SDSS-IV MaNGA: spatially resolved star formation histories in galaxies as a function of galaxy mass and type

Daniel Goddard, Daniel Thomas, Claudia Maraston, Kyle B. Westfall, James Etherington, Rogerio Riffel, Nicolas D. Mallmann, Zheng Zheng, Maria Argudo-Fernandez, Jianhui Lian, Matthew A. Bershady, Kevin Bundy, Niv Drory, David R. Law, Renbin Yan, David Wake, Anne-Marie Weijmans, Dmitry Bizyaev, Joel R. Brownstein, Richard R. LaneRoberto Maiolino, Karen L. Masters, Michael R. Merrifield, Christian Nitschelm, Kaike Pan, Alexandre Roman-Lopes, Thaisa Storchi-Bergmann, Donald P. Schneider

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Abstract

We study the internal gradients of stellar population properties within 1.5Re for a representative sample of 721 galaxies with stellar masses ranging between 109M to 1011.5M 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 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 are positive (∼0.09dex/Re) pointing to "outside-in" progression of star formation, while late-type galaxies have negative light-weighted age gradients (∼−0.11dex/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 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(logM)∼−0.2±0.05, compared to d(∇[Z/H])/d(logM)∼−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.
Original languageEnglish
Pages (from-to)4731-4758
JournalMonthly Notices of the Royal Astronomical Society
Volume466
Issue number4
Early online date31 Dec 2016
DOIs
Publication statusPublished - May 2017

Keywords

  • astro-ph.GA
  • galaxies: formation
  • galaxies: evolution
  • galaxies: elliptical and lenticular
  • cD
  • galaxies: stellar content
  • galaxies: star formation
  • RCUK
  • STFC

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