SDSS-IV MaNGA: global and local stellar population properties of
  elliptical galaxies
  We study the spatially resolved properties of 343 elliptical galaxies with
the MaNGA/SDSS-IV survey. We used the DESI Legacy Imaging Surveys for
morphological classification. Based on integrated spectroscopic properties and
colors, we classified seven classes of ellipticals. We inferred the stellar age
and metallicity ($Z$) gradients out to a 1.5 effective radius of classical "red
and dead", recently quenched, and blue star-forming ellipticals (CLEs, RQEs,
and BSFs), corresponding to 73%, 10%, and 4% of the sample, respectively. We
reconstructed their global and radial histories of star formation and mass
growth. We find the mass- and luminosity-weighted age gradients of CLEs are
nearly flat or mildly negative. The respective $Z$ gradients are negative,
being flatter as the mass is smaller. The more massive CLEs formed stars
earlier and quenched faster than the less massive ones. The CLEs show a weak
inside-out growth and a clear inside-out quenching. They finished their
quenching globally 3.8 $\pm$ 1.2 Gyr ago, with quenching time-scales of 3.4
$\pm$ 0.8 Gyr. At masses < 10$^{11}$ $M_{\bigodot}$, the age and $Z$ gradients
of the RQEs and BSFs are flatter than those of the CLEs but with larger
scatters. They show very weak inside-out growth and quenching, which is slow
and even not completed at $z\sim0$ for the BSFs. Instead, the massive RQEs show
an outside-in quenching and positive gradients in the luminosity-weighted age
and stellar metallicities. The RQEs of all masses quenched 1.2 $\pm$ 0.9 Gyr
ago on average. Our results for the CLEs are consistent with a two-phase
scenario where their inner parts formed by an early and coeval dissipative
collapse with a consequent burst of star formation and further quenching,
whereas the outer parts continued their assembly likely by dry mergers. We also
discuss some evolutionary scenarios for the RQE and BSF galaxies.
