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arXiv 0711.3555astro-ph
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“冷却流”星系团中暗物质与重子的碰撞相互作用极限

Collisional interaction limits between dark matters and baryons in `cooling flow' clusters

Jian Hu, Yu-Qing Lou

摘要:

假设弱碰撞相互作用,以交换星系团中的暗物质和重子物质之间的动能,我们重新审视这一过程的有效性,在几个“冷却流”星系团使用现有的X射线观测和推断的上限重暗物质粒子(重)$-$质子截面$σ_{\rm xp}$。对于$σ_{\rm xp}=σ_0(V/10^3 {\rm km s^{-1}})^a$的相对碰撞速度$V-$依赖幂律形式,其中$a\leq 0$,我们推断的上限是$σ_0/m_{\rm x}\lsim 2\times10^{-25} {\rm cm}^2 {\rm GeV}^{-1}$,其中$m_{\rm x}$是质量。基于对热能平衡方程的简单稳定性分析,我们认为,在“冷流”星系团的内核区域,团内$-$重子碰撞相互作用机制不可能是稳定的团内介质(ICM)的非引力热源.

英文摘要:

Presuming weak collisional interactions to exchange the kinetic energy between dark matter and baryonic matter in a galaxy cluster, we re-examine the effectiveness of this process in several `cooling flow' galaxy clusters using available X-ray observations and infer an upper limit on the heavy dark matter particle (DMP)$-$proton cross section $σ_{\rm xp}$. With a relative collisional velocity $V-$dependent power-law form of $σ_{\rm xp}=σ_0(V/10^3 {\rm km s^{-1}})^a$ where $a\leq 0$, our inferred upper limit is $σ_0/m_{\rm x}\lsim 2\times10^{-25} {\rm cm}^2 {\rm GeV}^{-1}$ with $m_{\rm x}$ being the DMP mass. Based on a simple stability analysis of the thermal energy balance equation, we argue that the mechanism of DMP$-$baryon collisional interactions is unlikely to be a stable nongravitational heating source of intracluster medium (ICM) in inner core regions of `cooling flow' galaxy clusters.

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