SDSS-IV MaNGA: environmental dependence of the Mgb/⟨Fe⟩-σ* relation for nearby galaxies

Zheng Zheng, Cheng Li, Shude Mao, Huiyuan Wang, Chao Liu, Houjun Mo, Zhen Yuan, Claudia Maraston, Daniel Thomas, Renbin Yan, Kevin Bundy, R. J. Long, Taniya Parikh, Grecco Oyarzún, Dmitry Bizyaev, Ivan Lacerna

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Abstract

We use a sample of ~3000 galaxies from the MaNGA MPL-7 internal data release to study the α abundance distribution within low-redshift galaxies. We use the Lick index ratio Mgb/⟨Fe⟩ as an αabundance indicator to study relationships between the α abundance distribution and galaxy properties such as effective stellar velocity dispersion within 0.3 effective radii (σ*), galaxy environment, and dark matter halo formation time (zf ). We find that (1) all galaxies show a tight correlation between Mgb/⟨Fe⟩ and σ*;(2) "old" (Hβ < 3) low-σ* galaxies in high local density environment and inner regions within galaxy groups are enhanced in Mgb/⟨Fe⟩, while "young" (Hβ > 3) galaxies and high-mass galaxies show no or less environmental dependence; (3) "old" galaxies with high-zf  show enhanced Mgb⟨Fe⟩/ over low- and medium-zf ; and (4) Mgb/⟨Fe⟩ gradients are close to zero and show dependence on σ* but no obvious dependence on the environment or zf . Our study indicates that stellar velocity dispersion or galaxy mass is the main parameter driving the Mgb/⟨Fe⟩ enhancement, although environments appear to have modest effects, particularly for low- and medium-mass galaxies.
Original languageEnglish
Article number63
Number of pages15
JournalAstrophysical Journal
Volume873
Issue number1
DOIs
Publication statusPublished - 5 Mar 2019

Keywords

  • galaxies: abundances
  • galaxies: evolution
  • galaxies: general
  • galaxies: statistics
  • galaxies: stellar content
  • galaxies: structure
  • RCUK
  • STFC
  • ST/N000668/1

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