Entropy at the Outskirts of Galaxy Clusters as Implications for Cosmological Cosmic-Ray Acceleration
Entropy at the Outskirts of Galaxy Clusters as Implications for Cosmological Cosmic-Ray Acceleration
复制标题
星系团外围的熵对宇宙学宇宙射线加速的影响
DOI：
10.1088/2041-8205/767/1/l4
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Yutaka Fujita
中科院分区：
文献类型：
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作者：
M. Garcia Perez;A. Gonzalez-Arroyo;M. Okawa;Yutaka Fujita
近年来，星系团外围的气体熵引起了人们的广泛关注。我们建议可以使用熵分布来研究星系团周围的宇宙射线（CR）加速。如果CRs在团簇形成时被有效地加速，则下落气体的动能被加速消耗，并且气体熵应该减小。结果，熵分布在外围变得平坦。如果加速度不是有效的，熵应该继续向外增加。通过比较模型预测与X射线观测与朱雀，这表明平坦的熵分布，我们发现，CRs进行了0.7%的动能的气体远离集群。此外，在外围的CR压力可以是总压力的约40%。另一方面，如果熵分布在外围不是平坦的，如普朗克和ROSAT联合观测所示，携带的能量和CR压力应该比上述估计小得多。
Recently, gas entropy at the outskirts of galaxy clusters has attracted much attention. We propose that the entropy profiles could be used to study cosmic-ray (CR) acceleration around the clusters. If the CRs are effectively accelerated at the formation of clusters, the kinetic energy of infalling gas is consumed by the acceleration and the gas entropy should decrease. As a result, the entropy profiles become flat at the outskirts. If the acceleration is not efficient, the entropy should continue to increase outward. By comparing model predictions with X-ray observations with Suzaku, which show flat entropy profiles, we find that the CRs have carried≲ 7% of the kinetic energy of the gas away from the clusters. Moreover, the CR pressure at the outskirts can be≲ 40% of the total pressure. On the other hand, if the entropy profiles are not flat at the outskirts, as indicated by combined Plank and ROSAT observations, the carried energy and the CR pressure should be much smaller than the above estimations.