An AGN's rendezvous with a radio relic
The galaxy clusters Abell 3411 and Abell 3412
Reinout van Weeren and his collaborators have discovered a cosmic event never seen before. Galaxy clusters can contain many different sources of radio emission and two key types are radio halos and relics. Both these are associated with cluster–cluster mergers. Halos are detected in the central region of the cluster, whereas relics are detected as on the periphery of clusters. By combining data from Chandra X-ray Observatory, the Giant Metrewave Radio Telescope, Jansky Very Large Array, and other telescopes, these authors have found source of seed synchrotron emitting electrons that produce radio emission as the shock propagates through the intra-cluster medium. The authors also demonstrated the expected change in characteristics of the radio emission at the location of these seed synchrotron emitting electrons are re-accelerated by the passage of the shock.
This work is published in Nature Astronomy, 2017.
Image description: An eruption from a supermassive black hole has been swept up into the collision between the galaxy clusters Abell 3411 and Abell 3412. This composite image contains X-rays from Chandra (blue) that reveals diffuse emission from multi-million-degree gas in the two clusters. Radio emission detected by the Giant Metrewave Radio Telescope in India (red) represents colossal shock-waves produced by the collision of the hot gas associated with the galaxy clusters. Optical data from the Subaru telescope atop Mauna Kea, Hawaii, shows galaxies and stars with a range of different colors. Credit: X-ray: NASA/CXC/SAO/R. van Weeren et al; Optical: NAOJ/Subaru; Radio: NCRA/TIFR/GMRT