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Accepted manuscript

The SAMI Galaxy Survey: fossil group centrals are no more likely to be slow rotators

Published online by Cambridge University Press:  23 October 2024

F. Scuccimarra*
Affiliation:
Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia
S.M. Croom
Affiliation:
Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)
J. van de Sande
Affiliation:
Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) School of Physics, University of New South Wales, NSW 2052, Australia
S. Barsanti
Affiliation:
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611, Australia
S. Brough
Affiliation:
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) School of Physics, University of New South Wales, NSW 2052, Australia
J.J. Bryant
Affiliation:
Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) Astralis-USydney, School of Physics, The University of Sydney, NSW 2006, Australia
L.C. Kimmig
Affiliation:
Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians Universität, Scheinerstr. 1, D-81679 München, Germany
C. del P. Lagos
Affiliation:
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) International Centre for Radio Astronomy Research, University of Western Australia, Crawley, WA 6009, Australia
R.-S. Remus
Affiliation:
Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians Universität, Scheinerstr. 1, D-81679 München, Germany
A. Ristea
Affiliation:
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) International Centre for Radio Astronomy Research, University of Western Australia, Crawley, WA 6009, Australia
S.M. Sweet
Affiliation:
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
S. Vaughan
Affiliation:
Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) Astronomy, Astrophysics and Astrophotonics Research Centre, Macquarie University, Sydney, NSW 2109, Australia Centre for Astrophysics and Supercomputing, School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
*
Author for correspondence: F. Scuccimarra, Email: [email protected].
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Abstract

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Simulations suggest that slow rotating galaxies are the result of galaxy-galaxy mergers that have a tendency to randomise stellar orbits. The exact pathway for slow rotator formation, however, is still unclear. Our aim is to see whether there is a relationship between fossil groups - whose central galaxies are thought to have undergone more major merging than other central galaxies - and the stellar kinematic properties of those central galaxies. We classify all galaxy groups in the GAMA redshift survey whose central galaxies were observed with SAMI as: i) fossil groups, ii) mass gap groups (fossil-like groups), and iii) groups that are not dynamically evolved (NDEGs, i.e. controls). We compare the following properties of centrals across the three different group types: spin (λRe), the fraction of slow rotators (fSR), and age. We also repeat our analysis on data from the EAGLE and MAGNETICUM hydrodynamical cosmological simulations. In SAMI, we find that the spin parameter, slow rotator fraction, and age are broadly consistent across our three group types, i.e. the fossil groups, mass gap groups and NDEGs. We do find a weak indication that fSR is slightly lower for fossil group centrals as compared to NDEG centrals. In contrast, in EAGLE and MAGNETICUM, fossil and mass gap group centrals typically have a significantly lower λRe than NDEG centrals. Our results for SAMI suggest that the types of mergers that form fossil groups are not the types of mergers that form slow rotators. Merger count may be less important for slow rotator formation than specific merger conditions, such as the gas content of progenitors. When and where the merging occurs are also suspected to play an important role in slow rotator formation, and these conditions may differ for fossil group formation.

Type
Research Article
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of the Astronomical Society of Australia