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arXiv 1104.2334astro-ph.CO
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理论暗物质晕密度轮廓

Theoretical dark matter halo density profile

Eduard Salvador-Solé, Jordi Viñas, Alberto Manrique, Sinue Serra

摘要:

利用二次入射(SI)模型,推导了分层宇宙学中无碰撞无耗散暗物质晕的密度分布。这些新奇之处是:i)我们处理三轴维里化对象; ii)他们的种子在线性政权的峰值赋予{ \it unconvolved}球平均密度分布根据峰值形式主义; iii)考虑到初始的特殊速度;和iv)吸积晕被假定为从内到外发展,保持瞬时内部系统不变。后一种假设的有效性准确地检查比较分析预测,这样的增长与数值模拟的结果。我们表明,球平均密度轮廓的维里化对象可以推断,而不需要指定它们的形状。{ \it典型}球平均晕密度分布推断,到任意小的半径,从密度扰动的功率谱。在$Λ$ CDM宇宙学中的预测轮廓近似地由Einasto轮廓描述,这意味着它没有尖点,而是有一个核心,其中内部斜率缓慢地收敛到零。下降到百分之一的总半径,配置文件有正确的NFW和Einasto的形式,接近后者下降到一个半径约4个数量级less. the模型的内部一致性意味着,晕的密度配置文件海港没有信息,他们过去的聚集历史。这就解释了为什么大的合并不会改变SI形成的维里化天体的典型密度分布,也不会使基于这种形成的峰值形式主义失效。

英文摘要:

We derive the density profile for collisionless dissipationless dark matter haloes in hierarchical cosmologies making use of the Secondary Infall (SI) model. The novelties are: i) we deal with triaxial virialised objects; ii) their seeds in the linear regime are peaks endowed with {\it unconvolved} spherically averaged density profiles according to the peak formalism; iii) the initial peculiar velocities are taken into account; and iv) accreting haloes are assumed to develop from the inside out, keeping the instantaneous inner system unaltered. The validity of this latter assumption is accurately checked by comparing analytical predictions on such a growth with the results of numerical simulation. We show that the spherically averaged density profile of virialised objects can be inferred with no need to specify their shape. The {\it typical} spherically averaged halo density profile is inferred, down to arbitrarily small radii, from the power-spectrum of density perturbations. The predicted profile in the $Λ$CDM cosmology is approximately described by an Einasto profile, meaning that it does not have a cusp but rather a core, where the inner slope slowly converges to zero. Down to one hundredth the total radius, the profile has the right NFW and Einasto forms, being close to the latter down to a radius of about four orders of magnitude less. The inner consistency of the model implies that the density profiles of haloes harbour no information on their past aggregation history. This would explain why major mergers do not alter the typical density profile of virialised objects formed by SI and do not invalidate the peak formalism based on such a formation.

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