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NRAO/Socorro Colloquium Series

Michael Wise

ASTRON

Feedback at the Working Surface: AGN Energy Deposition in Galaxy Clusters

Over the last decade, a combination of X-ray and radio observations have clearly shown that the intracluster medium (ICM) in cluster cores is being heated and redistributed by powerful radio sources driven by accretion onto the central, super-massive black hole (SMBH). These SMBHs are now believed to play a central role in galaxy formation through a feedback process that regulates both star formation in the host galaxy and the rate of accretion onto the black hole. Despite the very active work in this area, however, a number of fundamental open questions remain. In particular, the mechanisms and efficiency by which energy is transferred from the central radio source into the surrounding environment are not well understood. Similarly, how that energy is dispersed through the cluster and evolves over time is unclear. As I will show in this talk, multi-wavelength studies utilizing radio and X-ray data provide a powerful means to study this process at work in clusters and attempt to address some of these issues. Using recent results from such canonical objects as Cygnus A, I will show how these sorts of detailed multi-wavelength studies can constrain the energetics of this working surface between the radio plasma inside the cocoon shock and the X-ray emitting gas outside the shock. I will also discuss the constraints we can place on the emission mechanisms in the jets and hotspots based on the combined radio and X-ray spectra as well as the evolution of the interface region over time based on radio spectral aging and independent age estimates derived from various cavity features seen in the X-ray. Finally, time permitting, I will present preliminary results based on a sample of clusters identified in LOFAR’s first shallow, all-sky survey (Multi-frequency Snapshot Sky Survey or MSSS) and a look ahead to feedback studies with the full, deeper surveys to follow.



December 13, 2013
11:00 am

Array Operations Center Auditorium

All NRAO employees are invited to attend via video, available in Charlottesville Room 230, Green Bank Room 137 and Tucson N525.

Local Host: Frazer Owen

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