The mass of our Milky Way

By starting with a summary of the measured virial mass of our Milky Way in the past 20 years and showing the large scatter among different measurements/methods, I will mainly talk about the uncertainties behind the phase-space distribution function and the spherical Jeans Equation method of measuring our Milky Way halo mass using luminous dynamical tracers. By applying the dynamical method to galaxies and dark matter haloes in numerical simulations, we test the model assumptions and systematic errors. The invalid functional form of analytical phase-space distribution functions can introduce systematic bias to the recovered halo mass and concentration. And by using the spherical Jeans Equation, we show all methods based on the steady state and spherical assumptions suffer from a limiting precision of the mass measurement up to a factor of two to three, when star particles are used as dynamical tracers and when tangential velocities are available. Tracer objects with large true degrees of freedom (less phase-correlated), extending out to large distances and with proper motion measurements are important for properly recovering the mass of our Milky Way.

Speaker: 
Dr. Wenting WANG @ Shanghai Jiaotong University
Location: 
Zoom Meeting ID: 762 615 248
Time: 
Wed, 2020-04-01 14:00 to 14:30