The SLUGGS Survey: stellar kinematics, kinemetry and trends at large radii in 25 early-type galaxies
Document Type
Article
Publication Date
March 2016
Publication Title
Monthly Notices of the Royal Astronomical Society
Volume
457
Issue Number
1
First Page
147
Last Page
171
DOI
10.1093/mnras/stv2947
Keywords
galaxies: haloes, galaxies: kinematics and dynamics, galaxies: structure
Disciplines
Astrophysics and Astronomy | External Galaxies
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.
Recommended Citation
Caroline Foster, Nicola Pastorello, Joel Roediger, Jean Brodie, Duncan Forbes, Sreeja Kartha, Vincenzo Pota, Aaron Romanowsky, Lee Spitler, Jay Strader, Christopher Usher, and Jacob Arnold. "The SLUGGS Survey: stellar kinematics, kinemetry and trends at large radii in 25 early-type galaxies" Monthly Notices of the Royal Astronomical Society (2016): 147-171. https://doi.org/10.1093/mnras/stv2947
Comments
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