Science with an ngVLA: Young Radio AGN in the ngVLA Era
  Most massive galaxies are now thought to go through an Active Galactic
Nucleus (AGN) phase one or more times. Yet, the cause of triggering and the
variations in the intrinsic and observed properties of AGN population are still
poorly understood. Young, compact radio sources associated with accreting
supermassive black holes (SMBHs) represent an important phase in the life
cycles of jetted AGN for understanding AGN triggering and duty cycles. The
superb sensitivity and resolution of the ngVLA, coupled with its broad
frequency coverage, will provide exciting new insights into our understanding
of the life cycles of radio AGN and their impact on galaxy evolution. The high
spatial resolution of the ngVLA will enable resolved mapping of young radio AGN
on sub-kiloparsec scales over a wide range of redshifts. With broad continuum
coverage from 1 to 116 GHz, the ngVLA will excel at estimating ages of sources
as old as $30-40$ Myr at $z \sim 1$. In combination with lower-frequency ($\nu
< 1$ GHz) instruments such as ngLOBO and the Square Kilometer Array, the ngVLA
will robustly characterize the spectral energy distributions of young radio
AGN.
