  We present a new analysis of the stellar mass function and morphology of
recently-quenched galaxies (RQGs), whose star formation has been recently
quenched for some reason. The COSMOS2015 catalog was exploited to select those
galaxies at 0.2 < z < 4.8, over 1.5 deg2 of the Cosmic Evolution Survey
(COSMOS) UltraVISTA field. This is the first time that RQGs are consistently
selected and studied in such a wide range of redshift. We find increasing
number density of RQGs with time in a broad mass range at z>1, while low-mass
RQGs start to grow very rapidly at z < 1. We also demonstrate that the
migration of RQGs may largely drive the evolution of the stellar mass function
of passive galaxies. Moreover, we find that the morphological type distribution
of RQGs are intermediate between those of star-forming and passive galaxies.
These results indicate that RQGs represent a major transitional phase of galaxy
evolution, in which star-forming galaxies turn into passive galaxies,
accompanied by the build up of spheroidal component.
