Lunch talk on Nov. 18th, 2019

Constraining the Milky Way Mass Profile with Phase-Space Distribution of Satellite Galaxies

Speaker:Zhaozhou Li (STJU)

Venue:Room 2111, SWIFAR Building

Time:12:30 PM, Monday, 18th November, 2019

Abstract:

The Milky Way (MW) mass profile is crucial to astrophysical studies at various scales. We estimate the mass and concentration of the MW halo using the kinematic data of its satellite galaxies, including the latest measurements from Gaia DR2. Our 6D phase-space distribution function (DF) of satellite kinematics is constructed from cosmological simulations. It allows us to infer the halo mass efficiently and without bias, and handle the selection function and measurement errors rigorously in the Bayesian framework. Applying our DF from the EAGLE simulation to 28 satellites, we obtain an MW halo mass of $M=1.23_{-0.18}^{+0.21}\times 10^{12} M_\odot$ and a concentration of $c=9.4_{ -2.1}^{ +2.8}$. The inferred mass profile is consistent with previous measurements, but with better precision and reliability due to the improved methodology and data. Further improvement is illustrated by combining satellite data and additional constraints from stellar rotation curves. We examine the dependence of our method on simulations by comparing the results from the hydrodynamics-based EAGLE simulation and the semi-analytical model based on the dark-matter-only simulation Millennium II. We confirm that the EAGLE simulation provides a better match to the observed satellite kinematics. Using our DF and MW potential, we provide much more precise estimates to kinematics for those satellites with poor current measurements.

Report PPT:SWIFAR_Zhaozhou Li.pdf