The SAMI–Fornax Dwarfs Survey – III. Evolution of [α/Fe] in dwarfs, from Galaxy Clusters to the Local Group

Author(s)
J. Romero-Gómez, Reynier F. Peletier, J. A. L. Aguerri, Steffen Mieske, Nicholas Scott, Joss Bland-Hawthorn, Julia J. Bryant, Scott M. Croom, F. Sara Eftekhari, Jesús Falcón-Barroso, Michael Hilker, Glenn van de Ven, Aku Venhola
Abstract

Using very deep, high spectral resolution data from the SAMI Integral Field Spectrograph, we study the stellar population properties of a sample of dwarf galaxies in the Fornax Cluster, down to a stellar mass of 10

7 M

☉, which has never been done outside the Local Group. We use full spectral fitting to obtain stellar population parameters. Adding massive galaxies from the ATLAS

3D project, which we re-analysed, and the satellite galaxies of the Milky Way, we obtained a galaxy sample that covers the stellar mass range 10

4–10

12 M

☉. Using this large range, we find that the mass–metallicity relation is not linear. We also find that the [α/Fe]-stellar mass relation of the full sample shows a U-shape, with a minimum in [α/Fe] for masses between 10

9 and 10

10 M

☉. The relation between [α/Fe] and stellar mass can be understood in the following way: when the faintest galaxies enter the cluster environment, a rapid burst of star formation is induced, after which the gas content is blown away by various quenching mechanisms. This fast star formation causes high [α/Fe] values, like in the Galactic halo. More massive galaxies will manage to keep their gas longer and form several bursts of star formation, with lower [α/Fe] as a result. For massive galaxies, stellar populations are regulated by internal processes, leading to [α/Fe] increasing with mass. We confirm this model by showing that [α/Fe] correlates with clustercentric distance in three nearby clusters and also in the halo of the Milky Way.

Organisation(s)
Department of Astrophysics
External organisation(s)
Institute of Astrophysics of the Canary Islands, University of La Laguna, University of Groningen, European Southern Observatory (Chile), The University of Sydney, ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), European Southern Observatory (Germany), University of Oulu
Journal
Monthly Notices of the Royal Astronomical Society
Volume
522
Pages
130-150
No. of pages
21
ISSN
0035-8711
DOI
https://doi.org/10.1093/mnras/stad953
Publication date
06-2023
Peer reviewed
Yes
Austrian Fields of Science 2012
103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas
Astronomy and Astrophysics, Space and Planetary Science
Portal url
https://ucrisportal.univie.ac.at/en/publications/b15dc018-a8ba-474d-85a7-14dae735d1f4