Abstract
We estimate the thermal conductivity of a weakly collisional magnetized plasma with chaotic magnetic field fluctuations. When the fluctuation spectrum extends over two or more decades in wavevector, we find that thermal conduction is very efficient; the conduction coefficient is only a factor of ~5 below the classical Spitzer estimate. We suggest that conduction could play a significant role in cooling flows in clusters of galaxies.
Highlights
When the fluctuation spectrum extends over two or more decades in wave-vector, we find that thermal conduction is very efficient; the conduction coefficient is only a factor ∼ 5 below the classical Spitzer estimate
We suggest that conduction could play a significant role in cooling flows in clusters of galaxies
Hot X-ray-emitting gas is ubiquitous in clusters of galaxies (Sarazin 1988)
Summary
Hot X-ray-emitting gas is ubiquitous in clusters of galaxies (Sarazin 1988). Since the X-ray emission is energetically important in many clusters, it is believed that a significant amount of mass must continuously cool and drop out of the intracluster medium (Fabian 1994). Columns 6 and 7 give tcool and tSp. We see that if thermal conduction in a cluster is as efficient as in Spitzer’s theory, or even if it is a factor of a few less efficient, heat conduction will have a strong effect on the energetics of a cooling flow and perhaps will shut off mass dropout. The main problem with this idea is that the gas in a cluster is likely to be magnetized, and conventional wisdom says that magnetic fields severely suppress conduction relative to the Spitzer level. This is the topic of the present Letter.
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