The fourth generation of the Sloan

We study the internal gradients of stellar population properties within 1.5 R e for a representative sample of 721 galaxies with stellar masses ranging between 10 9 M to 10 11.5 M from the SDSS-IV MaNGA IFU survey. Through the use of our full spectral fitting code FIREFLY, we derive light and mass-weighted stellar population properties and their radial gradients, as well as full star formation and metal enrichment histories. We also quanfify the impact that different stellar population models and full spectral fitting routines have on the derived stellar population properties, and the radial gradient measurements. In our analysis, we find that age gradients tend to be shallow for both early-type and late-type galaxies. Massweighted age gradients of early-types are positive (∼ 0.09 dex/R e ) pointing to "outside-in" progression of star formation, while late-type galaxies have negative light-weighted age gradients (∼ −0.11 dex/R e ), suggesting an "inside-out" formation of discs. We detect negative metallicity gradients in both early and late-type galaxies, but these are significantly steeper in late-types, suggesting that radial dependence of chemical enrichment processes and the effect of gas inflow and metal transport are far more pronounced in discs. Metallicity gradients of both morphological classes correlate with galaxy mass, with negative metallicity gradients becoming steeper with increasing galaxy mass. The correlation with mass is stronger for late-type galaxies, with a slope of.05 ± 0.05 for early-types. This result suggests that the merger history plays a relatively small role in shaping metallicity gradients of galaxies.

We report the characterization of the first 62 MaNGA Active Galactic Nuclei (AGN) hosts in the Fifth Product Launch (MPL-5) and the definition of a control sample of non-active galaxies. This control sample -comprising two galaxies for each AGNwas selected in order to match the AGN hosts in terms of stellar mass, redshift, visual morphology and inclination. The stellar masses are in the range 9.4 < log (M/M ) < 11.5, and most objects have redshifts ≤ 0.08. The AGN sample is mostly comprised of low-luminosity AGN, with only 17 nuclei with L([OIII]λ 5007) ≥ 3.8 × 10 40 erg s −1 (that we call "strong AGN"). The stellar population of the control sample galaxies within the inner 1-3 kpc is dominated by the old (∼ 4 -13 Gyr) age component, with a small contribution of intermediate age (∼640-940 Myr) and young stars (≤ 40 Myr) to the total light at 5700Å. While the weaker AGN show a similar age distribution to that of the control galaxies, the strong AGN show an increased contribution of younger stars and a decreased contribution of older stars. Examining the relationship between the AGN stellar population properties and L([OIII]), we find that with increasing L([OIII]), the AGN exhibit a decreasing contribution from the oldest (>4 Gyr) stellar population relative to control galaxies, but have an increasing contribution from the younger components with ages ∼40 Myr. We also find a correlation of the mean age differences (AGN -control) with L([OIII]), in the sense that more luminous AGN are younger than the control objects, while the low-luminosity AGN seem to be older. These results support a connection between the growth of the galaxy bulge via formation of new stars and the growth of the Supermassive Black Hole via matter accretion in the AGN phase.