Starburst-AGN Connection: A Lesson from High-z Powerful Radio Galaxies
  Powerful radio galaxies at high redshift are highly useful in studies of early evolution of AGN-hosting galaxies because their observed optical and near infrared light are dominated by their stellar population rather than the nonthermal continuum emitted by the central engine of AGNs. In addition, the presence of AGN activity in them implies that a supermassive black hole has been already made in their nuclei. These properties allow us to investigate a possible starburst-AGN connection in early universe and then provide some crucial hints for the formation mechanism of supermassive black holes. Taking observational properties of high-z powerful radio galaxies into account, we discuss a possible formation mechanism of supermassive black holes in their nuclei. 
Yoshiaki Taniguchi