Mass Function Predictions Beyond LCDM

May, 2010
19 pages
Published in:
  • Astrophys.J. 732 (2011) 122
e-Print:
Report number:
  • LA-UR-09-04193

Citations per year

2009201320172021202405101520
Abstract: (arXiv)
The mass distribution of halos, as specified by the halo mass function, is a key input for several cosmological probes. The sizes of NN-body simulations are now such that, for the most part, results need no longer be statistics-limited, but are still subject to various systematic uncertainties. We investigate and discuss some of the reasons for these differences. Quantifying error sources and compensating for them as appropriate, we carry out a high-statistics study of dark matter halos from 67 NN-body simulations to investigate the mass function and its evolution for a reference Λ\LambdaCDM cosmology and for a set of wwCDM cosmologies. For the reference Λ\LambdaCDM cosmology (close to WMAP5), we quantify the breaking of universality in the form of the mass function as a function of redshift, finding an evolution of as much as 10% away from the universal form between redshifts z=0z=0 and z=2z=2. For cosmologies very close to this reference we provide a fitting formula to our results for the (evolving) Λ\LambdaCDM mass function over a mass range of 61011310156\cdot 10^{11}-3\cdot 10^{15} M_{\odot} to an estimated accuracy of about 2%. The set of wwCDM cosmologies is taken from the Coyote Universe simulation suite. The mass functions from this suite (which includes a Λ\LambdaCDM cosmology and others with w1w\simeq-1) are described by the fitting formula for the reference Λ\LambdaCDM case at an accuracy level of 10%, but with clear systematic deviations. We argue that, as a consequence, fitting formulae based on a universal form for the mass function may have limited utility in high precision cosmological applications.
Note:
  • 19 pages; 18 figures; accepted for publication in the ApJ