The Parameter Space of Galaxy Formation
Bower, R.G.; Vernon, I.; Goldstein, M.; Benson, A.J.; Lacey, C.G.; Baugh, C.M.; Cole, S.; Frenk, C.S.
Professor Ian Vernon firstname.lastname@example.org
Professor Cedric Lacey email@example.com
Professor Carlton Baugh firstname.lastname@example.org
Professor Shaun Cole email@example.com
Director of the Institute for Computational Cosmology
Professor Carlos Frenk firstname.lastname@example.org
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.
Bower, R., Vernon, I., Goldstein, M., Benson, A., Lacey, C., Baugh, C., …Frenk, C. (2010). The Parameter Space of Galaxy Formation. Monthly Notices of the Royal Astronomical Society, 407(4), 2017-2045. https://doi.org/10.1111/j.1365-2966.2010.16991.x
|Journal Article Type||Article|
|Publication Date||Oct 1, 2010|
|Deposit Date||Mar 21, 2011|
|Publicly Available Date||Nov 20, 2013|
|Journal||Monthly Notices of the Royal Astronomical Society|
|Publisher||Royal Astronomical Society|
|Peer Reviewed||Peer Reviewed|
|Keywords||Galaxies: formation, Galaxies: luminosity function, mass function.|
|Related Public URLs||http://ukads.nottingham.ac.uk/abs/2010MNRAS.407.2017B|
Published Journal Article
This article has been published in the Monthly Notices of the Royal Astronomical Society ©: 2010 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved.
You might also like
A sparse regression approach for populating dark matter haloes and subhaloes with galaxies
The importance of black hole repositioning for galaxy formation simulations