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DARK MATTER HALOES:AN ADDITIONAL CRITERION FOR THE CHOICE OF FITTING DENSITY PROFILES

http://www.firstlight.cn2009/3/5

[作者] R. Caimmi C. Marmo

[单位] Dipartimento di Astronomia, Universita' di Padova

[摘要] Simulated dark matter haloes are tted by self-similar, universal density pro les, where the scaled parameters depend only on a scaled (truncation) radius,  = R=r0, which, in turn, is supposed to be independ…

[关键词] cosmology dark matter

Simulated dark matter haloes are tted by self-similar, universal

density pro les, 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 pro le, with regard

to a set of high-resolution simulations, where some averaging procedure on scaled

density pro les has been performed, in connection with a number of tting density

pro les. 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 pro le; 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 pro les, 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 pro les, 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.

存档附件原文地址

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 PROFILEShttp://ynufe.firstlight.cn/View.aspx?infoid=641013&cb=fanshujingxg
发布时间:2009/3/5.检索时间:2024/12/13

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