Quenching of Massive Disk Galaxies in the IllustrisTNG Simulation
  A rare population of massive disk galaxies have been found to invade the red
sequence dominated by early-type galaxies. These red/quenched massive disk
galaxies have recently gained great interest into their formation and origins.
The usually proposed quenching mechanisms, such as bar quenching and
environment quenching, seem not suitable for those bulge-less quenched disks in
low-density environment. In this paper, we use the IllustrisTNG-300 simulation
to investigate the formation of massive quenched central disk galaxies. It is
found that these galaxies contain less gas and harbor giant supermassive black
holes(SMBHs) (above $ 10^{8}M_{\odot}$) than their star forming counterparts.
By tracing their formation history, we found that quenched disk galaxies formed
early and preserved disk morphology for cosmological time scales. They have
experienced less than one major merger on average and it is mainly mini-mergers
(mass ratio $<$1/10) that contribute to the growth of their SMBHs. In the
Illustris-TNG simulation the black hole feedback mode switches from thermal to
kinetic feedback when the black hole mass is more massive than $\sim
10^{8}M_{\odot}$, which is more efficient to eject gas outside of the galaxy
and to suppress further cooling of hot gaseous halo. We conclude that kinetic
AGN feedback in massive red/quenched disk galaxy is the dominant quenching
mechanism.
