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arXiv 1004.1908astro-ph.COgr-qchep-phhep-th
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从理论和观测得到的暗物质粒子的质量

The mass of the dark matter particle from theory and observations

H. J. de Vega, P. Salucci, N. G. Sanchez

备注：
17 pages, 15 figures, improved and expanded version to appear in New Astronomy
发表信息：
New Astronomy, 17, 653 -666 (2012)
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摘要：

我们将观测到的星系的核心密度和半径的性质与理论上的线性演化的密度波动计算的第一性原理，因为通货膨胀的结束，直到今天。根据宇宙学参数计算了晕半径r_0。理论密度分布rho（r）/rho（0）具有作为r/r_0的函数的通用形状，其再现了观测结果。我们表明，玻尔兹曼-弗拉索夫方程的线性近似是有效的非常大的星系，并正确地提供普遍的量是共同的所有星系，作为表面密度和密度分布。通过将理论计算的面密度与观测值相匹配，我们得到（i）在MD时代相空间密度的减小（ii）暗物质粒子的质量变为1 ~ 2 keV，退耦温度T_d变为100 GeV以上（iii）核与尖点的区别：keV的暗物质粒子产生核心密度分布，而弱相互作用粒子（m \sim 100 GeV，T_d \sim 5 GeV）产生约0.003 pc尺度的尖点密度分布。这些结果与粒子模型无关，并且与暗物质粒子的统计数据变化很小。在大星系（r_0和M_{gal}都很大）的极限情况下，非普适的星系量（需要包括合并和重子等非线性效应）在线性近似中得到了晕半径r_0、星系质量M_{gal}、晕中心密度rho_{0}和速度色散sqrt{ \bar {v^2}_{halo}}的一阶因子。这显示了线性近似方案的力量：虽然它不能捕获结构形成的全部内容，但它正确地提供了普遍的量，以及主要的非普遍的星系性质。

英文摘要：

We combine observed properties of galaxies as the core density and radius with the theoretical linear evolution of density fluctuations computed from first principles since the end of inflation till today. The halo radius r_0 is computed in terms of cosmological parameters. The theoretical density profiles rho(r)/rho(0) have an universal shape as a function of r/r_0 which reproduces the observations. We show that the linear approximation to the Boltzmann-Vlasov equation is valid for very large galaxies and correctly provides universal quantities which are common to all galaxies, as the surface density and density profile. By matching the theoretically computed surface density to its observed value we obtain (i) the decreasing of the phase-space density during the MD era (ii) the mass of the dark matter particle which turns to be between 1 and 2 keV and the decoupling temperature T_d which turns to be above 100 GeV (iii) the core vs. cusp discrimination: keV dark matter particles produce cored density profiles while wimps (m \sim 100 GeV, T_d \sim 5 GeV) produce cusped profiles at scales about 0.003 pc. These results are independent of the particle model and vary very little with the statistics of the dark matter particle. Non-universal galaxy quantities (which need to include non-linear effects as mergers and baryons) are reproduced in the linear approximation up to a factor of order one for the halo radius r_0, galaxy mass M_{gal}, halo central density rho_{0} and velocity dispersion sqrt{\bar {v^2}_{halo}} in the limiting case of large galaxies (both r_0 and M_{gal} large). This shows the power of the linear approximation scheme: although it cannot capture the whole content of the structure formation, it correctly provides universal quantities which as well as the main non-universal galaxy properties.

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