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The SLUGGS survey: globular cluster kinematics in a ‘double sigma’ galaxy – NGC 4473
Monthly Notices of the Royal Astronomical Society (2015)
  • Adebusola B. Alabi, Swinburne University of Technology
  • Caroline Foster, Australian Astronomical Observatory
  • Duncan A. Forbes, Swinburne University of Technology
  • Aaron J. Romanowsky, San Jose State University
  • Nicola Pastorello, Swinburne University of Technology
  • Jean P. Brodie, University of California Observatories
  • Lee R. Spitler, Australian Astronomical Observatory
  • Jay Strader, Michigan State University
  • Christopher Usher, Swinburne University of Technology
NGC 4473 is a so-called double sigma (2σ) galaxy, i.e. a galaxy with rare, double peaks in its 2D stellar velocity dispersion. Here, we present the globular cluster (GC) kinematics in NGC 4473 out to ∼10Re (effective radii) using data from combined Hubble Space Telescope/Advanced Camera for Surveys and Subaru/Suprime-Cam imaging and Keck/Deep Imaging Multi-Object Spectrograph. We find that the 2σ nature of NGC 4473 persists up to 3Re, though it becomes misaligned to the photometric major axis. We also observe a significant offset between the stellar and GC rotation amplitudes. This offset can be understood as a co-addition of counter-rotating stars producing little net stellar rotation. We identify a sharp radial transition in the GC kinematics at ∼4Re suggesting a well defined kinematically distinct halo. In the inner region (<4Re), the blue GCs rotate along the photometric major axis, but in an opposite direction to the galaxy stars and red GCs. In the outer region (>4Re), the red GCs rotate in an opposite direction compared to the inner region red GCs, along the photometric major axis, while the blue GCs rotate along an axis intermediate between the major and minor photometric axes. We also find a kinematically distinct population of very red GCs in the inner region with elevated rotation amplitude and velocity dispersion. The multiple kinematic components in NGC 4473 highlight the complex formation and evolutionary history of this 2σ galaxy, as well as a distinct transition between the inner and outer components.
  • galaxies: evolution,
  • galaxies: kinematics and dynamics,
  • galaxies: star clusters: general
Publication Date
September, 2015
Publisher Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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Citation Information
Adebusola B. Alabi, Caroline Foster, Duncan A. Forbes, Aaron J. Romanowsky, et al.. "The SLUGGS survey: globular cluster kinematics in a ‘double sigma’ galaxy – NGC 4473" Monthly Notices of the Royal Astronomical Society Vol. 452 Iss. 2 (2015) p. 2208 - 2219 ISSN: 1365-2966
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