Journal Article

Sound waves in the intracluster medium

S. S. Shabala and P. Alexander

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 392, issue 4, pages 1413-1420
Published in print February 2009 | ISSN: 0035-8711
Published online January 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.14125.x
Sound waves in the intracluster medium

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We present an analysis of the behaviour of a perturbed radio cocoon. Comparisons with observations of sound waves detected in the Perseus and Virgo clusters suggest the separations of observed ripples correspond to the natural oscillation frequency of the cocoon. An energy injection rate consistent with active galactic nucleus power is required to offset the strong acoustic damping of cocoon oscillations, suggesting the sources are in equilibrium with the intracluster medium (ICM), and the oscillations are effectively undamped. Viscous dissipation of sound waves provides ICM heating that can quench cooling flows on time-scales greatly exceeding the oscillation time-scale. Thermal conductivity is likely to be heavily suppressed.

Keywords: waves; galaxies: active; galaxies: clusters: general; cooling flows; intergalactic medium

Journal Article.  6110 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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