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The effect of thermal conduction on the Virgo cluster

The effect of thermal conduction on the Virgo cluster
The effect of thermal conduction on the Virgo cluster
Thermal conduction has been suggested as a possible mechanism by which sufficient energy is supplied to the central regions of galaxy clusters to balance the effect of radiative cooling. Recent high resolution observations of the nearby Virgo cluster make it an ideal subject for an attempt to reproduce the properties of the cluster by numerical simulations, since most of the defining parameters are comparatively well known. Here we present the results of a simulated high-resolution, 3-d Virgo cluster for different values of thermal conductivity (1, 1/10, 1/100, 0 times the full Spitzer value). Starting from an initially isothermal cluster atmosphere we allow the cluster to evolve freely over timescales of roughly 1.3?4.7×109 yrs. Our results show that thermal conductivity at the Spitzer value can increase the central ICM radiative cooling time by a factor of roughly 3.6. In addition, for larger values of thermal conductvity the simulated temperature and density profiles match the observations significantly better than for the lower values. However, no physically meaningful value of thermal conductivity was able to postpone the cooling catastrophe (characterised by a rapid increase in the central density) for longer than a fraction of the Hubble time nor explain the absence of a strong cooling flow in the Virgo cluster today. We also calculate the effective adiabatic index of the cluster gas for both simulation and observational data and compare the values with theoretical expectations. Using this method it appears that the Virgo cluster is being heated in the cluster centre by a mechanism other than thermal conductivity. Based on this and our simulations it is also likely that the thermal conductvity is suppressed by a factor of at least 10 and probably more. Thus, we suggest that thermal conductvity, if present at all, has the effect of slowing down the evolution of the ICM, by radiative cooling, but only by a factor of a few.
hydrodynamics, galaxies, thermal conduction-galaxies: clusters: individual: virgo, galaxies: active, cooling flows flows
0035-8711
13-28
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 (2005) The effect of thermal conduction on the Virgo cluster. Monthly Notices of the Royal Astronomical Society, 364 (1), 13-28. (doi:10.1111/j.1365-2966.2005.09449.x).

Record type: Article

Abstract

Thermal conduction has been suggested as a possible mechanism by which sufficient energy is supplied to the central regions of galaxy clusters to balance the effect of radiative cooling. Recent high resolution observations of the nearby Virgo cluster make it an ideal subject for an attempt to reproduce the properties of the cluster by numerical simulations, since most of the defining parameters are comparatively well known. Here we present the results of a simulated high-resolution, 3-d Virgo cluster for different values of thermal conductivity (1, 1/10, 1/100, 0 times the full Spitzer value). Starting from an initially isothermal cluster atmosphere we allow the cluster to evolve freely over timescales of roughly 1.3?4.7×109 yrs. Our results show that thermal conductivity at the Spitzer value can increase the central ICM radiative cooling time by a factor of roughly 3.6. In addition, for larger values of thermal conductvity the simulated temperature and density profiles match the observations significantly better than for the lower values. However, no physically meaningful value of thermal conductivity was able to postpone the cooling catastrophe (characterised by a rapid increase in the central density) for longer than a fraction of the Hubble time nor explain the absence of a strong cooling flow in the Virgo cluster today. We also calculate the effective adiabatic index of the cluster gas for both simulation and observational data and compare the values with theoretical expectations. Using this method it appears that the Virgo cluster is being heated in the cluster centre by a mechanism other than thermal conductivity. Based on this and our simulations it is also likely that the thermal conductvity is suppressed by a factor of at least 10 and probably more. Thus, we suggest that thermal conductvity, if present at all, has the effect of slowing down the evolution of the ICM, by radiative cooling, but only by a factor of a few.

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Published date: November 2005
Keywords: hydrodynamics, galaxies, thermal conduction-galaxies: clusters: individual: virgo, galaxies: active, cooling flows flows

Identifiers

Local EPrints ID: 65016
URI: http://eprints.soton.ac.uk/id/eprint/65016
ISSN: 0035-8711
PURE UUID: 3bca3c66-750f-45c3-8089-145cdc863308
ORCID for Hans Fangohr: ORCID iD orcid.org/0000-0001-5494-7193

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Date deposited: 27 Jan 2009
Last modified: 03 Dec 2019 01:54

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