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Title: Exploring the properties of the M31 halo globular cluster system
Authors: Ferguson, A. M. N.
Mackey, A. D.
Tanvir, N. R.
Irwin, M. J.
Chapman, S. C.
Ibata, R. A.
Bridges, T.
Lewis, G. F.
Huxor, A. P.
First Published: 11-Jun-2011
Publisher: Oxford University Press (OUP)
Citation: Monthly Notices of the Royal Astronomical Society , 2011, 414 (1), pp. 770-780
Abstract: Following on from our discovery of a significant population of M31 outer halo globular clusters (GCs), and updates to the Revised Bologna Catalogue of M31 GCs, we investigate the GC system of M31 out to an unprecedented radius (≈120 kpc). We derive various ensemble properties, including the magnitude, colour and metallicity distributions, as well as the GC number density profile. One of our most significant findings is evidence for a flattening in the radial GC number density profile in the outer halo. Intriguingly, this occurs at a galactocentric radius of ∼2° (∼30 kpc) which is the radius at which the underlying stellar halo surface density has also been shown to flatten. The GCs which lie beyond this radius are remarkably uniform in terms of their blue (V−I)0 colours, consistent with them belonging to an ancient population with little to no metallicity gradient. Structural parameters are also derived for a sample of 13 newly discovered extended clusters (ECs), and we find the lowest luminosity ECs have magnitudes and sizes similar to Palomar-type GCs in the Milky Way halo. We argue that our findings provide strong support for a scenario in which a significant fraction of the outer halo GC population of M31 has been accreted.
DOI Link: 10.1111/j.1365-2966.2011.18450.x
ISSN: 0035-8711
eISSN: 1365-2966
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2011 the authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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