University of Minnesota
School of Physics & Astronomy

Cosmology Lunchtime Seminar

Monday, November 19th 2018
12:15 pm:
Speaker: Soumyajit Mandal, Case Western Reserve University
Subject: Ultra-steep-spectrum Sources in Galaxy Clusters

Low-frequency radio observations have revealed the presence of large-scale synchrotron emitting sources in galaxy clusters. Over the last decade it has become clear that these sources trace particles (re-)accelerated by shocks and turbulence generated during major merger events. However, the physics of these particle acceleration processes is still poorly understood. One of the main open questions is the fate of fossil relativistic electrons deposited in the intra-cluster medium, e.g., the lobes and tails of cluster radio galaxies. Are these fossil electrons re-accelerated by merger-induced shocks and turbulence? And is there a link to the generation of giant radio halos and relics? We have carried out GMRT follow-up observations of a unique sample of diffuse, ultra-steep-spectrum radio sources in galaxy clusters selected from the GMRT 150-MHz sky survey (TGSS) and follow up LOFAR, Chandra observation is underway. By determining their detailed properties, we aim to establish the origin of these sources, as well as their connection to ICM particle re-acceleration processes. In this talk I will present our search and preliminary findings about this sample of radio phoenixes, which is likely the tip of the iceberg of a large population of fossil plasma sources.

Faculty Host: Thomas W. Jones

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