On the origin of radio emission in radio-quiet AGN and their connection to X-rays

Abstract

The accretion-ejection mechanism acting in Active Galactic Nuclei (AGN) is one of the main astrophysical open issues, being connected to the role of AGN feedback in galaxy formation evolution studies. The X-ray emission in AGN, associated with the accretion flow, is strongly coupled with the radio emission, associated with a jet. Strong correlations between the radio and the X-ray luminosities are found both in radio-loud (RL) and in radio-quiet (RQ) AGN, despite the fact that in RQ AGN jets are often absent or very weak. For two well defined and complete samples of low and high luminosity AGN, we have investigated the origin of the radio emission. In particular, for the low luminosity AGN sample, I will present the results from the first census of VLBI sub-parsec cores of a complete sample of radio-quiet Seyfert galaxies. Interestingly, at milli arc-seconds scales the radio emission does not seem to correlate with X-rays anymore. Show more