SDSS-IV MaNGA: spatially resolved star formation histories in galaxies as a function of galaxy mass and type
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Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
OXFORD UNIV PRESS
Abstract
We study the internal gradients of stellar population propertieswithin 1.5 R-e for a representative sample of 721 galaxies, with stellar masses ranging between 10(9)M circle dot and 10(11.5)M circle dot 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 (similar to 0.09 dex/Re) pointing to ` outsidein' progression of star formation, while late-type galaxies have negative light-weighted age gradients (similar to-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 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(del[Z/H])/d(logM) similar to -0.2 +/- 0.05, compared to d(del[Z/H])/d(logM) similar to -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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Keywords
galaxies: elliptical and lenticular, cD, galaxies: evolution, galaxies: formation, galaxies: spiral, galaxies: star formation, galaxies: stellar content, STELLAR POPULATION GRADIENTS, DIGITAL SKY SURVEY, INSIDE-OUT GROWTH, METALLICITY GRADIENTS, COMA CLUSTER, ELLIPTIC GALAXIES, COLOR GRADIENTS, MORPHOLOGICAL CLASSIFICATIONS, ILLUSTRIS PROJECT, SPIRAL GALAXIES