Marsfield Lecture Theatre

Sarah White

Sarah White Colloquium: Evidence for AGN-powered radio emission in Radio-Quiet Quasars

Studying the interplay of accretion and star formation is crucial to our understanding of galaxy evolution. As we probe low radio luminosities, the two main populations are star-forming galaxies and radio-quiet quasars (RQQs). How they contribute to the total radio emission is under debate, with previous studies arguing that star formation dominates. In this talk I will describe two RQQ samples that demonstrate the importance of accretion-related radio emission in these objects. The first sample is selected from the VISTA Deep Extragalactic Observations (VIDEO) survey, whose depth allows the study of very low accretion rates and/or lower-mass black holes. A second sample is obtained from the Spitzer-Herschel Active Galaxy Survey, spanning a factor of ~100 in optical luminosity over a narrow redshift range at z ~ 1. This enables evolutionary effects to be decoupled when comparisons are made with the VIDEO sample. Using radio data from the Karl G. Jansky Very Large Array (JVLA), I find further support that the AGN makes a significant contribution to the radio emission in RQQs. In addition, the levels of accretion and star formation appear to be weakly correlated with each other, and with optical luminosity.