A journey into the Perseus cluster of galaxies

The central black hole of active galaxies accretes large amounts of matter and powers jets of relativistic particles that can propagate beyond the host galaxy. Radio galaxies are particularly bright at ∼ GHz frequencies, when the accelerated electrons interact with the magnetic field and produce strong synchrotron emission. Such galaxies residing in clusters evolve in a hot, diffuse, X-ray emitting plasma (the intracluster medium, ICM) which is constantly perturbed, both internally by the outbursts of the central AGN, and externally from interactions with other clusters, groups, and individual galaxies. The ram pressure provided by the relative motion between a radio galaxy and the ICM can bend radio jets, producing a wide variety of distorted morphologies, clearly distinguishable from standard double radio galaxies: the so-called “bent-jet radio galaxies”. The advent of high-sensitivity low radio frequency facilities (such as e.g. VLA, GMRT, LOFAR, MWA, MeerKAT, ASKAP) has recently shed new light on our conception of galaxy cluster’s environments, resolving bent-jet radio galaxies and unveiling diffuse structures extending on large distances without a direct association with a host galaxy (“mini-halos”, “halos”, or “relics”), which origin remain unclear. Overall, the complete picture of diffuse radio emission in these environments is complex and the link between those various sources and the properties of clusters is not yet clear.

Located at a luminosity distance of 78.4 Mpc, the notorious Perseus cluster of galaxies has been the center of numerous discoveries, its proximity allowing high sensitivity and high resolution studies, revealing the physics of clusters at unprecedented levels of details. In this talk, I will present an overview of the deep multi-scale low radio frequency observations of the Perseus cluster obtained from the Karl G. Jansky Very Large Array. These observations have revealed a multitude of new structures associated with the radio lobes of several galaxies and the central mini-halo. Such work is paving the way for future radio telescopes such as the SKAO, which will uncover many more radio sources in these environments and open a new window on the unknown radio universe.

14/07/2022 - 12:30
Dr. Marie-Lou Gendron-Marsolais
Instituto de Astrofísica de Andalucía - CSIC, Granada , Spain