http://arxiv.org/abs/1801.02723
The halo mass function, encoding the comoving number density of dark matter halos of a given mass, plays a key role in understanding the formation and evolution of galaxies. As such, it is a key goal of current and future deep optical surveys to constrain the mass function down to mass scales which typically host $L_\star$ galaxies. Motivated by the proven accuracy of Press-Schechter-type mass functions, we introduce a related but purely empirical form consistent with standard formulae to better than 4\% in the medium-mass regime, $10^{10}-10^{13} h^{-1}M_\odot$. In particular, our form consists of 4 parameters, each of which has a simple interpretation, and can be directly related to parameters of the galaxy distribution, such as $L_\star$.
Using this form within a hierarchical Bayesian likelihood model, we show how individual mass-measurement errors can be successfully included in a typical analysis whilst accounting for Eddington bias. We apply our form to a question of survey design in the context of a semi-realistic data model, illustrating how it can be used to obtain optimal balance between survey depth and angular coverage for constraints on mass function parameters.
Open-source {\tt Python} and {\tt R} codes to apply our new form are provided at \url{this http URL} and \url{https://cran.r-project.org/web/packages/tggd/index.html} respectively.
S. Murray, A. Robotham and C. Power
Wed, 10 Jan 18
11/65
Comments: 23 pages, 11 figures, accepted to ApJ
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