Colloquium on Sep. 11, 2025

The many faces of galactic halos near and far

Speaker: Wenting Wang (SJTU)

Venue: SWIFAR Building 2111

Time: 16:00 PM, Thursday, Jul. 17, 2025

Abstract:

Satellite galaxies and their stripped stars by the host dark halo, which form the outer stellar halo of the central galaxy, are of particular interests for galaxy evolution and cosmology studies. In the nearby Universe, the internal stellar kinematics of Milky Way (MW) satellite galaxies and MW outer 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 including the core-cusp debate. While many recent studies have pin pointed evidences that baryonic physics can explain such near field problems, uncertainties associated with the dynamical modeling method can affect the conclusion. I will show our attempts of testing dynamical model accuracy of traditional methods, development of new models and application of the models to the most recent DESI observations, and connections to the core-cusp problem. A few on-going projects of measuring MW stellar halo shape and binary identification through line-of-sight velocity variations will be advertised. Going further to the more distant Universe, satellite galaxies and the low surface brightness stellar halo around the central galaxies are usually studied through deep photometry. Measurements of the satellite luminosity function down to r-band absolute magnitude of about -7 or stellar mass of 10^5.5 solar mass will be presented, by counting faint photometric satellites around spectroscopically identified central galaxies. Comparisons are performed with our MW satellites. Evidences will be shown that the MW satellite galaxies are statistically atypical at the faint end, because our local Universe is an under-dense region. In the end, if only 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 deconvolutions.

Report PPT:  SWIFAR_Wenting Wang.pdf