SHAO Astrophysics Colloquium

Title: The Cosmic Ray-Dominated Circumgalactic Medium

Speaker: Suoqing Ji （California Institute of Technology）

Time: 3:00 pm, Nov. 28th (Thursday)

Location: Lecture Hall, 3rd floor

Abstract: Recent observations suggest that large quantities of cool gas are found in the circumgalactic medium (CGM) of the galaxy halo, with temperatures of a few 10^4 K. In addition, detections of highly-ionized oxygen (O VI) indicate the existence of warm gas at a few 10^5 K around star-forming galaxies. However, the origin and stability of the combined cool, warm and hot multiphase CGM are not fully understood yet. With the FIRE-2 simulations in which cosmic ray physics is incorporated, we have found that Milky Way-mass galaxy halos at low redshifts could potentially be dominated by cosmic ray pressure rather than ordinary thermal gas pressure. This insight fundamentally reshapes our understanding of the physical states of the multiphase CGM, and may help solve long-standing puzzles such as the survival of the ubiquitous cool gas, and the usually under-predicted O VI.

SHAO Astrophysics Colloquium

Title: COSMOLOGY FROM GRAVITATIONAL LENSING WITH THE KILO-DEGREE SURVEY

Speaker: Konrad Kuijken, Leiden Observatory

Time: 3:00 pm, Nov. 27th (Wednesday)

The Lambda-CDM model is a very succesful description of the universe. It predicts how large-scale structures form and grow with time, leading to the present-day population of clustered galaxies.

In this talk I will describe how we are testing this model with gravitational lensing measurements of the large-scale distribution of matter, in particular from the Kilo-Degree Survey, a project to map 1300 square degrees of sky using the VLT Survey Telescope at ESO in Chile.