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SDSS-IV MaNGA: local and global chemical abundance patterns in early-type galaxies

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Chemical enrichment signatures strongly constrain galaxy formation and evolution, and a detailed understanding of abundance patterns provides clues regarding the nucleosynthetic production pathways of elements. Using integral-field spectroscopy from the MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) survey, we study radial gradients of chemical element abundances in detail. We use stacked spectra out to 1 Re of 366 early-type galaxies with masses 9.9−10.8 log M/M⊙ to probe the abundances of the elements C, N, Na, Mg, Ca, and Ti, relative to the abundance of Fe, by fitting stellar population models to a combination of Lick absorption indices. We find that C, Mg, and Ti trace each other both as a function of galaxy radius and galaxy mass. These similar C and Mg abundances within and across galaxies set a lower limit for star formation time-scales. Conversely, N and Ca are generally offset to lower abundances. The underabundance of Ca compared to Mg implies delayed enrichment of Ca through Type Ia supernovae, whereas the correlated behaviour of Ti and the lighter α elements, C and Mg, suggest contributions to Ti from Type II supernovae. We obtain shallow radial gradients in [Mg/Fe], [C/Fe], and [Ti/Fe], meaning that these inferences are independent of radius. However, we measure strong negative radial gradients for [N/Fe] and [Na/Fe], of up to −0.25 ± 0.05 and −0.29 ± 0.02 dex/Re, respectively. These gradients become shallower with decreasing galaxy mass. We find that N and Na abundances increase more steeply with velocity dispersion within galaxies than globally, while the other elements show the same relation locally and globally. This implies that the high Na and N abundances found in massive early-type galaxies are generated by internal processes within galaxies. These are strongly correlated with the total metallicity, suggesting metallicity-dependent Na enrichment and secondary N production in massive early-type galaxies.
Original languageEnglish
Pages (from-to)3420–3436
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume483
Issue number3
Early online date7 Dec 2018
DOIs
Publication statusPublished - 1 Mar 2019

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  • 1812.02753v1

    Rights statement: This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS following peer review. The version of record Taniya Parikh, Daniel Thomas, Claudia Maraston, Kyle B Westfall, Jianhui Lian, Amelia Fraser-McKelvie, Brett H Andrews, Niv Drory, Sofia Meneses-Goytia; SDSS-IV MaNGA: local and global chemical abundance patterns in early-type galaxies, Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 3, 1 March 2019, Pages 3420–3436 is available online at: https://doi.org/10.1093/mnras/sty3339.

    Accepted author manuscript (Post-print), 3.17 MB, PDF document

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