Issues for future work


  • estimate the AGN activity timescale along the cosmic evolution


  • disk-jet evolution:
    What kind of disks drive jets and what kind of disks do not? (Stepanovs & Fendt 2016)
  • cooling time threshold & thermal instability (McNamara et al 2016):
    Star formation and nebular emission are prevalent when the central atmospheric cooling time falls below $5 \times 10^8$ yr, or similarly, the central entropy parameter falls below $30 keV\,cm^2$ (Rafferty et al. 2008; Cavagnolo et al. 2008). Systems lying above the central cooling time threshold are usually devoid of cooling gas and star formation, while those below usually are not. The threshold may be related to the onset of thermal instability in the hot atmosphere (Voit et al. 2008) but the reasons for its numerical value are not understood.