The SAMI Galaxy Survey:trends in [α/Fe] as a function of morphology and environment
We present a new set of index-based measurements of [α/Fe] for a sample of 2093 galaxies in the SAMI Galaxy Survey. Following earlier work, we fit a global relation between [α/Fe] and the galaxy velocity dispersion σ for red sequence galaxies, [α/Fe] = (0.378 ± 0.009)log 10 (σ/100) + (0.155 ± 0.003)...
Published in: | Monthly Notices of the Royal Astronomical Society |
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Main Authors: | , , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2022
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Subjects: | |
Online Access: | https://researchers.mq.edu.au/en/publications/a7c1c73f-a227-4502-8e6f-f28fe62747a0 https://doi.org/10.1093/mnras/stab3477 https://research-management.mq.edu.au/ws/files/200625860/198584095.pdf http://www.scopus.com/inward/record.url?scp=85126725583&partnerID=8YFLogxK http://purl.org/au-research/grants/arc/FT140100255 http://purl.org/au-research/grants/arc/CE170100013 http://purl.org/au-research/grants/arc/CE110001020 |
Summary: | We present a new set of index-based measurements of [α/Fe] for a sample of 2093 galaxies in the SAMI Galaxy Survey. Following earlier work, we fit a global relation between [α/Fe] and the galaxy velocity dispersion σ for red sequence galaxies, [α/Fe] = (0.378 ± 0.009)log 10 (σ/100) + (0.155 ± 0.003). We observe a correlation between the residuals and the local environmental surface density, whereas no such relation exists for blue cloud galaxies. In the full sample, we find that elliptical galaxies in high-density environments are α-enhanced by up to 0.057 ± 0.014 dex at velocity dispersions σ < 100 km s -1 , compared with those in low-density environments. This α-enhancement is morphology-dependent, with the offset decreasing along the Hubble sequence towards spirals, which have an offset of 0.019 ± 0.014 dex. At low velocity dispersion and controlling for morphology, we estimate that star formation in high-density environments is truncated ∼1 Gyr earlier than in low-density environments. For elliptical galaxies only, we find support for a parabolic relationship between [α/Fe] and σ, with an environmental α-enhancement of at least 0.03 dex. This suggests strong contributions from both environment and mass-based quenching mechanisms. However, there is no evidence for this behaviour in later morphological types. |
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