# Fossil stellar streams and their globular cluster populations in the E-MOSAICS simulations

Hughes, ME, Pfeffer, J, Martig, M, Bastian, N, Crain, RA, Kruijssen, JMD and Reina-Campos, M (2018) Fossil stellar streams and their globular cluster populations in the E-MOSAICS simulations. Monthly Notices of the Royal Astronomical Society, 482 (2). pp. 2795-2806. ISSN 0035-8711

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## 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 characterise. 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 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 which 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 $9.3 \pm 1.8 Gyr$.

Item Type: Article This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved astro-ph.GA; astro-ph.GA; astro-ph.SR Q Science > QB AstronomyQ Science > QC Physics Astrophysics Research Institute Oxford University Press Author 16 Nov 2018 11:43 17 Nov 2018 19:15 10.1093/mnras/sty2889 https://researchonline.ljmu.ac.uk/id/eprint/9665