Simulated dark matter haloes are tted by self-similar, universal
density proles, where the scaled parameters depend only on a scaled (truncation)
radius, = R=r0, which, in turn, is supposed to be independent of the mass and
the formation redshift. The further assumption of a lognormal distribution (for a
selected mass bin) of the scaled radius, or concentration, in agreement with the data
from a large statistical sample of simulated haloes (Bullock et al. 2001), allows (at
least to a rst approximation) a normal or lognormal distribution for other scaled
parameters, via the same procedure which leads to the propagation of the errors.
A criterion is proposed for the choice of the best tting density prole, with regard
to a set of high-resolution simulations, where some averaging procedure on scaled
density proles has been performed, in connection with a number of tting density
proles. To this aim, a minimum value of the ratio, jxj=s = j j=s , is
required to yield the best t, where is the arithmetic mean over the whole set;
is its counterpart related to the tting density prole; s is the standard deviation
from the mean; and is a selected, scaled i.e. dimensionless parameter. The
above criterion is applied to a pair of sets each made of a dozen of high-resolution
simulations, FM01 (Fukushige and Makino 2001) and KLA01 (Klypin et al. 2001),
in connection with two currently used tting density proles, NFW (e.g. Navarro
et al. 1997) and MOA (e.g. Moore et al. 1999), where the dependence of the scaled
radius on the mass and the formation redshift may be neglected to a rst extent.
With regard to FM01 and KLA01 samples, the best ts turn out to be MOA and
NFW, respectively. In addition, the above results also hold in dealing with rms
errors derived via the propagation of the errors, with regard to the distributions
of scaled parameters. The sensitivity error of simulations is also estimated and
shown to be less than the related, standard deviation, that is a necessary condition
for detectability of accidental errors. Some features of the early evolution of dark
matter haloes, represented by tting density proles, are discussed in the limit of
the spherical top-hat model. Although the related matter distributions appear to
be poorly representative of simulated haloes, unless the (mean) peak height is an
increasing function of the mass, the results are shown to be consistent, provided
considerable acquisition of angular momentum takes place during the expansion
phase.
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原文发布时间:2009/3/5
引用本文:
R. Caimmi;C. Marmo.DARK MATTER HALOES:AN ADDITIONAL CRITERION FOR THE CHOICE OF FITTING DENSITY PROFILES.http://ynufe.firstlight.cn/View.aspx?infoid=641013&cb=fanshujingxg.
发布时间:2009/3/5.检索时间:2024/12/13