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Galactic stellar haloes in the CDM model

Cooper, A. P. and Cole, S. and Frenk, C. S. and White, S. D. M. and Helly, J. and Benson, A. J. and De Lucia, G. and Helmi, A. and Jenkins, A. and Navarro, J. F. and Springel, V. and Wang, J. (2010) Galactic stellar haloes in the CDM model. Monthly Notices of the Royal Astronomical Society, 406 (2). pp. 744-766. ISSN 0035-8711. doi:10.1111/j.1365-2966.2010.16740.x.

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We present six simulations of galactic stellar haloes formed by the tidal disruption of accreted dwarf galaxies in a fully cosmological setting. Our model is based on the Aquarius project, a suite of high-resolution N-body simulations of individual dark matter haloes. We tag subsets of particles in these simulations with stellar populations predicted by the galform semi-analytic model. Our method self-consistently tracks the dynamical evolution and disruption of satellites from high redshift. The luminosity function (LF) and structural properties of surviving satellites, which agree well with observations, suggest that this technique is appropriate. We find that accreted stellar haloes are assembled between 1 < z < 7 from less than five significant progenitors. These progenitors are old, metal-rich satellites with stellar masses similar to the brightest Milky Way dwarf spheroidals (10^(7)–10^(8) M_⊙). In contrast to previous stellar halo simulations, we find that several of these major contributors survive as self-bound systems to the present day. Both the number of these significant progenitors and their infall times are inherently stochastic. This results in great diversity among our stellar haloes, which amplifies small differences between the formation histories of their dark halo hosts. The masses (~10^(8)–10^(9) M_⊙) and density/surface-brightness profiles of the stellar haloes (from 10 to 100 kpc) are consistent with expectations from the Milky Way and M31. Each halo has a complex structure, consisting of well-mixed components, tidal streams, shells and other subcomponents. This structure is not adequately described by smooth models. The central regions (<10 kpc) of our haloes are highly prolate (c/a ~ 0.3), although we find one example of a massive accreted thick disc. Metallicity gradients in our haloes are typically significant only where the halo is built from a small number of satellites. We contrast the ages and metallicities of halo stars with surviving satellites, finding broad agreement with recent observations.

Item Type:Article
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Benson, A. J.0000-0001-5501-6008
Springel, V.0000-0001-5976-4599
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 March 24. Received 2010 February 17; in original form 2009 October 30. Article first published online: 3 May 2010. TThe simulations for the Aquarius Project were carried out at the Leibniz Computing Centre, Garching, Germany, at the Computing Centre of the Max-Planck-Society in Garching, at the Institute for Computational Cosmology in Durham, and on the ‘STELLA’ supercomputer of the LOFAR experiment at the University of Groningen. APC is supported by an STFC postgraduate studentship, acknowledges support from the Royal Astronomical Society and Institute of Physics and thanks the KITP, Santa Barbara, for hospitality during the early stages of this work. He also thanks Annette Ferguson for helpful comments and Ben Lowing for code to calculate ellipsoidal fits to particle distributions. CSF acknowledges a Royal Society Wolfson Research Merit Award. AH acknowledges support from a VIDI grant by Netherlands Organisation for Scientific Research (NWO). AJB acknowledges the support of the Gordon & Betty Moore foundation. JW acknowledges a Royal Society Newton Fellowship. GDL acknowledges financial support from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement n. 202781. We thank the referee for their suggestions, which improved the presentation and clarity of the paper.
Group:Moore Center for Theoretical Cosmology and Physics
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)UNSPECIFIED
Royal Astronomical SocietyUNSPECIFIED
Institute of PhysicsUNSPECIFIED
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
European Research Council (ERC)202781
Subject Keywords:methods: numerical; Galaxy: halo; galaxies: dwarf; galaxies: formation; galaxies: haloes; galaxies: structure
Issue or Number:2
Record Number:CaltechAUTHORS:20100903-105537495
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Official Citation:Cooper, A. P., Cole, S., Frenk, C. S., White, S. D. M., Helly, J., Benson, A. J., De Lucia, G., Helmi, A., Jenkins, A., Navarro, J. F., Springel, V. and Wang, J. (2010), Galactic stellar haloes in the CDM model. Monthly Notices of the Royal Astronomical Society, 406: 744–766. doi: 10.1111/j.1365-2966.2010.16740.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19784
Deposited On:08 Sep 2010 15:25
Last Modified:08 Nov 2021 23:55

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