We study the internal gradients of stellar population properties within 1.5 Re for a representative sample of 721 galaxies, with stellar masses ranging between 109 M and 1011.5 M from the SDSS-IV MaNGA Integral-Field-Unit 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 quantify 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. Mass-weighted age gradients of early-types arepositive (∼0.09 dex/Re) pointing to ‘outside–in’ progression of star formation, while late-type galaxies have negative light-weighted age gradients (∼−0.11 dex/Re), 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 the 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 d(∇[Z/H])/d(log M) ∼ −0.2 ± 0.05 , compared to d(∇[Z/H])/d(log M) ∼ −0.05 ± 0.05  for early-types. This result suggests that the merger history plays a relatively small role in shaping metallicity gradients of galaxies.

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Published in Monthly Notices of the Royal Astronomical Society, v. 466, issue 4, p. 4731-4758.

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

The copyright holders have granted the permission for posting the article here.

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DG is supported by an STFC PhD studentship. MAB acknowledges NSF AST-1517006. AW acknowledges support from a Leverhulme Early Career Fellowship. DB is supported by grant RSCF-14-22-00041. RR thanks CNPq and Fapergs for financial support. RM acknowledges support by the Science and Technology Facilities Council (STFC) and the ERC Advanced Grant 695671 ‘QUENCH’.

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