Galaxy Clusters: Mergers and Interaction with CMB

Galaxy Clusters: Mergers and Interaction with CMB

Galaxy Clusters: Mergers and Interaction with CMB
PI: Siddharth Malu and Abhirup Datta

The group led by Dr. Datta and Dr. Malu studies mergers or collisions between clusters of galaxies, which leads to copious amounts of radio emission, with a characteristic power law spectrum. Cluster-wide radio emission, which is found in central regions of the cluster, is known as a radio halo, and when found in peripheral regions of clusters/mergers, is known as a radio relic. There are several models that may explain the spectrum of this diffuse radio emission; however, the physical mechanisms that accelerate particles in these cluster mergers, and cause enhancements of the magnetic fields in the clusters, are not entirely understood. The group studies this diffuse radio emission at frequencies ranging from a few hundred MHz to ~ 20 GHz, to characterize its spectrum across a wide a range of frequencies, in order to gain insight into particle acceleration.

We also study inverse Compton scattering of cosmic microwave background photons from galaxy cluster electrons – known as the Sunyaev-Zeldovich Effect (SZ effect), as a way to characterize pressure structures. With X-ray observations of thermal plasma, and radio observations of non-thermal plasma in clusters, it is possible to characterize the energy distribution of the galaxy cluster plasma. This is the aim of SZ effect observations at cm-wavelengths – these are the lowest frequencies at which SZ effect can be measured. Currently, 2 PhD students are working in this area.

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