Open AccessThermal conduction and reduced cooling flows in galaxy clusters
Author(s) -
Voigt L. M.,
Fabian A. C.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07285.x
Subject(s) - physics , thermal conduction , cooling flow , astrophysics , intracluster medium , thermal conductivity , galaxy cluster , turbulence , heat flux , inflow , galaxy , radiative cooling , luminosity , flux (metallurgy) , heat transfer , mechanics , thermodynamics , materials science , metallurgy
Conduction may play an important role in reducing cooling flows in galaxy clusters. We analyse a sample of 16 objects using Chandra data and find that a balance between electron conduction and cooling can exist in the hotter clusters ( T ≳ 5 keV) , provided that the plasma conductivity is close to the unhindered Spitzer value. In the absence of any additional heat sources, a reduced mass inflow must then develop in the cooler objects in the sample. We fit cooling flow models to deprojected spectra and compare the spectral mass deposition rates found to the values required to account for the excess luminosity, assuming Spitzer‐rate heat transfer over the observed temperature gradients. The measured mass inflow rates are insufficient to maintain energy balance in at least five clusters. However, emission from cooling gas may be partially absorbed. We also compute the flux supplied by turbulent heat transport and find conductivity profiles that follow a strikingly similar temperature dependence to the conductivity values required to prevent cooling. The larger‐scale turbulent motions implied by this process are required to have velocities of between 10 and 50 per cent of the speed of sound in the local intracluster gas.