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Heating rate profiles in galaxy clusters

Heating rate profiles in galaxy clusters
Heating rate profiles in galaxy clusters
In recent years evidence has accumulated suggesting that the gas in galaxy clusters is heated by non-gravitational processes. Here we calculate the heating rates required to maintain a physically motived mass flow rate, in a sample of seven galaxy clusters. We employ the spectroscopic mass deposition rates as an observational input along with temperature and density data for each cluster. On energetic grounds we find that thermal conduction could provide the necessary heating for A2199, Perseus, A1795 and A478. However, the suppression factor, of the classical Spitzer value, is a different function of radius for each cluster. Based on the observations of plasma bubbles we also calculate the duty cycles for each AGN, in the absence of thermal conduction, which can provide the required energy input. With the exception of Hydra-A it appears that each of the other AGNs in our sample require duty cycles of roughly 106-107 yrs to provide their steady-state heating requirements. If these duty cycles are unrealistic, this may imply that many galaxy clusters must be heated by very powerful Hydra-A type events interspersed between more frequent smaller-scale outbursts. The suppression factors for the thermal conductivity required for combined heating byAGN and thermal conduction are generally acceptable. However, these suppression factors still require ‘fine-tuning‘ of the thermal conductivity as a function of radius. As a consequence of this work we present the AGN duty cycle as a cooling flow diagnostic.
hydrodynamics, cooling flows, galaxies, active, clusters, individual, (virgo, A2199, perseus, hydra-a, A2597, A1795, A478)
1365-2966
1121-1131
Pope, Edward C.D.
d5272405-6747-452a-b1a5-9d18e45a0b9e
Pavlovski, Georgi
bcfbe814-a7b9-43bc-81bf-58fd2aa456c5
Kaiser, Christian R.
28e00576-1e5b-47f1-b24c-fa10689717ab
Fangohr, Hans
9b7cfab9-d5dc-45dc-947c-2eba5c81a160
Pope, Edward C.D.
d5272405-6747-452a-b1a5-9d18e45a0b9e
Pavlovski, Georgi
bcfbe814-a7b9-43bc-81bf-58fd2aa456c5
Kaiser, Christian R.
28e00576-1e5b-47f1-b24c-fa10689717ab
Fangohr, Hans
9b7cfab9-d5dc-45dc-947c-2eba5c81a160

Pope, Edward C.D., Pavlovski, Georgi, Kaiser, Christian R. and Fangohr, Hans (2006) Heating rate profiles in galaxy clusters. Monthly Notices of the Royal Astronomical Society, 367 (3), 1121-1131. (doi:10.1111/j.1365-2966.2006.10032.x).

Record type: Article

Abstract

In recent years evidence has accumulated suggesting that the gas in galaxy clusters is heated by non-gravitational processes. Here we calculate the heating rates required to maintain a physically motived mass flow rate, in a sample of seven galaxy clusters. We employ the spectroscopic mass deposition rates as an observational input along with temperature and density data for each cluster. On energetic grounds we find that thermal conduction could provide the necessary heating for A2199, Perseus, A1795 and A478. However, the suppression factor, of the classical Spitzer value, is a different function of radius for each cluster. Based on the observations of plasma bubbles we also calculate the duty cycles for each AGN, in the absence of thermal conduction, which can provide the required energy input. With the exception of Hydra-A it appears that each of the other AGNs in our sample require duty cycles of roughly 106-107 yrs to provide their steady-state heating requirements. If these duty cycles are unrealistic, this may imply that many galaxy clusters must be heated by very powerful Hydra-A type events interspersed between more frequent smaller-scale outbursts. The suppression factors for the thermal conductivity required for combined heating byAGN and thermal conduction are generally acceptable. However, these suppression factors still require ‘fine-tuning‘ of the thermal conductivity as a function of radius. As a consequence of this work we present the AGN duty cycle as a cooling flow diagnostic.

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Published date: April 2006
Keywords: hydrodynamics, cooling flows, galaxies, active, clusters, individual, (virgo, A2199, perseus, hydra-a, A2597, A1795, A478)

Identifiers

Local EPrints ID: 64965
URI: http://eprints.soton.ac.uk/id/eprint/64965
ISSN: 1365-2966
PURE UUID: 5306f578-913a-4ee3-88a5-3d7962d8aed1
ORCID for Hans Fangohr: ORCID iD orcid.org/0000-0001-5494-7193

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Date deposited: 27 Jan 2009
Last modified: 16 Mar 2024 03:09

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Contributors

Author: Edward C.D. Pope
Author: Georgi Pavlovski
Author: Christian R. Kaiser
Author: Hans Fangohr ORCID iD

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