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The outer halo globular cluster system of M31 - II. Kinematics

Veljanoski, J.; Mackey, Alasdair; Ferguson, A. M. N.; Huxor, A; Cote, P; Irwin, Mike; Tanvir, Nial R; Penarrubia, J; Bernard, E.J; Fardal, Mark; Martin, Nicolas F; Ibata, Rodrigo A

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We present a detailed kinematic analysis of the outer halo globular cluster system of the Andromeda galaxy (M31). Our basis for this is a set of new spectroscopic observations for 78 clusters lying at projected distances between Rproj ~ 20-140 kpc from the M31 centre. These are largely drawn from the recent Pan-Andromeda Archaeological Survey globular cluster catalogue; 63 of our targets have no previous velocity data. Via a Bayesian maximum likelihood analysis, we find that globular clusters...[Show more]

dc.contributor.authorVeljanoski, J.
dc.contributor.authorMackey, Alasdair
dc.contributor.authorFerguson, A. M. N.
dc.contributor.authorHuxor, A
dc.contributor.authorCote, P
dc.contributor.authorIrwin, Mike
dc.contributor.authorTanvir, Nial R
dc.contributor.authorPenarrubia, J
dc.contributor.authorBernard, E.J
dc.contributor.authorFardal, Mark
dc.contributor.authorMartin, Nicolas F
dc.contributor.authorIbata, Rodrigo A
dc.date.accessioned2015-12-13T22:27:54Z
dc.identifier.issn0035-8711
dc.identifier.urihttp://hdl.handle.net/1885/74158
dc.description.abstractWe present a detailed kinematic analysis of the outer halo globular cluster system of the Andromeda galaxy (M31). Our basis for this is a set of new spectroscopic observations for 78 clusters lying at projected distances between Rproj ~ 20-140 kpc from the M31 centre. These are largely drawn from the recent Pan-Andromeda Archaeological Survey globular cluster catalogue; 63 of our targets have no previous velocity data. Via a Bayesian maximum likelihood analysis, we find that globular clusters with Rproj > 30 kpc exhibit coherent rotation around the minor optical axis ofM31, in the same direction as more centrally located globular clusters, but with a smaller amplitude of 86±17 km s-1. There is also evidence that the velocity dispersion of the outer halo globular cluster system decreases as a function of projected distance from the M31 centre, and that this relation can be well described by a power law of index ≈-0.5. The velocity dispersion profile of the outer halo globular clusters is quite similar to that of the halo stars, at least out to the radius up to which there is available information on the stellar kinematics. We detect and discuss various velocity correlations amongst subgroups of globular clusters that lie on stellar debris streams in the M31 halo. Many of these subgroups are dynamically cold, exhibiting internal velocity dispersions consistent with zero. Simple Monte Carlo experiments imply that such configurations are unlikely to form by chance, adding weight to the notion that a significant fraction of the outer halo globular clusters in M31 have been accreted alongside their parent dwarf galaxies. We also estimate the M31 mass within 200 kpc via the Tracer Mass Estimator (TME), finding (1.2-1.6) ± 0.2 × 1012M⊙. This quantity is subject to additional systematic effects due to various limitations of the data, and assumptions built in into the TME. Finally, we discuss our results in the context of formation scenarios for the M31 halo.
dc.publisherBlackwell Publishing Ltd
dc.rightsAuthor/s retain copyright
dc.sourceMonthly Notices of the Royal Astronomical Society
dc.titleThe outer halo globular cluster system of M31 - II. Kinematics
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume442
dc.date.issued2014
local.identifier.absfor020100 - ASTRONOMICAL AND SPACE SCIENCES
local.identifier.ariespublicationU3488905xPUB3991
local.type.statusPublished Version
local.contributor.affiliationVeljanoski, J., University of Edinburgh
local.contributor.affiliationMackey, Alasdair, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationFerguson, A. M. N., University of Edinburgh
local.contributor.affiliationHuxor, A, Universität Heidelberg
local.contributor.affiliationCote, P, NRC Herzberg Institute of Astrophysics
local.contributor.affiliationIrwin, Mike, Cambridge University
local.contributor.affiliationTanvir, Nial R, University of Leicester
local.contributor.affiliationPenarrubia, J, University of Edinburgh
local.contributor.affiliationBernard, E.J , University of Edinburgh
local.contributor.affiliationFardal, Mark, University of Massachusetts
local.contributor.affiliationMartin, Nicolas F, University of Strasbourg
local.contributor.affiliationIbata, Rodrigo A, Universite de Strasbourg
local.bibliographicCitation.issue4
local.bibliographicCitation.startpage2929
local.bibliographicCitation.lastpage2950
local.identifier.doi10.1093/mnras/stu1055
local.identifier.absseo970102 - Expanding Knowledge in the Physical Sciences
dc.date.updated2015-12-11T08:35:41Z
local.identifier.scopusID2-s2.0-84904560374
local.identifier.thomsonID000339924900008
dcterms.accessRightsOpen Access
CollectionsANU Research Publications

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