| Popis: |
I will discuss three sample Roman Telescope near-field cosmology science cases: (1) Milky Way (MW) halo proper motions, (2) the edge of M31's stellar halo, and (3) globular clusters (GCs) in the Virgo cluster of galaxies. The three science cases are about the dark matter content, accretion history, and chemical enrichment history of Local Volume galaxies. The MW science case involves using 6D stellar kinematics to study its accretion history and dark matter content. Proper motions can be measured for faint stars in the remote halo of the MW using multi-epoch Roman Telescope images or by combining astrometry from single-epoch Roman Telescope images with earlier epoch astrometry from Gaia and HST. This could extend the domain of precise astrometry by 2 mag compared to what Gaia alone is capable of. These proper motion measurements will be supplemented by radial velocities (and chemical abundances) from ground based spectroscopy. The M31 case involves mapping its stellar halo out to r ~ 300 kpc and characterizing the "edge" of the halo at the splashback radius. The Roman Telescope's wide field of view and point source depth makes this possible. The Virgo cluster science case involves the identification and study of GCs. Most of these GCs are satellites of Virgo cluster galaxies whose dynamics and chemical abundances shed light on the formation history of their host galaxies. Some of the GCss are intracluster GCs that have been stripped from their original host galaxies. |
