Year: 2018
Type: article
Abstract: Stellar haloes encode a fossil record of a galaxy’s accretion history, generally in the form of structures of low surface brightness, such as stellar streams. While their low surface brightness makes it challenging to determine their age, metallicity, kinematics, and spatial structure, the infalling galaxies also deposit globular clusters (GCs) in the halo, which are bright and therefore easier to observe and characterize. To understand how GCs associated with stellar streams can be used to estimate the stellar mass and the infall time of their parent galaxy, we examine a subset of 15 simulations of galaxies and their star clusters from the E-MOSAICS project. E-MOSAICS is a suite of hydrodynamical simulations incorporating a sub-grid model for GC formation and evolution. We find that more massive accreted galaxies typically contribute to younger and more metal-rich GCs. This lower age results from a more extended cluster formation history in more massive galaxies. In addition, at fixed stellar mass, galaxies that are accreted later host younger clusters, because they can continue to form GCs without being subjected to environmental influences for longer. This explains the large range of ages observed for clusters associated with the Sagittarius dwarf galaxy in the halo of the Milky Way compared to clusters that are thought to have formed in satellites accreted early in the Milky Way’s formation history. Using the ages of the GCs associated with the Sagittarius dwarf, we estimate a virial radius crossing lookback time (infall time) of |$9.3 \pm 1.8\, {\rm Gyr}$|.
Institutions: Liverpool John Moores University, Heidelberg University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Durham University, Deutsche Forschungsgemeinschaft, Universität Heidelberg, Liverpool John Moores University, International Max Planck Research School for Advanced Methods in Process and Systems Engineering, Medical Research Council, Science and Technology Facilities Council, European Research Council, Horizon 2020, H2020 European Research Council
Awards: G1062116400, Visiting Fellowships at Durham, Multi-scale Star Formation Across Nascent Galaxies, G1381339075, G144508916, Durham DiRAC-2 petascale facility, G2918681272, Using Globular Clusters as Tracers of Galaxy Formation, G432354605, G4831232377, G7165083805, G8092745986, The Virgo consortium for cosmological supercomputer simulations, Durham DiRAC-2 petascale facility support, G872726024
OpenAlex ID: W2897622427