MATs (Monday Afternoon Talks), 10/02/2023 — Speaker: Zhihui Li

Monday October 2, 2023 3:00 pm

MATs (Monday Afternoon Talks)

3:00pm – 3:30pm, Zhihui Li

Unveiling the Multiphase, Clumpy Structure of the Circumgalactic Medium of High-z Galaxies
In this talk, I will present our recent progress on constraining the physical properties of the ”cool” (T ~ 104K) phase of the circumgalactic medium (CGM) via modeling Lya emission and low-ionization-state (LIS) metal absorption lines. We developed a new way of modeling the radially-varying Lya profiles in a spatially-resolved manner using the Lya radiative transfer (RT) code, tlac. Our model successfully reproduced the radial trends of several Lyá spectral properties, including the peak flux ratio, peak separation and flux at the line center, which can all be understood from an RT perspective. We have also developed a new semi-analytic model, ALPACA, for modeling metal absorption lines that emerge from a clumpy galactic environment. ALPACA is able to simultaneously reproduce the “down-the-barrel” absorption line profile and the equivalent widths of absorption measured at different impact parameters of a sample of high-z star-forming galaxies and derive reasonable constraints on important properties of the clumpy medium, including clump kinematics, clump volume filling factor, and clump number density profile. Lastly, I will show how the joint modeling of Lya emission and LIS absorption lines can potentially break particular parameter degeneracies and eventually help us unveil the intricate structure of the CGM.




Hosts: Minghao Yue, Daniele Michilli


  • Zhihui Li, CalTech