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Convergence of galaxy properties with merger tree temporal resolution

Benson, Andrew J. and Borgani, Stefano and De Lucia, Gabriella and Boylan-Kolchin, Michael and Monaco, Pierluigi (2012) Convergence of galaxy properties with merger tree temporal resolution. Monthly Notices of the Royal Astronomical Society, 419 (4). pp. 3590-3603. ISSN 0035-8711. doi:10.1111/j.1365-2966.2011.20002.x.

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Dark matter halo merger trees are now routinely extracted from cosmological simulations of structure formation. These trees are frequently used as inputs to semi-analytic models of galaxy formation to provide the backbone within which galaxy formation takes place. By necessity, these merger trees are constructed from a finite set of discrete ‘snapshots’ of the N-body simulation and so have a limited temporal resolution. To date, there has been little consideration of how this temporal resolution affects the properties of galaxies formed within these trees. In particular, the question of how many snapshots are needed to achieve convergence in galaxy properties has not be answered. Therefore, we study the convergence in the stellar and total baryonic masses of galaxies, distribution of merger times, stellar mass functions and star formation rates in the Galacticus model of galaxy formation as a function of the number of ‘snapshot’ times used to represent dark matter halo merger trees. When utilizing snapshots between z= 20 and 0, we find that at least 128 snapshots are required to achieve convergence to within 5 per cent for galaxy masses, while 64 snapshots give convergence only to within 10 per cent for high-mass haloes. This convergence is obtained for mean quantities averaged over large samples of galaxies – significant variance for individual galaxies remains even when using very large numbers of snapshots. We find only weak dependence of the rate of convergence on the distribution of snapshots in time – snapshots spaced uniformly in the expansion factor, uniformly in the logarithm of expansion factor or uniformly in the logarithm of critical overdensity for collapse work equally well in almost all cases. We provide input parameters to Galacticus which allow this type of convergence study to be tuned to other simulations and to be carried out for other galaxy properties.

Item Type:Article
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URLURL TypeDescription
Benson, Andrew J.0000-0001-5501-6008
Boylan-Kolchin, Michael0000-0002-9604-343X
Additional Information:© 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS. Accepted 2011 October 12. Received 2011 October 8; in original form 2011 July 20. Article first published online: 21 Nov. 2011. AJB acknowledges the support of the Gordon & Betty Moore Foundation. SB has been partially supported by the PD51 INFN grant and by the PRIN-INAF grant ‘Towards an Italian Network for Computational Cosmology’ and acknowledges partial support by the European Commissions FP7 Marie Curie Initial Training Network CosmoComp (PITN-GA-2009-238356). GDL acknowledges financial support from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 202781. MB-K acknowledges support from the Southern California Center for Galaxy Evolution, a multicampus research programme funded by the University of California Office of Research. We thank the KITP, Santa Barbara, where this work was begun, for their hospitality. This work made extensive use of Amazon’s Elastic Compute Cloud through a generous grant from the Amazon in Education programme.
Group:Moore Center for Theoretical Cosmology and Physics
Funding AgencyGrant Number
Gordon & Betty Moore FoundationUNSPECIFIED
Istituto Nazionale di Fisica Nucleare (INFN)PD51
Marie Curie FellowshipPITN-GA-2009-238356
European Research Council (ERC)202781
Southern California Center for Galaxy EvolutionUNSPECIFIED
University of CaliforniaUNSPECIFIED
Amazon in Education ProgrammeUNSPECIFIED
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Subject Keywords:methods: numerical galaxies: formation galaxies: general cosmology: theory dark matter
Issue or Number:4
Record Number:CaltechAUTHORS:20120316-152525983
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Official Citation:Benson, A. J., Borgani, S., De Lucia, G., Boylan-Kolchin, M. and Monaco, P. (2012), Convergence of galaxy properties with merger tree temporal resolution. Monthly Notices of the Royal Astronomical Society, 419: 3590–3603. doi: 10.1111/j.1365-2966.2011.20002.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29756
Deposited By: Ruth Sustaita
Deposited On:16 Mar 2012 23:14
Last Modified:09 Nov 2021 19:29

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