EDP Sciences
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Volume 367, Number 1, February III 2001
Page(s) 27 - 32
Section Cosmology
DOI http://dx.doi.org/10.1051/0004-6361:20000357

A&A 367, 27-32 (2001)
DOI: 10.1051/0004-6361:20000357

The mass of a halo

M. White

Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
    e-mail: mwhite@cfa.harvard.edu

(Received 1 September 2000 / Accepted 17 November 2000 )

We discuss the different definitions of the mass of a halo in common use and how one may convert between them. Using N-body simulations we show that mass estimates based on spherical averages are much more tightly correlated with each other than with masses based on the number of particles in a halo. The mass functions pertaining to some different mass definitions are estimated and compared to the "universal form"of Jenkins et al. (2000). Using a different simulation pipeline and a different cosmological model we show that the mass function is well fit by the Jenkins et al. (2000) fitting function, strengthening the claim to universality made by those authors. We show that care must be taken to match the definitions of mass when using large N-body simulations to bootstrap scaling relations from smaller hydrodynamical runs to avoid observationally significant bias in the predictions for abundances of objects.

Key words: methods: N-body simulations

© ESO 2001