ANISOTROPIC THERMAL CONDUCTION AND THE COOLING FLOW PROBLEM IN GALAXY CLUSTERS
- Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)
We examine the long-standing cooling flow problem in galaxy clusters with three-dimensional magnetohydrodynamics simulations of isolated clusters including radiative cooling and anisotropic thermal conduction along magnetic field lines. The central regions of the intracluster medium (ICM) can have cooling timescales of {approx}200 Myr or shorter-in order to prevent a cooling catastrophe the ICM must be heated by some mechanism such as active galactic nucleus feedback or thermal conduction from the thermal reservoir at large radii. The cores of galaxy clusters are linearly unstable to the heat-flux-driven buoyancy instability (HBI), which significantly changes the thermodynamics of the cluster core. The HBI is a convective, buoyancy-driven instability that rearranges the magnetic field to be preferentially perpendicular to the temperature gradient. For a wide range of parameters, our simulations demonstrate that in the presence of the HBI, the effective radial thermal conductivity is reduced to {approx}<10% of the full Spitzer conductivity. With this suppression of conductive heating, the cooling catastrophe occurs on a timescale comparable to the central cooling time of the cluster. Thermal conduction alone is thus unlikely to stabilize clusters with low central entropies and short central cooling timescales. High central entropy clusters have sufficiently long cooling times that conduction can help stave off the cooling catastrophe for cosmologically interesting timescales.
- OSTI ID:
- 21372039
- Journal Information:
- Astrophysical Journal, Vol. 703, Issue 1; Other Information: DOI: 10.1088/0004-637X/703/1/96; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANISOTROPY
CONVECTION
COOLING TIME
ENTROPY
GALAXY CLUSTERS
HEAT FLUX
INSTABILITY
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
RADIATIVE COOLING
SIMULATION
TEMPERATURE GRADIENTS
THERMAL CONDUCTION
THERMAL CONDUCTIVITY
THERMODYNAMICS
THREE-DIMENSIONAL CALCULATIONS
X-RAY GALAXIES
COOLING
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ENERGY TRANSFER
FLUID MECHANICS
GALAXIES
HEAT TRANSFER
HYDRODYNAMICS
MASS TRANSFER
MECHANICS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES