Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation
Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation
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从 Vlasov-Einstein 方程导出的暗物质相空间密度和 Jeans 尺度的演化
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
J. Pacheco
中科院分区：
文献类型：
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作者：
O. F. Piattella;D. Rodrigues;J. Fabris;J. Pacheco
我们讨论了在平坦的弗里德曼宇宙中无碰撞暗物质粒子的Vlasov-Einstein方程的解。我们表明，在与原始等离子体解耦后，暗物质相空间密度指标Q在宇宙膨胀期间保持恒定，在结构形成之前。这个众所周知的结果对于非相对论性粒子是有效的，并且不像从Vlasov-Poisson系统得到的解那样“依赖于观察者”。在线性体系中，包含速度色散效应允许将无碰撞物质的物理Jeans长度定义为原始相空间密度指标的函数：\lambda ＿J = (5 \pi /G)^(1/2)Q^(-1/3) \rho ＿dm^（-1/6）。由于自由流，在物质-辐射相等时，运动的琼斯波数比运动的波数小2-3倍，导致密度波动功率谱在最低尺度上被截断。我们将讨论这两种音阶之间的物理差异。对于质量等于200 GeV的暗物质粒子，导出的Jeans质量为4.3 x 10^（-6）太阳质量。
We discuss solutions of Vlasov-Einstein equation for collisionless dark matter particles in the context of a flat Friedmann universe. We show that, after decoupling from the primordial plasma, the dark matter phase-space density indicator Q remains constant during the expansion of the universe, prior to structure formation. This well known result is valid for non-relativistic particles and is not "observer dependent" as in solutions derived from the Vlasov-Poisson system. In the linear regime, the inclusion of velocity dispersion effects permits to define a physical Jeans length for collisionless matter as function of the primordial phase-space density indicator: \lambda_J = (5\pi/G)^(1/2)Q^(-1/3)\rho_dm^(-1/6). The comoving Jeans wavenumber at matter-radiation equality is smaller by a factor of 2-3 than the comoving wavenumber due to free-streaming, contributing to the cut-off of the density fluctuation power spectrum at the lowest scales. We discuss the physical differences between these two scales. For dark matter particles of mass equal to 200 GeV, the derived Jeans mass is 4.3 x 10^(-6) solar masses.
影响因子：
5.4
作者：
Bechtle, Philip;Bringmann, Torsten;Wienemann, Peter
通讯作者：
Wienemann, Peter