The evolution of each massive galaxy in the Universe is strictly connected to the activity of the supermassive black hole located at its centre. During their diverse accretion phases, SMBH occasionally eject plasma in the form of outflow and/or a collimated jet. It is estimated that only approximately 10% of active galactic nuclei (AGN) have the ability to launch powerful relativistic jets that shine in the radio band and emit synchrotron radiation. We refer to them as radio-loud (RL) AGNs. However, low power radio emission is also observed in radio-quiet (RQ) AGNs. Overall, AGN show a large variety of radio properties and morphologies, with sources exhibiting compact cores, jets, knots and extended diffuse emission in a wide range of strengths and sizes ranging from subparsec up to kiloparsec and even megaparsec scales. The incredible wealth of radio facilities currently available is offering a new panorama on the radio properties of RL and RQ AGN. In RL AGN, the number of sources showing episodes of restarting activity is rapidly increasing allowing for a more precise determination of the duty cycle of jet activity. In RQ AGN, the increase in sensitivity of radio interferometers and pioneering studies of radio light curves, are allowing us to investigate the radio nuclear properties and to probe the plethora of physical mechanisms, such as star formation, accretion disk winds, coronal disk emission, low-power jets. All these mechanisms will be probed with unprecedented sensitivity and spatial resolution with SKA, in particular by exploiting its VLBI capabilities at low and high frequencies.

Brief CV of Dr. Francesca Panessa:

She graduated at the University of Bologna in Astronomy, where she later earned her PhD in Astronomy. She has worked at the Institute of Astronomy in Cambridge (UK), at the Harvard Center for Astrophysics (Boston) and at the Instituto de Física de Cantabria, Spain. She is an expert in the study of the accretion and ejection phenomena in super massive black holes, in particular in the study of multi-frequency emission from radio to X-rays. She currently works at the Istituto di Astrofisica e Planetologia Spaziali - IAPS (INAF) in Rome, as a senior researcher within the GRAL group.