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The origin of the 'blue tilt' of globular cluster populations in the E-MOSAICS simulations

Usher, CG, Pfeffer, J, Bastian, N, Kruijssen, JMD, Crain, RA and Reina-Campos, M (2018) The origin of the 'blue tilt' of globular cluster populations in the E-MOSAICS simulations. Monthly Notices of the Royal Astronomical Society. ISSN 0035-8711

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The metal-poor sub-population of globular cluster (GC) systems exhibits a correlation between the GC average colour and luminosity, especially in those systems associated with massive elliptical galaxies. More luminous (more massive) GCs are typically redder and hence more metal-rich. This 'blue tilt' is often interpreted as a mass-metallicity relation stemming from GC self-enrichment, whereby more massive GCs retain a greater fraction of the enriched gas ejected by their evolving stars, fostering the formation of more metal-rich secondary generations. We examine the E-MOSAICS simulations of the formation and evolution of galaxies and their GC populations, and find that their GCs exhibit a colour-luminosity relation similar to that observed in local galaxies, without the need to invoke mass-dependent self-enrichment. We find that the blue tilt is most appropriately interpreted as a dearth of massive, metal-poor GCs: the formation of massive GCs requires high interstellar gas surface densities, conditions that are most commonly fostered by the most massive, and hence most metal rich, galaxies, at the peak epoch of GC formation. The blue tilt is therefore a consequence of the intimate coupling between the small-scale physics of GC formation and the evolving properties of interstellar gas hosted by hierarchically-assembling galaxies.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record Christopher Usher, Joel Pfeffer, Nate Bastian, J M Diederik Kruijssen, Robert A Crain, Marta Reina-Campos; The origin of the ‘blue tilt’ of globular cluster populations in the E-MOSAICS simulations, Monthly Notices of the Royal Astronomical Society, , sty1895, is available online at: https://doi.org/10.1093/mnras/sty1895
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 26 Jul 2018 10:41
Last Modified: 01 Aug 2018 08:10
URI: http://researchonline.ljmu.ac.uk/id/eprint/9027

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