We perform full spectrum fitting stellar population analysis and Jeans Anisotropic modelling ( JAM ) of the stellar kinematics for about 2000 early-type galaxies ( ETGs ) and spiral galaxies from the MaNGA DR14 sample .
Galaxies with different morphologies are found to be located on a remarkably tight mass plane which is close to the prediction of the virial theorem , extending previous results for ETGs .
By examining an inclined projection ( ‘ the mass-size ’ plane ) , we find that spiral and early-type galaxies occupy different regions on the plane , and their stellar population properties ( i.e .
age , metallicity and stellar mass-to-light ratio ) vary systematically along roughly the direction of velocity dispersion , which is a proxy for the bulge fraction .
Galaxies with higher velocity dispersions have typically older ages , larger stellar mass-to-light ratios and are more metal rich , which indicates that galaxies increase their bulge fractions as their stellar populations age and become enriched chemically .
The age and stellar mass-to-light ratio gradients for low-mass galaxies in our sample tend to be positive ( centre < outer ) , while the gradients for most massive galaxies are negative .
The metallicity gradients show a clear peak around velocity dispersion \log _ { 10 } \sigma _ { e } \approx 2.0 , which corresponds to the critical mass \sim 3 \times 10 ^ { 10 } M _ { \odot } of the break in the mass-size relation .
Spiral galaxies with large mass and size have the steepest gradients , while the most massive ETGs , especially above the critical mass M _ { crit } \ga 2 \times 10 ^ { 11 } M _ { \odot } , where slow rotator ETGs start dominating , have much flatter gradients .
This may be due to differences in their evolution histories , e.g .
mergers .