Deciphering the accretion history of galaxies: insights from stellar halos
Abstract
During the last decade, significant progress has been made to resolve the halos of nearby galaxies. In this proceeding we mostly focus on the results from the GHOSTS survey, an HST imaging survey of nearby galaxies. Stellar halos show a large diversity in their properties for Milky Way-like galaxies that are alike in terms of total luminosity and stellar mass. Another important result from this survey is the discovery of a stellar halo mass--metallicity relation, which allows to constrain the mass and metallicity of the most massive accreted satellite. We also discuss the results from the stellar halos of the Auriga simulations, a suite of forty cosmological magneto-hydrodynamical zoom-in simulations of Milky Way-mass galaxies. A comparison between the results from the Auriga simulations with those obtained from observations of nearby galaxies shows a good agreement. We discuss observational signatures of stellar halos that allow us to decode the accretion and merger history of observed galaxies. In particular, the stellar mass and metallicity of the halos at 30 kpc reflect the properties of the most massive accreted satellite, and strong metallicity gradients are found when the stellar halo is built from few (one to four) significant progenitors.
- Publication:
-
Boletin de la Asociacion Argentina de Astronomia La Plata Argentina
- Pub Date:
- August 2020
- Bibcode:
- 2020BAAA...61C..28M
- Keywords:
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- galaxies: halos;
- galaxies: stellar content;
- galaxies: structure;
- galaxies: evolution