The Most Predictive Physical Properties for the Stellar Population Radial Profiles of Nearby Galaxies

We present a study on the radial profiles of the D4000, luminosity-weighted stellar ages τL, and luminosity-weighted stellar metallicities [Z/H]L of 3654 nearby galaxies (0.01 < z < 0.15) using the IFU spectroscopic data from the MaNGA survey available in the SDSS DR15, in an effort to explore the connection between median stellar population radial gradients (i.e., ∇D4000, ∇τL, ∇[Z/H]L) out to ∼1.5 Re and various galaxy properties, including stellar mass (M ), specific star formation rate (sSFR), morphologies, and local environment. We find that M is the single most predictive physical property for ∇D4000 and ∇[Z/H]L. The most predictive properties for ∇τL are sSFR and, to a lesser degree, M . The environmental parameters, including local galaxy overdensities and central-satellite division, have virtually no correlation with stellar population radial profiles for the whole sample, but the ∇D4000 of star-forming satellite galaxies with M 1010 M exhibit a significant positive correlation with galaxy overdensities. Galaxies with lower sSFR have on average steeper negative stellar population gradients, and this sSFR dependence is stronger for more massive star-forming galaxies. The negative correlation between the median stellar population gradients and M are best described largely as segmented relationships, whereby median gradients of galaxies with log M 10.0 (with the exact value depending on sSFR) have much weaker mass dependence than galaxies with higher M . While the dependence of the radial gradients of ages and metallicities on T-Types and central stellar mass surface densities are generally not significant, galaxies with later T-Types or lower central mass densities tend to have significantly lower D4000, younger τL, and lower [Z/H]L across the radial ranges probed in this study.