Interaction of radio lobes with the hot intracluster medium: Driving convective outflow in Hydra A

被引:130
作者
Nulsen, PEJ [1 ]
David, LP
McNamara, BR
Jones, C
Forman, WR
Wise, M
机构
[1] Univ Wollongong, Wollongong, NSW 2522, Australia
[2] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
[3] Ohio Univ, Dept Phys & Astron, Athens, OH 45701 USA
[4] MIT, Ctr Space Res, Cambridge, MA 02139 USA
关键词
cooling flows; galaxies : clusters : individual (Hydra A); intergalactic medium;
D O I
10.1086/338494
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The radio lobes of Hydra A lie within cavities surrounded by a rim of enhanced X-ray emission in the intra-cluster gas. Although the bright rim appears cooler than the surrounding gas, existing Chandra data do not exclude the possibility that the rim is produced by a weak shock. A temperature map shows that cool gas extends out along the radio axis of Hydra A. The age of the radio source and equipartition pressure of the radio lobe argue against a shock, and comparison with similar structure in the Perseus Cluster also suggests that the rim is cool. We show that the cool bright rim cannot be the result of shock-induced cooling or due to the effect of magnetic fields in shocks. The most likely source of low-entropy ( cool) gas is entrainment by the rising cavity. This requires some means of communicating the bouyant force on the cavity to the surrounding gas. The magnetic field required to produce the Faraday rotation in Hydra A has the appropriate properties for this if the Faraday screen is mainly in this bright rim. In Hydra A, the mass out flow due to the rising cavities could be sufficient to balance cooling-driven inflow, so preventing the build up of low-entropy gas in the cluster core.
引用
收藏
页码:163 / 173
页数:11
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