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arXiv 2012.15050hep-ph
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自相互作用暗物质晕和间接探测约束中黑洞附近的密度尖峰

Density spikes near black holes in self-interacting dark matter halos and indirect detection constraints

Gerardo Alvarez, Hai-Bo Yu

摘要:

自相互作用暗物质(SIDM)自然会产生一个核心的等温密度分布,这是在许多矮星系的观测青睐。暗物质分布在一个等温晕中的中心黑洞的存在下,发展出一个密度尖峰与$r^{-7/4}$的幂律,这是浅于$r^{-7/3}$预期的无碰撞暗物质(CDM)。因此,在SIDM中,可以放松对来自密度尖峰的暗物质湮灭的间接检测约束。以银河系中密度最大的卫星星系天龙座为例,推导了SIDM和CDM晕的湮灭截面和黑洞质量的上限。对于前一种情况,即使暗物质是由热遗迹组成的,天龙座也可能拥有一个中等质量的黑洞。我们进一步探讨了来自银河系和M87的约束,其中主机的超大质量黑洞,并显示湮灭截面的上限显着削弱SIDM。我们的研究结果还表明,事件视界望远镜可以提供一个独特的测试SIDM尖峰。

英文摘要:

Self-interacting dark matter (SIDM) naturally gives rise to a cored isothermal density profile, which is favored in observations of many dwarf galaxies. The dark matter distribution in the presence of a central black hole in an isothermal halo develops a density spike with a power law of $r^{-7/4}$, which is shallower than $r^{-7/3}$ as expected for collisionless dark matter (CDM). Thus, indirect detection constraints on dark matter annihilations from the density spike could be relaxed in SIDM. Taking the most dense satellite galaxy of the Milky Way Draco as an example, we derive upper limits on the annihilation cross section and the black hole mass for both SIDM and CDM halos. For the former case, Draco could host an intermediate mass black hole even if dark matter is composed of thermal relics. We further explore the constraints from the Milky Way and M87, which host supermassive black holes, and show the upper limits on the annihilation cross section are significantly weakened in SIDM. Our results also indicate that the Event Horizon Telescope could provide a unique test of SIDM spikes.

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