学术报告—The many faces of the galactic halos near and far

报告摘要

Satellite galaxies and their stripped stars by the host dark halo potential, which form the outer stellar halo of the central galaxy, are of particular interests for cosmology and galaxy evolution studies. In the nearby Universe, the internal stellar kinematics of nearby satellite galaxies and of Milky Way (MW) stellar halo can be resolved. The best constrained dark matter distributions based on stellar kinematics are closely related to a few near field cosmological problems. While many recent studies have pin pointed evidences that baryonic physics can explain these so-called problems, and uncertainties associated with the dynamical modeling method can affect the conclusion. In this talk, I will talk about dynamical modeling based on stellar kinematics of nearby satellite galaxies and MW halo stars, to recover the dark matter distribution in the local Universe. I will show our attempts of testing dynamical model accuracy of traditional methods, development of new data-driven models and application of the models to the most recent DESI observations. Going further to the more distant Universe, the abundance of satellite galaxies and the low surface brightness stellar halos around the central galaxy, as formed by these satellites, are usually studied through deep photometric data. I will present our measurements of the satellite luminosity function down to V-band absolute magnitude of about -10, by counting faint photometric satellites around spectroscopically identified central galaxies, with comparisons against our MW satellite system. I will show evidences that the MW satellite galaxies are statistically atypical at the faint end, and our local Universe is an under-dense region. In the end, if time allows, I plan to show how the surface brightness profiles for the stellar halos of more distant galaxies can be measured by stacking deep galaxy imaging data after PSF corrections.  

报告人简介

I mainly work on galaxy formation and evolution, galaxy-halo connection and dynamical modelling of the MW Galaxy and dwarf galaxies. When individual stars are mainly used as dynamical tracers for galactic studies in my research, I have growing interests towards individual stars. More recently, I have been happily working on a few projects with students and postdocs, associated with proper motion and distance measurements for MW stars, and binary fractions of stars in dwarf galaxies. I got my PhD. at Shanghai Astronomical Observatory in 2012. Afterwards, I worked as a postdoc at Durham University (Durham Junior Research Fellowship), and at Kavli-IPMU (Tokyo University), before joining the Astronomy department of Shanghai Jiaotong University in 2019.