arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0705.2588astro-ph
收藏

星系团中cosmic-ray压力的Gamma-ray探测及其宇宙学意义

Gamma-ray probe of cosmic-ray pressure in galaxy clusters and cosmological implications

Shin'ichiro Ando, Daisuke Nagai

摘要:

星系团吸积和合并激波产生的宇宙射线对团内介质(ICM)产生压力,影响对星系团质量的估计。虽然ICM中存在宇宙射线离子的直接证据仍然缺乏,但它们通过与ICM核子碰撞产生的中性π介子衰变产生伽马射线辐射。我们调查的能力,伽玛射线大面积空间望远镜(GLAST)和成像大气切伦科夫望远镜(IACT)约束宇宙射线压力的贡献ICM。我们表明,GLAST可以用来放置严格的上限,几个百分点的个别附近的丰富的集群,对宇宙射线和热气体的压力比。我们进一步表明,在硬谱的情况下,通过堆叠来自已知簇的样本的信号,可以对遥远的(z <~ 0.25)簇设置严格的(<~10%)约束。GLAST的极限可以通过IACT可能提供的宇宙射线谱的约束而变得更加精确。未来对星系团的伽马射线观测可以限制宇宙射线能量密度的演化,这将对即将进行的X射线和Sunyaev-Zel'dovich效应星系团巡天的宇宙学测试产生重要影响。

英文摘要:

Cosmic rays produced in cluster accretion and merger shocks provide pressure to the intracluster medium (ICM) and affect the mass estimates of galaxy clusters. Although direct evidence for cosmic-ray ions in the ICM is still lacking, they produce gamma-ray emission through the decay of neutral pions produced in their collisions with ICM nucleons. We investigate the capability of the Gamma-ray Large Area Space Telescope (GLAST) and imaging atmospheric Cerenkov telescopes (IACTs) for constraining the cosmic-ray pressure contribution to the ICM. We show that GLAST can be used to place stringent upper limits, a few per cent for individual nearby rich clusters, on the ratio of pressures of the cosmic rays and thermal gas. We further show that it is possible to place tight (<~10%) constraints for distant (z <~ 0.25) clusters in the case of hard spectrum, by stacking signals from samples of known clusters. The GLAST limits could be made more precise with the constraint on the cosmic-ray spectrum potentially provided by IACTs. Future gamma-ray observations of clusters can constrain the evolution of cosmic-ray energy density, which would have important implications for cosmological tests with upcoming X-ray and Sunyaev-Zel'dovich effect cluster surveys.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑