arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1002.3660astro-ph.CO
收藏

标准宇宙学模型中的晕和星系:Bolshoi模拟的结果

Halos and galaxies in the standard cosmological model: results from the Bolshoi simulation

A. Klypin, S. Trujillo-Gomez, J. Primack

摘要:

我们提出了新的Bolshoi N体宇宙学LCDM模拟的第一个结果,该模拟使用了当前观测所支持的宇宙学参数。Bolshoi的模拟是在一个250 Mpc的体积中进行的,使用了80亿个粒子,其质量和力的分辨率足以跟踪下晕,直到Vcirc= 50 km/ s的圆速度的完整性极限。使用出色的统计晕和subhalos(10 M在每一个时刻和50 M的整个历史),我们提出了准确的近似统计,如晕质量函数,浓度为不同的晕和subhalos,丰富的晕作为其圆速度的函数,丰富和空间分布的subhalos。我们发现,在高红移的浓度下降到最低值约3.8,然后略有上升,为更高的值晕质量。我们发现,虽然谢斯-托门近似的质量函数的晕发现的球形超密度是准确的,在低红移,它过度预测的丰富晕的数量级接近z=10。我们发现,subhalo的数量与宿主晕的圆速度为Vhost**0.5的比例,并且subhalo具有与暗物质粒子几乎相同的径向分布,半径为宿主晕维里半径的0.3-2倍。晕下速度函数n(>V)表现为V**(-3)。我们给出了不同质量和红移的这种关系的归一化。最后,我们用丰度匹配方法将r波段光度作为晕Vcirc的函数分配给了暗物质晕,发现在50- 200 km/s范围内,光度-速度关系与Tully-Fisher关系非常吻合。

英文摘要:

We present the first results from the new Bolshoi N-body cosmological LCDM simulation that uses cosmological parameters favored by current observations. The Bolshoi simulation was done in a volume 250Mpc on a side using 8billion particles with mass and force resolution adequate to follow subhalos down to a completeness limit of Vcirc=50km/ s circular velocity. Using excellent statistics of halos and subhalos (10M at every moment and 50M over the whole history) we present accurate approximations for statistics such as the halo mass function, the concentrations for distinct halos and subhalos, abundance of halos as function of their circular velocity, the abundance and the spatial distribution of subhalos. We find that at high redshifts the concentration falls to a minimum of about 3.8 and then rises slightly for higher values of halo mass. We find that while the Sheth-Tormen approximation for the mass function of halos found by spherical overdensity is accurate at low redshifts, it over-predicts the abundance of halos by nearly an order of magnitude by z=10. We find that the number of subhalos scales with the circular velocity of the host halo as Vhost**0.5, and that subhalos have nearly the same radial distribution as dark matter particles at radii 0.3-2 times the host halo virial radius. The subhalo velocity function n(>V) behaves as V**(-3). We give normalization of this relation for different masses and redshifts. Finally, we use an abundance-matching procedure to assign r-band luminosities to dark matter halos as a function of halo Vcirc, and find that the luminosity-velocity relation is in remarkably good agreement with the observed Tully-Fisher relation for galaxies in the range 50-200km/s.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑