2004/03/31 by Mateusz Ruszkowski, M. Brüggen, Marcus Bruggen +1 · 4 citations
Physics and Astronomy · #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Cluster (spacecraft) #Computational physics #Dissipation #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Intracluster medium #Mechanics #Optics #Physics #RADIUS #Radiative cooling #Radiative transfer #astro-ph
paper · pdf · doi:10.1086/424702
published as Astrophys.J. 615 (2004) 675-680 · accepted for ApJ
arxiv created 2004/07/21 · openalex publication_date 2004/11/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present three-dimensional simulations of viscous dissipation of active galactic nuclei (AGN)-induced gas motions and waves in clusters of galaxies. These simulations are motivated by recent detections of ripples in the Perseus and Virgo Clusters. Although the sound waves generated by buoyant bubbles decay with distance from the cluster center, we show that these waves can contribute substantially to offsetting the radiative cooling at distances significantly exceeding the bubble size. The energy flux of the waves declines more steeply with radius than the inverse-square law predicted by energy conservation, implying that dissipation plays an important role in tapping the wave energy. We show that such dispersing sound waves/weak shocks are detectable as ripples on unsharp-masked X-ray cluster maps and point out that the interfaces between the intracluster medium and old bubbles are also clearly detectable in unsharp-masked X-ray maps. This opens up the possibility of detecting fossil bubbles that are difficult to detect in radio emission. This mode of heating is consistent with other observational constraints, such as the presence of cool rims around the bubbles and the absence of strong shocks. Thus, the mechanism offers a way of heating clusters in a spatially distributed and gentle fashion. We also discuss the energy transfer between the central AGN and the surrounding medium. In our numerical experiments, we find that roughly 65% of the energy injected by the AGN is transferred to the intracluster medium, and approximately 25% of the injected energy is dissipated by viscous effects and contributes to heating of the gas. The overall transfer of heat from the AGN to the gas is comparable to the radiative cooling losses. The simulations were performed with the FLASH adaptive mesh refinement code.