The "Building Blocks" of Stellar Halos

Abstract

The stellar halos of galaxies encode their accretion histories. In particular, the median metallicity of a halo is determined primarily by the mass of the most massive accreted object. We use hydrodynamical cosmological simulations from the APOSTLE project to study the connection between the stellar mass, the metallicity distribution, and the stellar age distribution of a halo and the identity of its most massive progenitor. We find that the stellar populations in an accreted halo typically resemble the old stellar populations in a present-day dwarf galaxy with a stellar mass $\sim 0.2-0.5$ dex greater than that of the stellar halo. This suggest that had they not been accreted, the primary progenitors of stellar halos would have evolved to resemble typical nearby dwarf irregulars.

7 pages, 3 figures, published in the proceedings of "On the Origin (and Evolution) of Baryonic Galaxy Halos", Puerto Ayora, Ecuador, March 13-17 2017, Eds. Duncan A. Forbes and Ericson D. Lopez

References in corpus (7)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• The effect of photo-ionization on the cooling rates of enriched, astrophysical plasmas
• Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations
• Diverse Stellar Haloes in Nearby Milky Way-Mass Disc Galaxies
• Galaxies grow their bulges and black holes in diverse ways
• The age structure of the Milky Way's halo

Cited by in corpus (3)

• The Pristine survey VIII: The metallicity distribution function of the Milky Way halo down to the extremely metal-poor regime
• A missing outskirts problem? Comparisons between stellar halos in the Dragonfly Nearby Galaxies Survey and the TNG100 simulation
• The Escape of Globular Clusters from the Satellite Dwarf Galaxies of the Milky Way