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The SLUGGS Survey: stellar kinematics, kinemetry and trends at large radii in 25 early-type galaxies
Monthly Notices of the Royal Astronomical Society (2016)
  • Caroline Foster, Australian Astronomical Observatory
  • Nicola Pastorello, Swinburne University of Technology
  • Joel Roediger, University of California, Santa Cruz
  • Jean P. Brodie, University of California Observatories
  • Duncan A. Forbes, Swinburne University of Technology
  • Sreeja S. Kartha, Swinburne University of Technology
  • Vincenzo Pota, INAF - Osservatorio Astronomico di Capodimonte
  • Aaron J. Romanowsky, San Jose State University
  • Lee R. Spitler, Australian Astronomical Observatory
  • Jay Strader, Michigan State University
  • Christopher Usher, Swinburne University of Technology
  • Jacob A. Arnold, University of California, Santa Cruz
Abstract
Due to longer dynamical time-scales, the outskirts of early-type galaxies retain the footprint of their formation and assembly. Under the popular two-phase galaxy formation scenario, an initial in situ phase of star formation is followed by minor merging and accretion of ex situ stars leading to the expectation of observable transitions in the kinematics and stellar populations on large scales. However, observing the faint galactic outskirts is challenging, often leaving the transition unexplored. The large-scale, spatially resolved stellar kinematic data from the SAGES Legacy Unifying Galaxies and GlobularS (SLUGGS) survey are ideal for detecting kinematic transitions. We present kinematic maps out to 2.6 effective radii on average, kinemetry profiles, measurement of kinematic twists and misalignments, and the average outer intrinsic shape of 25 SLUGGS galaxies. We find good overall agreement in the kinematic maps and kinemetry radial profiles with literature. We are able to confirm significant radial modulations in rotational versus pressure support of galaxies with radius so that the central and outer rotational properties may be quite different. We also test the suggestion that galaxies may be more triaxial in their outskirts and find that while fast rotating galaxies were already shown to be axisymmetric in their inner regions, we are unable to rule out triaxiality in their outskirts. We compare our derived outer kinematic information to model predictions from a two-phase galaxy formation scenario. We find that the theoretical range of local outer angular momentum agrees well with our observations, but that radial modulations are much smaller than predicted.
Keywords
  • galaxies: haloes,
  • galaxies: kinematics and dynamics,
  • galaxies: structure
Publication Date
March, 2016
DOI
10.1093/mnras/stv2947
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: http://dx.doi.org/10.1093/mnras/stv2947
Citation Information
Caroline Foster, Nicola Pastorello, Joel Roediger, Jean P. Brodie, et al.. "The SLUGGS Survey: stellar kinematics, kinemetry and trends at large radii in 25 early-type galaxies" Monthly Notices of the Royal Astronomical Society Vol. 457 Iss. 1 (2016) p. 147 - 171 ISSN: 1365-2966
Available at: http://works.bepress.com/aaron_romanowsky/90/