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Coffee talks

Friday 12/07/2024 @ 11:30, Sala riunioni quarto piano e online (

Ramananda Santra (National center for radio astrophysics, Pune (India)), "Galaxy Clusters under uGMRT's Hawk-Eye: A closer look at their centers"

The universe, on the grandest of scales, forms a filamentary structure of dark matter, which evolves continuously due to the infalling and merging of smaller substructures of galaxy clusters and cluster groups that take place at the nodes of the cosmic web. Merging processes release tremendous amounts of kinetic energy of ~10^64 ergs and heat up the pre-existing relativistic fossil electrons. Cluster merger drives the relativistic electrons to ultra-relativistic speed and amplifies the existing cluster-wide magnetic fields. Interaction between ultra-relativistic electrons and magnetic fields gives rise to non-thermal radio emission in the form of large ~Mpc size diffuse cluster-wide radio sources, namely, radio halos and relics. Despite advancements in theoretical and observation techniques, their origins are not fully understood yet. In this talk, I will show a detailed analysis of the well-known radio halos (A521, PLCK171, A2163) with deep observations from uGMRT and JVLA, and how the results are useful in constraining the radio halo origin models.