Banerjee, Nilanjan and Sharma, Prateek (2014) Turbulence and cooling in galaxy cluster cores. In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 443 (1). pp. 687-697.
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We study the interplay between turbulent heating, mixing, and radiative cooling in an idealized model of cool cluster cores. Active galactic nuclei (AGN) jets are expected to drive turbulence and heat cluster cores. Cooling of the intracluster medium (ICM) and stirring by AGN jets are tightly coupled in a feedback loop. We impose the feedback loop by balancing radiative cooling with turbulent heating. In addition to heating the plasma, turbulence also mixes it, suppressing the formation of cold gas at small scales. In this regard, the effect of turbulence is analogous to thermal conduction. For uniform plasma in thermal balance (turbulent heating balancing radiative cooling), cold gas condenses only if the cooling time is shorter than the mixing time. This condition requires the turbulent kinetic energy to be a parts per thousand(3) the plasma internal energy; such high velocities in cool cores are ruled out by observations. The results with realistic magnetic fields and thermal conduction are qualitatively similar to the hydrodynamic simulations. Simulations where the runaway cooling of the cool core is prevented due to mixing with the hot ICM show cold gas even with subsonic turbulence, consistent with observations. Thus, turbulent mixing is the likely mechanism via which AGN jets heat cluster cores. The thermal instability growth rates observed in simulations with turbulence are consistent with the local thermal instability interpretation of cold gas in cluster cores.
| Item Type: | Journal Article |
|---|---|
| Publication: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY |
| Publisher: | OXFORD UNIV PRESS |
| Additional Information: | Copy right for this article belongs to the OXFORD UNIV PRESS, GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND |
| Keywords: | turbulence; methods: numerical; galaxies: clusters: intracluster medium |
| Department/Centre: | Division of Physical & Mathematical Sciences > Physics |
| Date Deposited: | 04 Sep 2014 10:49 |
| Last Modified: | 04 Sep 2014 10:49 |
| URI: | http://eprints.iisc.ac.in/id/eprint/49748 |
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