Galaxy And Mass Assembly (GAMA): the mass-metallicity relationship

¹ European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago Chile
e-mail: cfoster@eso.org
² Centre for Astrophysics & Supercomputing, Swinburne University, Hawthorn, VIC 3122, Australia
³ Australian Astronomical Observatory, PO Box 296, Epping, NSW 1710, Australia
⁴ Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia
⁵ The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT, 2611, Australia
⁶ Institute of Cosmology and Gravitation (ICG), University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX, UK
⁷ International Centre for Radio Astronomy Research, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
⁸ School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
⁹ Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead, CH41 1LD, UK
¹⁰ Centre for Astronomy and Particle Theory, University of Nottingham, University Park, Nottingham NG7 2RD, UK
¹¹ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
¹² Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH, UK
¹³ Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
¹⁴ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁵ Department of Physics, Swiss Federal Institute of Technology (ETH-Zürich), 8093 Zürich, Switzerland
¹⁶ School of Physics, Monash University, Clayton, 3800 Victoria, Australia
¹⁷ Leiden University, P.O. Box 9500, 2300 RA Leiden, The Netherlands
¹⁸ Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
¹⁹ Department of Physics and Astronomy, Macquarie Uiversity, NSW 2109, Australia
²⁰ Astronomy Unit, Queen Mary University London, Mile End Rd, London E1 4NS, UK
²¹ South-East Physics Network (SEPnet)  
²² Max Planck Institute for Nuclear Physics (MPIK), Saupfercheckweg 1, 69117 Heidelberg, Germany

Received: 18 July 2012
Accepted: 7 September 2012

Abstract

Context. The mass-metallicity relationship (MMR) of star-forming galaxies is well-established, however there is still some disagreement with respect to its exact shape and its possible dependence on other observables.

Aims. We measure the MMR in the Galaxy And Mass Assembly (GAMA) survey. We compare our measured MMR to that measured in the Sloan Digital Sky Survey (SDSS) and study the dependence of the MMR on various selection criteria to identify potential causes for disparities seen in the literature.

Methods. We use strong emission line ratio diagnostics to derive oxygen abundances. We then apply a range of selection criteria for the minimum signal-to-noise in various emission lines, as well as the apparent and absolute magnitude to study variations in the inferred MMR.

Results. The shape and position of the MMR can differ significantly depending on the metallicity calibration and selection used. After selecting a robust metallicity calibration amongst those tested, we find that the mass-metallicity relation for redshifts 0.061 ≲ z ≲ 0.35 in GAMA is in reasonable agreement with that found in the SDSS despite the difference in the luminosity range probed.

Conclusions. In view of the significant variations of the MMR brought about by reasonable changes in the sample selection criteria and method, we recommend that care be taken when comparing the MMR from different surveys and studies directly. We also conclude that there could be a modest level of evolution over 0.06 ≤ z ≤ 0.35 within the GAMA sample.