The MAGPI survey: The interdependence of the mass, star formation rate, and metallicity in galaxies at z ∼ 0.3

¹ University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180 Vienna, Austria
² Univ Lyon1, CNRS, Centre de Recherche Astrophysique de Lyon, 69230 Saint-Genis-Laval, France
³ Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611, Australia
⁴ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Canberra, ACT 2611, Australia
⁵ International Centre for Radio Astronomy (ICRAR), M468, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
⁶ Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney, NSW 2006, Australia
⁷ School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
⁸ School of Mathematical and Physical Sciences, Macquarie University, Sydney, NSW 2109, Australia
⁹ School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
¹⁰ University of Strasbourg, CNRS UMR 7550, Observatoire astronomique de Strasbourg, 67000 Strasbourg, France
¹¹ University of Strasbourg Institute for Advanced Study, 5 allée du Général Rouvillois, 67083 Strasbourg, France
¹² SISSA International School for Advanced Studies, Via Bonomea 265, 34136 Trieste, Italy
¹³ Department of Physics and Astronomy, University of the Western Cape, Cape Town 7535, South Africa
¹⁴ Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 München, Germany
¹⁵ Instituto de Astrofísica e Ciências do Espaço – Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal

Received: 14 May 2024
Accepted: 3 July 2024

Abstract

Aims. Star formation rates (SFRs), gas-phase metallicities, and stellar masses are crucial for studying galaxy evolution. The different relations resulting from these properties give insights into the complex interplay of gas inside galaxies and their evolutionary trajectory and current characteristics. We aim to characterize these relations at z ∼ 0.3, corresponding to a 3–4 Gyr lookback time, to gather insight into the galaxies’ redshift evolution.

Methods. We utilized optical integral field spectroscopy data from 65 emission-line galaxies from the MUSE large program MAGPI at a redshift of 0.28 < z < 0.35 (average redshift of z ∼ 0.3) and spanning a total stellar mass range of 8.2 < log(M_*/M_⊙) < 11.4. We measured emission line fluxes and stellar masses, allowing us to determine spatially resolved SFRs, gas-phase metallicities, and stellar mass surface densities. We derived the resolved star formation main sequence (rSFMS), resolved mass metallicity relation (rMZR), and resolved fundamental metallicity relation (rFMR) at z ∼ 0.3, and compared them to results for the local Universe.

Results. We find a relatively shallow rSFMS slope of ∼0.425 ± 0.014 compared to the expected slope at this redshift for an ordinary least square (OLS) fitting routine. For an orthogonal distance regression (ODR) routine, a much steeper slope of ∼1.162 ± 0.022 is measured. We confirm the existence of an rMZR at z ∼ 0.3 with an average metallicity located ∼0.03 dex above the local Universe’s metallicity. Via partial correlation coefficients, evidence is found that the local metallicity is predominantly determined by the stellar mass surface density and has a weak secondary (inverse) dependence on the SFR surface density Σ_SFR. Additionally, a significant dependence of the local metallicity on the total stellar mass M_* is found. Furthermore, we find that the stellar mass surface density Σ_* and M_* have a significant influence in determining the strength with which Σ_SFR correlates with the local metallicity. We observe that at lower stellar masses, there is a tighter correlation between Σ_SFR and the gas-phase metallicity, resulting in a more pronounced rFMR.