Thermal conduction and reduced cooling flows in galaxy clusters

By L. Voigt, A. C. Fabian. 2003

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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.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Galaxy-cluster gas-density distributions of the Representative XMM-Newton Cluster Structure Survey (REXCESS) (2008, background): “…in the inner regions of this sample is higher than see in other samples, particularly those dominated by cooling core clusters (e.g. Voigt & Fabian 2004, Sanderson et al. 2006), with a value ofσ/〈tcool〉 = 0.85 at 0.03R500 (as the cooling time profiles are dominated by the…”
X-ray Spectroscopy of Cooling Clusters (2005, methodology): “Voigt et al. (2002) (see also Kaastra et al. 2004 and Voigt & Fabian 2004) used the density and temperature profiles to deduce the heat transfer rate within the gas and thus the effective conductivity κeff required.”
Enhancement and Suppression of Heat Transfer by MHD Turbulence (2006, result): “This agrees well with the observations in Voigt & Fabian (2004).”
Filaments, Bubbles, and Weak Shocks in the Gaseous Atmosphere of M87 (2006, background): “Suggestions for heating include thermal conduction (e.g., Tucker & Rosner 1983; Bertschinger & Meiksin 1986; Gaetz 1989; David et al. 1992; Zakamska & Narayan 2003; Voigt & Fabian 2004) and cluster mergers (e.g., Fujita et al. 2004; but see Böhringer et al. 2004).”
Investigating AGN heating in a sample of nearby clusters (2006, background): “The viscous dissipation of the pressure waves allows the energy from the bubble creation to be dissipated far from the cluster centre, as gentle, continuous and distributed heating as required (Voigt & Fabian 2004).”
Feedback heating by cosmic rays in clusters of galaxies (2007, background): “…spectroscopically determined mass ⋆ E-mail: johnnie@physics.ucsb.edu † E-mail: peng@physics.ucsb.edu deposition rates are about 10 times smaller than the classic values estimated from X-ray luminosity within the cooling regions (Voigt & Fabian 2004), and thus limited to at most ∼ few × 10 M⊙ yr −1.”
ON THE ORIGIN OF THE EXTENDED Hα FILAMENTS IN COOLING FLOW CLUSTERS (2010, methodology): “The conductivity inside of the cooling radius for these four clusters ranges from κeff/κS = 0.3 to 2.3, while for the lone overlapping cluster with no Hα emission, the effective conductivity is κeff/κS = 0.2 (Voigt & Fabian 2004).”
On the prevalence of radio‐loud active galactic nuclei in brightest cluster galaxies: implications for AGN heating of cooling flows (2006, background): “Voigt & Fabian (2004) and Pope et al. (2006) show, however, that thermal conduction cannot provide sufficient heating to balance cooling in all clusters, and nor does the radial distribution of the heating match that required.”
STIRRING UP THE POT: CAN COOLING FLOWS IN GALAXY CLUSTERS BE QUENCHED BY GAS SLOSHING? (2009, background): “…collisions (e.g., Narayan & Medvedev 2001; Fabian, Voigt, & Morris 2002; Zakamska & Narayan 2003) and turbulent conduction (e.g., Cho et al. 2003; Voigt & Fabian 2004), and heating by cosmic rays (e.g., Colafrancesco & Marchegiani 2008); a recent review can be found in Peterson & Fabian (2006).”
A very deep Chandra observation of the Perseus cluster: shocks, ripples and conduction (2005, background): “It has been proposed and tested as a means for heating the gas from the outside, but found to be inadequate for clusters and regions below 5 keV (Kim & Narayan 2003; Voigt & Fabian 2004).”
Galaxy bimodality due to cold flows and shock heating (2004, background): “The cloud sizes and evolution are affected by thermal conductivity and dynamical processes (Voigt & Fabian 2004).”
Compressible turbulence in galaxy clusters: physics and stochastic particle re-acceleration (2007, background): “…to balance the cooling of cluster cores (Fujita, Matsumoto & Wada 2004), and the knowledge of the basic aspects of turbulence in galaxy clusters is also crucial to model the transport of heat and metals in the ICM (Narayan & Medvedev 2001; Cho et al., 2003; Voigt & Fabian 2004; Lazarian 2006b).”
Heating Hot Atmospheres with Active Galactic Nuclei (2007, background): “…and radiation (the fine-tuning problem; Stewart et al. 1984; Malagoli et al. 1987; Bregman & David 1988), there are several clusters where heat conduction cannot balance cooling throughout the core, even at the full Braginskii rate (Zakamska & Narayan 2003; Voigt & Fabian 2004; Wise et al. 2004).”
A semi-analytic model for the co-evolution of galaxies, black holes and active galactic nuclei (2008, background): “…processes that could suppress cooling in large-mass haloes have been suggested and explored, such as thermal conduction (Benson et al. 2003; Voigt & Fabian 2004), multiphase cooling (Maller & Bullock 2004), or heating by substructure or clumpy accretion (Khochfar & Ostriker 2007; Naab et…”