  We use the MaNGA integral-field spectroscopic survey of low-redshift galaxies
to compare the stellar populations of the bulge and disc components, identified
from their Sersic profiles, for various samples of galaxies. Bulge dominated
regions tend to be more metal-rich and have slightly older stellar ages than
their associated disc dominated regions. The metallicity difference is
consistent with the deeper gravitational potential in bulges relative to discs,
which allows bulges to retain more of the metals produced by stars. The age
difference is due to star formation persisting longer in discs relative to
bulges. Relative to galaxies with lower stellar masses, galaxies with higher
stellar masses tend to have bulge dominated regions that are more metal-rich
and older (in light-weighted measurements) than their disc dominated regions.
This suggests high-mass galaxies quench from the inside out, while lower-mass
galaxies quench across the whole galaxy simultaneously. Early-type galaxies
tend to have bulge dominated regions the same age as their disc dominated
regions, while late-type galaxies tend to have disc dominated regions
significantly younger than their bulge dominated regions. Central galaxies tend
to have a greater metallicity difference between their bulge dominated regions
and disc dominated regions than satellite galaxies at similar stellar mass.
This difference may be explained by central galaxies being subject to mergers
or extended gas accretion bringing new, lower-metallicity gas to the disc,
thereby reducing the average metallicity and age of the stars; quenching of
satellite discs may also play a role.
