# IAUS379: Dynamical Masses of Local Group Galaxies

20-24 March 2023
Haus H, Telegrafenberg
Europe/Berlin timezone

## Revisiting mass estimates of the Milky Way, of M31, and of some spiral galaxies

21 Mar 2023, 13:09
2m
Haus H, Telegrafenberg

#### Haus H, Telegrafenberg

Potsdam, Germany
Poster SESSION 2 : Sizes, Masses, and Formation histories of the Milky Way and of Andromeda

### Speaker

Yongjun JIAO (Paris Observatory)

### Description

We estimate that the mass of the Milky Way (MW) is in the range of 2 to 15 $\times 10^{11} M_\odot$. It results from an analysis of the rotation curve (RC) from Gaia DR2 and using different profiles for baryon and dark matter (DM, including NFW & Einasto profile). The lower limit 2 $\times 10^{11} M_\odot$ corresponds to the Keplerian slope of RC at large radii. There were no major mergers in the MW since 9 $\sim$10 Gyr ago and then the dynamical mass is well established from its RC.

However, most distant galaxies have been found in the process of merging, which perturbs the motion of stars and gas. Thus it is essential to determine if the galaxy outskirts could be at equilibrium after the merger epoch. Using a library of the simulations of galaxy major-merger (including M31), we will study the criteria for determining the relaxation of galactic disks. We will apply these criteria to the nearby spiral galaxies and determine the relaxation time scale and radius. Then we can measure robust dynamical masses within a given radius.

Do you plan to attend the symposium in-person or virtually? in-person

### Primary author

Yongjun JIAO (Paris Observatory)

### Presentation Materials

There are no materials yet.