A Physical Bias in Cosmological Simulations

Дата и время публикации : 2004-09-22T01:37:50Z

Авторы публикации и институты :
Weike Xiao
Zhengfan Sun
Heng Hao

Оригинал статьи :http://arxiv.org/abs/astro-ph/0409524v2

Скачать pdf : http://arxiv.org/pdf/astro-ph/0409524v2

Ссылка на журнал-издание: Astrophys.J.617:L103-L106,2004
Коментарии к статье: 4 pages,no figures. Submitted to ApJl
Первичная категория: astro-ph

Все категории : astro-ph

Краткий обзор статьи: Numerical simulation plays an important role in the study of structure formation of the universe. However, the mass resolution in current simulations is still poor. Due to technical difficulties, it is necessary to use both greatly reduced number density of particles and greatly raised unit particle mass. Consequently, the particle masses used in cosmological simulations are about $10^{70}$ times larger than the $Gev$ candidates in particle physics. This is a huge physical bias that cannot be neglected when interpreting the results of the simulations. Here we discuss how such a bias affects Cold Dark Matter (CDM) cosmological simulations. We find that the small scale properties of the CDM particle system are changed in two aspects. 1) An upper limit is imposed on the spatial resolution of the simulation results. 2) Most importantly, an unexpected short mean free path is produced, and the corresponding two body scattering cross section is close to the value expected in the Self-Interaction Dark Matter(SIDM) model. Since the mean free path of real CDM particle systems is much longer than that in the simulations, our results imply 1) that there is probably no ‘cusp problem’ in real CDM halos, and 2) that a much longer time is needed to form new virialized halos in real CDM particle systems than in the simulations. This last result can help us understand the ‘substructure problem’. Our discussion can also explain why the massive halos in the simulations may have smaller concentration coefficients.

Category: Physics