The Dramatic Size and Kinematic Evolution of Massive Early-Type Galaxies
  [ABRIDGED] We aim to provide a holistic view on the typical size and
kinematic evolution of massive early-type galaxies (ETGs), that encompasses
their high-$z$ star-forming progenitors, their high-$z$ quiescent counterparts,
and their configurations in the local Universe. Our investigation covers the
main processes playing a relevant role in the cosmic evolution of ETGs.
Specifically, their early fast evolution comprises: biased collapse of the low
angular momentum gaseous baryons located in the inner regions of the host dark
matter halo; cooling, fragmentation, and infall of the gas down to the radius
set by the centrifugal barrier; further rapid compaction via clump/gas
migration toward the galaxy center, where strong heavily dust-enshrouded
star-formation takes place and most of the stellar mass is accumulated;
ejection of substantial gas amount from the inner regions by feedback
processes, which causes a dramatic puffing up of the stellar component. In the
late slow evolution, passive aging of stellar populations and mass additions by
dry merger events occur. We describe these processes relying on prescriptions
inspired by basic physical arguments and by numerical simulations, to derive
new analytical estimates of the relevant sizes, timescales, and kinematic
properties for individual galaxies along their evolution. Then we obtain
quantitative results as a function of galaxy mass and redshift, and compare
them to recent observational constraints on half-light size $R_e$, on the ratio
$v/\sigma$ between rotation velocity and velocity dispersion (for gas and
stars) and on the specific angular momentum $j_\star$ of the stellar component;
we find good consistency with the available multi-band data in average values
and dispersion, both for local ETGs and for their $z\sim 1-2$ star-forming and
quiescent progenitors.
