Oral Presentation
Observational Evidence for Large-Scale Gas Heating in a Galaxy Protocluster at z=2.30
Presenter: Chenze Dong (Kavli IPMU)
We report large-scale gas heating in a galaxy protocluster (COSTCO-I) at z=2.30. COSTCO-I is well-detected in a constrained galaxy-based simulation, COSTCO, but absent in the Lyman-alpha tomography survey, CLAMATO. The difference hints the deviation from universal relation at z~2 between matter overdensity and Lyman-alpha optical depth (also known as fluctuating Gunn-Peterson approximation; FGPA) in the vicinity of COSTCO-I. We further generate 1140 instances of mock CLAMATO-like transmission data from 57 realizations of COSTCO density fields by applying FGPA and incorporating the effects of finite sightline sampling, pixel noise, and Wiener filtering. The comparison between COSTCO-FGPA and CLAMATO averaged in 15 Mpc/h reveals that COSTCO-I region is consistently more transparent in CLAMATO ((p=0.0026, or 2.79 σ significance)), thus implies the large-scale heating presumably due to AGN jet-feedback or early gravitational shock heating. This is the first known large-scale region of the IGM that is transitioning from the optically-thin photoionized regime at Cosmic Noon, to eventually collapse into the intra-cluster medium by z=0. Future observations of similar structures will shed light into the growth of the ICM and allow constraints on AGN feedback mechanisms.
asiaa.sinica.edu.tw