Limits on Collisional Dark Matter from Elliptical Galaxies in Clusters
Limits on Collisional Dark Matter from Elliptical Galaxies in Clusters
复制标题
星团中椭圆星系碰撞暗物质的限制
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
J. Ostriker
中科院分区：
文献类型：
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作者：
O. Gnedin;J. Ostriker
如果暗物质是自作用的，星系团中星系的动力学演化将被改变。热星团晕的热传导会导致相对较冷的星系晕蒸发。当恒星重新调整到暗物质的损失时，恒星的分布将绝热地扩大，从而减少速度色散，增加半光半径。根据目前的观测结果，如果暗物质含量在该半径范围内占总暗物质含量的25%-50%，则星系团中的椭圆星系将偏离观测散射以外的基面关系。要求他们的光晕持续哈勃时间似乎只排除了暗物质截面的范围，0.3cm2p/mp104cm2g-1，被认为是减少中央光晕尖端的最佳，除非≲σ<；15%。如果允许截面随暗物质粒子的相对速度σ∝v-2δ变化，则在低速弥散的矮小星系中会出现一个新的暗物质蒸发问题。只有当δ<；1.1或δ>；1.8时，星系团中的大星系和局部群中的矮星系的光晕都能存活下来。在任何一种情况下，中心密度尖点的问题仍然存在。
The dynamical evolution of galaxies in clusters would be modified if dark matter were self-interacting. Heat conduction from the hot cluster halo would lead to evaporation of the relatively cooler galactic halos. The stellar distribution would adiabatically expand as it readjusted to the loss of dark matter, reducing the velocity dispersion and increasing the half-light radius. If the dark matter content within that radius was fdm = 25%-50% of the total, as indicated by current observations, the elliptical galaxies in clusters would be offset from the fundamental plane relation beyond observational scatter. The requirement that their halos survive for a Hubble time appears to exclude just that range of the dark matter cross section, 0.3 ≲ σp/mp ≲ 104 cm2 g-1, thought to be optimal for reducing central halo cusps, unless fdm < 15%. If the cross section is allowed to vary with the relative velocity of dark matter particles, σ ∝ v-2δ, a new problem of evaporation of dark matter arises in dwarf galaxies with low velocity dispersion. The halos of large galaxies in clusters and dwarf galaxies in the Local Group can both survive only if δ < 1.1 or δ > 1.8. In either case, the problem of central density cusps remains.