The evolution of radio jets across cosmic time
  We present predictions for the evolution of radio emission from Active
Galactic Nuclei (AGNs). We use a model that follows the evolution of
Supermassive Black Hole (SMBH) masses and spins, within the latest version of
the GALFORM semi-analytic model of galaxy formation. We use a Blandford-Znajek
type model to calculate the power of the relativistic jets produced by black
hole accretion discs, and a scaling model to calculate radio luminosities.
First, we present the predicted evolution of the jet power distribution,
finding that this is dominated by objects fuelled by hot halo accretion and an
ADAF accretion state for jet powers above $10^{32}\mathrm{W}$ at $z=0$, with
the contribution from objects fuelled by starbursts and in a thin disc
accretion state being more important for lower jet powers at $z=0$ and at all
jet powers at high redshifts ($z\geq3$). We then present the evolution of the
jet power density from the model. The model is consistent with current
observational estimates of jet powers from radio luminosities, once we allow
for the significant uncertainties in these observational estimates. Next, we
calibrate the model for radio emission to a range of observational estimates of
the $z=0$ radio luminosity function. We compare the evolution of the model
radio luminosity function to observational estimates for $0<z<6$, finding that
the predicted evolution is similar to that observed. Finally, we explore
recalibrating the model to reproduce luminosity functions of core radio
emission, finding that the model is in approximate agreement with the
observations.
