo, J. Xavier Prochaska +6

Motivated by the recent discovery of the near-ubiquity of Ly$\alpha$ emission around $z\gtrsim 3$ QSOs, we performed a systematic study of QSO circumgalactic Ly$\alpha$ emission at $z\appro…