HMFcalc: An online tool for calculating halo mass functions

May 15, 2015

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. As one of the basic measures of dark matter, it is a quantity which is frequently required across a broad spectrum of theoretical and observational fields.

Given its ubiquity, it is perhaps surprising that until now, no standard software has been developed which calculates this function in a robust manner. This results in many researchers “re-inventing the wheel” which is prone to human error and damages reproducibility.

In their 2013 paper, CAASTR PhD student Steven Murray and Associate Investigator Chris Power, together with Aaron Robotham (all at UWA), present a new code, aimed at filling this crucial gap. The code, called hmf, is written in the popular Python language, and is well tested, well documented, numerically efficient, robust and easily extendible. Furthermore, to enhance ease-of-use across the broad user spectrum, they implemented a web-application interface to the code called HMFcalc at, so any researcher is merely a few clicks away from a mass function.

The paper also presents some toy applications using the code, develops the theoretical background of the HMF, includes a “cheat-sheet” table of HMF fits found in the literature, and includes examples of how to extend and customise the code.Publication Details:

S.G. Murray, C. Power, A.S.G. Robotham in Astronomy & Computing (2013) “HMFcalc: An online tool for calculating dark matter halo mass functions”