Understanding the effects of Mergers on Milky Way-mass galaxies: Linking the galactic accretion history with the extra-galactic one.
Richard D' Souza (Specola Vaticana)
Tuesday 21/03/2023 @ 14:00, Sala IV piano Battiferro - Presenza + remoto
Identifying significant past accretion events is essential to understand how mergers affect the physical properties of Milky Way (MW)-mass galaxies. Gaia in combination with ground-based spectroscopic surveys have revolutionized our understanding of the MW’s past mergers. But it is important to put the accretion history of MW in the context of other well-studied galaxies of similar mass in the Local Volume whose haloes stars can be resolved using existing space-based or 8-meter class telescopes. I will discuss how it is possible to constrain the mass and the time of accretion of a MW-mass galaxy’s most significant past merger from resolved studies of the RGB and AGB stars in its stellar halo, demonstrating with the concrete cases of M31 and M81. I will discuss how these significant mergers contribute to the heating of the galactic disk and to the accretion of smaller satellite galaxies, but do not contribute substantially to the building of their galactic bulges. Finally, I will discuss how the constraints of the significant merger of MW-mass galaxies as revealed by their stellar haloes can be used to interpret the other known tracers of its accretion history including its globular clusters, its stellar streams and its existing dwarf satellites.