A mixture evolution scenario of the AGN radio luminosity function
  We propose a mixture evolution scenario to model the evolution of the radio luminosity function (RLF) of steep spectrum AGNs (active galactic nuclei) based on a Bayesian method. In this scenario, the shape of the RLF is determined by both the density and luminosity evolution. Our models indicate that the density evolution is positive until a redshift of $\thicksim 0.9$, at which point it becomes negative, while the luminosity evolution is positive to a higher redshift ($z \thicksim 5$ for model B and $z \thicksim 3.5$ for model C), where it becomes negative. Our mixture evolution model works well, and the modeled RLFs are in good agreement with previous determinations. The mixture evolution scenario can naturally explain the luminosity-dependent evolution of the RLFs. 
Zunli Yuan, Jiancheng Wang, Ming Zhou, Jirong Mao
astro-ph.HE astro-ph.GA