The duty cycle of radio galaxies revealed by LOFAR: remnant and
  restarted radio source populations in the Lockman Hole
  Feedback from radio jets associated with Active Galactic Nuclei (AGN) plays a
profound role in the evolution of galaxies. Kinetic power of these radio jets
appears to show temporal variation, but the mechanism(s) responsible for this
process are not yet clear. Recently, the LOw Frequency ARray (LOFAR) has
uncovered large populations of active, remnant and restarted radio jet
populations. By focusing on LOFAR data in the Lockman Hole, in this work we use
the Radio AGN in Semi-Analytic Environments (RAiSE) dynamical model to present
the first self-consistent modelling analysis of active, remnant and restarted
radio source populations. Consistent with other recent work, our models predict
that remnant radio lobes fade quickly. Any high (>10 percent) observed fraction
of remnant and restarted sources therefore requires a dominant population of
short-lived jets. We speculate that this could plausibly be provided by
feedback-regulated accretion.
