We present an analysis of the global stellar populations of galaxies in the SAMI (Sydney- AAO Multi-object Integral field spectrograph) Galaxy Survey. Our sample consists of 1319 galaxies spanning four orders of magnitude in stellar mass and includes all morphologies and environments. We derive luminosity-weighted, single stellar population equivalent stellar ages, metallicities and alpha enhancements from spectra integrated within one effective radius apertures. Variations in galaxy size explain the majority of the scatter in the age-mass and metallicity-mass relations. Stellar populations vary systematically in the plane of galaxy size and stellar mass, such that galaxies with high stellar surface mass density are older, more metal rich and alpha enhanced than less dense galaxies. Galaxies with high surface mass densities have a very narrow range of metallicities; however, at fixed mass, the spread in metallicity increases substantially with increasing galaxy size (decreasing density). We identify residual correlations with morphology and environment. At fixed mass and size, galaxies with late-type morphologies, small bulges and low Sérsic n are younger than early type, high n, high bulgeto- total galaxies. Both age and metallicity show small residual correlations with environment; at fixed mass and size, galaxies in denser environments or more massive haloes are older and somewhat more metal rich than those in less dense environments. We connect these trends to evolutionary tracks within the size-mass plane.
Bibliographical noteFunding Information:
NS thanks Richard McDermid for helpful discussions and the anonymous referee for their constructive suggestions about the manuscript. The SGS is based on observations made at the Anglo-Australian Telescope. The SAMI was developed jointly by the University of Sydney and the Australian Astronomical Observatory. The SAMI input catalogue is based on data taken from the Sloan Digital Sky Survey, theGAMASurvey and theVSTATLAS Survey. The SGS is funded in part by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and other participating institutions. The SGS website is http://sami-survey.org/. NS acknowledges the support of a University of Sydney Postdoctoral Research Fellowship. SB acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140101166). SMC acknowledges the support of an Australian Research Council Future Fellowship (FT100100457). RLD acknowledges travel and computer grants from Christ Church, Oxford and support from the Oxford Centre for Astrophysical Surveys that is funded by the Hintze Family Charitable Foundation. JvdS is funded under Bland-Hawthorn's ARC Laureate Fellowship (FL140100278). JTA acknowledges the award of a SIEF John Stocker Fellowship. MSO acknowledges the funding support from the Australian Research Council through a Future Fellowship (FT140100255). CF gratefully acknowledges funding provided by the Australian Research Council's Discovery Projects (grants DP150104329 and DP170100603). Support for AMM is provided by NASA through Hubble Fellowship grant #HST-HF2-51377 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. AJM gratefully acknowledges funding provided by the Australian Research Council's Discovery Projects (grant DP130103505). SKY acknowledges support from the Korean National Research Foundation (NRF-20171A2A1A05001116). This work was supported by the UK Science and Technology Facilities Council through the 'Astrophysics at Oxford' grant ST/K00106/1. This research made use of ASTROPY, a community-developed core PYTHON package for Astronomy (Astropy Collaboration, 2013, http://www.astropy.org).
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science