How well do we know the Halo Mass Function?

18 November 2013

The halo mass function describes the abundance of collapsed dark matter objects of a given mass, and can be used in observational tests to constrain cosmological parameters, and in theoretical models to predict galaxy clustering and even basic galaxy properties.

In their recent Letter in the Monthly Notices of the Royal Astronomical Society, CAASTRO PhD student Steven Murray, and his supervisors CAASTRO Associate Investigator Chris Power and Aaron Robotham present the halo mass function for the recently released Planck1 cosmology and compare it to predictions from previous WMAP results, focusing on the inherent uncertainty.

They conclude that the predicted mass function for PLANCK1 is consistent with previous results within the quoted uncertainties of the cosmologies. They also derive a rule-of-thumb measurement of uncertainty in the halo mass function for each cosmological data-set considered, which is important for robust model-testing with observed data. Finally they show that for the tightly constrained parameters of PLANCK1, the uncertainty due to choice of parameterisation of the mass function is similar to the cosmological uncertainty, which encourages the effort to provide more accurate theoretical mass functions for precision cosmology.

by S. Murray

Publication details:

S. G. Murray, C. Power, A. S. G. Robotham in MNRAS Letters 434 (2013) "How well do we know the Halo Mass Function?"