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The parameter space of galaxy formation

Bower, R. G. and Vernon, I. and Goldstein, M. and Benson, A. J. and Lacey, C. G. and Baugh, C. M. and Cole, S. and Frenk, C. S. (2010) The parameter space of galaxy formation. Monthly Notices of the Royal Astronomical Society, 407 (4). pp. 2017-2045. ISSN 0035-8711.

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Semi-analytic models are a powerful tool for studying the formation of galaxies. However, these models inevitably involve a significant number of poorly constrained parameters that must be adjusted to provide an acceptable match to the observed Universe. In this paper, we set out to quantify the degree to which observational data sets can constrain the model parameters. By revealing degeneracies in the parameter space we can hope to better understand the key physical processes probed by the data. We use novel mathematical techniques to explore the parameter space of the galform semi-analytic model. We base our investigation on the Bower et al. version of galform, adopting the same methodology of selecting model parameters based on an acceptable match to the local bJ and K luminosity functions. Since the galform model is inherently approximate, we explicitly include a model discrepancy term when deciding if a match is acceptable or not. The model contains 16 parameters that are poorly constrained by our prior understanding of the galaxy formation processes and that can plausibly be adjusted between reasonable limits. We investigate this parameter space using the Model Emulator technique, constructing a Bayesian approximation to the galform model that can be rapidly evaluated at any point in parameter space. The emulator returns both an expectation for the galform model and an uncertainty which allows us to eliminate regions of parameter space in which it is implausible that a galform run would match the luminosity function data. By combining successive waves of emulation, we show that only 0.26 per cent of the initial volume is of interest for further exploration. However, within this region we show that the Bower et al. model is only one choice from an extended subspace of model parameters that can provide equally acceptable fits to the luminosity function data. We explore the geometry of this region and begin to explore the physical connections between parameters that are exposed by this analysis. We also consider the impact of adding additional observational data to further constrain the parameter space. We see that the known tensions existing in the Bower et al. model lead to a further reduction in the successful parameter space.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle Paper
Bower, R. G.0000-0002-5215-6010
Benson, A. J.0000-0001-5501-6008
Lacey, C. G.0000-0001-9016-5332
Baugh, C. M.0000-0002-9935-9755
Frenk, C. S.0000-0002-2338-716X
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 May 10. Received 2010 April 5; in original form 2009 December 10. RGB acknowledges the support of a Durham-University Christopherson-Knott Fellowship. IRV and MG acknowledge the support of the Basic Technology initiative as part of the Managing Uncertainty for Complex Models project. IRV acknowledges the support of an EPSRC mobility fellowship. AJB acknowledges the support of the Gordon & Betty Moore Foundation. CGL acknowledges support from the STFC rolling grant to the ICC.
Group:Moore Center for Theoretical Cosmology and Physics
Funding AgencyGrant Number
Durham-University Christopherson-Knott FellowshipUNSPECIFIED
Basic Technology initiativeUNSPECIFIED
Engineering and Physical Sciences Research Council (EPSRC)UNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Subject Keywords:galaxies: formation; galaxies: luminosity function; mass function
Issue or Number:4
Record Number:CaltechAUTHORS:20101022-082310974
Persistent URL:
Official Citation:Bower, R. G., Vernon, I., Goldstein, M., Benson, A. J., Lacey, C. G., Baugh, C. M., Cole, S. and Frenk, C. S. (2010), The parameter space of galaxy formation. Monthly Notices of the Royal Astronomical Society, 407: 2017–2045. doi: 10.1111/j.1365-2966.2010.16991.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20474
Deposited By: Tony Diaz
Deposited On:30 Nov 2010 22:24
Last Modified:10 Feb 2021 23:27

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