Choose timezone
Your profile timezone:
HEP Journal Club Seminar
Constraining dark matter density profiles with dwarf galaxy kinematics: the 2D and the 6D story
by
→
Pacific/Honolulu
Room 112 (Watanabe Hall)
Room 112
Watanabe Hall
32
Description
The stellar kinematics in dwarf galaxies can provide a wealth of information about its underlying dark matter distribution. Line-of-sight velocity dispersion measurements from six classical dwarf galaxies can be used to show that axion-like particles with masses of order m ~ 10^(−22) eV are inconsistent with the potential distribution in classical dwarf galaxies unless the hierarchical assembly of the Milky Way did not trace the mean evolution of Milky Way size halos. However, line-of-sight velocity constraints alone are subject to degeneracies between central dark matter density and stellar velocity anisotropy. Using both line-of-sight velocities and proper motions from Gaia DR3 data, we examine the kinematics of the central core of the Sagittarius (Sgr) dwarf spheroidal galaxy. We extract a sample of bright stars that are high-probability members of Sgr and obtain a velocity anisotropy of βa=−2.24±1.99, which implies a system with tangentially-biased orbits. However without accurate distances to these stars, a 6D Jeans analysis cannot be performed. From Gaia only 5D data plus mock distances, we project that the data will significantly improve upon measurements of the log-slope of the dark matter density profile and the stellar velocity anisotropy. Tests with mock distance data show an improvement of anisotropy errors of approximately an order of magnitude, and log slope at the half light radius of approximately half an order of magnitude, indicating stronger future constraints on dark matter density profiles.