Journal Article

Bayesian inference of galaxy formation from the <i>K</i>-band luminosity function of galaxies: tensions between theory and observation

Yu Lu, H. J. Mo, Neal Katz and Martin D. Weinberg

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 421, issue 2, pages 1779-1796
Published in print April 2012 | ISSN: 0035-8711
Published online March 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20435.x
Bayesian inference of galaxy formation from the K-band luminosity function of galaxies: tensions between theory and observation

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We conduct Bayesian model inferences from the observed K-band luminosity function of galaxies in the local Universe, using the semi-analytic model (SAM) of galaxy formation introduced in Lu et al. The prior distributions for the 14 free parameters include a large range of possible models. We find that some of the free parameters, e.g. the characteristic scales for quenching star formation in both high-mass and low-mass haloes, are already tightly constrained by the single data set. The posterior distribution includes the model parameters adopted in other SAMs. By marginalizing over the posterior distribution, we make predictions that include the full inferential uncertainties for the colour–magnitude relation, the Tully–Fisher relation, the conditional stellar mass function of galaxies in haloes of different masses, the H i mass function, the redshift evolution of the stellar mass function of galaxies and the global star formation history. Using posterior predictive checking with the available observational results, we find that the model family (i) predicts a Tully–Fisher relation that is curved; (ii) significantly overpredicts the satellite fraction; (iii) vastly overpredicts the H i mass function; (iv) predicts high-z stellar mass functions that have too many low-mass galaxies and too few high-mass ones and (v) predicts a redshift evolution of the stellar mass density and the star formation history that are in moderate disagreement. These results suggest that some important processes are still missing in the current model family, and we discuss a number of possible solutions to solve the discrepancies, such as interactions between galaxies and dark matter haloes, tidal stripping, the bimodal accretion of gas, preheating and a redshift-dependent initial mass function.

Keywords: methods: numerical; methods: statistical; galaxies: evolution; galaxies: formation; galaxies: luminosity function, mass function

Journal Article.  12754 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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