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T. Markovic (NRAO/NMT), J.A. Eilek (NMT), F.N. Owen (NRAO)
The high central gas density in some galaxy clusters has been interpreted as a 'cooling flow', but searches have failed to find the large amount of cooling gas predicted by this model. We believe the situation is more complex.
We find that the X-ray surface brightness (SB) profiles of bright clusters can be divided into two categories -- cooling-core (CCC) and non-cooling (NCC) clusters. The SB of CCCs is well described by the cusp-like r1/4 profile, while the SB of NCCs is well fit by the core-like exponential or beta models. The SB profiles of both cluster types can be fit by gas in hydrostatic equilibrium in an NFW potential, if the CCC core radii are about six times smaller than the NCC core radii. This difference might reflect different merger histories for the two cluster types.
Radiative cooling in the CCCs must be offset by additional heating or pressure support in the cores. Such heating may come from cluster-center radio sources (CCRS). We know the current jet power in M87 is at least as large as the X-ray losses from the central ICM (Owen, Eilek & Kassim 2000). We know that nearly all (~90%) central galaxies in CCCs have currently active radio galaxies. We do not yet know the energetic role a typical CCRS plays in the ICM of the cooling core. To answer this question, we are observing a complete set of 23 CCCs using the VLA at 74, 323 and 1400 MHz. Our observations are designed to detect the diffuse halo emission which we postulate is present in most of the sources, and which is a direct sign of strong interaction between the jet and the ICM.
The author(s) of this abstract have provided an email address for comments about the abstract: tmarkovi@aoc.nrao.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.