Skip to main content
The SLUGGS survey: the assembly histories of individual early-type galaxies
Monthly Notices of the Royal Astronomical Society (2016)
  • Duncan A. Forbes, Swinburne University of Technology
  • Aaron J. Romanowsky, San Jose State University
  • Nicola Pastorello, Swinburne University of Technology
  • Caroline Foster, Australian Astronomical Observatory
  • Jean P. Brodie, University of California Observatories
  • Jay Strader, Michigan State University
  • Christopher Usher, Liverpool John Moores University
  • Vincenzo Pota, University of California Observatories
Early-type (E and S0) galaxies may have assembled via a variety of different evolutionary pathways. Here, we investigate these pathways by comparing the stellar kinematic properties of 24 early-type galaxies from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey with the hydrodynamical simulations of Naab et al. In particular, we use the kinematics of starlight up to 4 effective radii (Re) as diagnostics of galaxy inner and outer regions, and assign each galaxy to one of six Naab et al. assembly classes. The majority of our galaxies (14/24) have kinematic characteristics that indicate an assembly history dominated by gradual gas dissipation and accretion of many gas-rich minor mergers. Three galaxies, all S0s, indicate that they have experienced gas-rich major mergers in their more recent past. One additional elliptical galaxy is tentatively associated with a gas-rich merger which results in a remnant galaxy with low angular momentum. Pathways dominated by gas-poor (major or minor) mergers dominate the mass growth of six galaxies. Most SLUGGS galaxies appear to have grown in mass (and size) via the accretion of stars and gas from minor mergers, with late major mergers playing a much smaller role. We find that the fraction of accreted stars correlates with the stellar mean age and metallicity gradient, but not with the slope of the total mass density profile. We briefly mention future observational and modelling approaches that will enhance our ability to accurately reconstruct the assembly histories of individual present-day galaxies.
  • galaxies: elliptical and lenticular,
  • cD,
  • galaxies: evolution,
  • galaxies: formation,
  • galaxies: kinematics and dynamics
Publication Date
April, 2016
Publisher Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
This article is also available online at the following link:
Citation Information
Duncan A. Forbes, Aaron J. Romanowsky, Nicola Pastorello, Caroline Foster, et al.. "The SLUGGS survey: the assembly histories of individual early-type galaxies" Monthly Notices of the Royal Astronomical Society Vol. 457 Iss. 2 (2016) p. 1242 - 1256 ISSN: 1365-2966
Available at: