THE THREE-DIMENSIONAL STRUCTURE OF THE M31 SATELLITE SYSTEM; STRONG EVIDENCE FOR AN INHOMOGENEOUS DISTRIBUTION OF SATELLITES
- Department of Physics and Astronomy, Macquarie University, NSW 2109 (Australia)
- Sydney Institute for Astronomy, School of Physics, A28, University of Sydney, Sydney NSW 2006 (Australia)
- Observatoire Astronomique de Strasbourg, Universite de Strasbourg, CNRS, UMR 7550, 11 rue de l'Universite, F-67000 Strasbourg (France)
- NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia, V9E 2E7 (Canada)
- Observatoire de Paris, LERMA, 61 Avenue de l'Observatoire, F-75014 Paris (France)
- Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom)
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
- Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, Nova Scotia, B3H 4R2 (Canada)
We undertake an investigation into the spatial structure of the M31 satellite system utilizing the distance distributions presented in a previous publication. These distances make use of the unique combination of depth and spatial coverage of the Pan-Andromeda Archaeological Survey to provide a large, homogeneous sample consisting of 27 of M31's satellites, as well as M31 itself. We find that the satellite distribution, when viewed as a whole, is no more planar than one would expect from a random distribution of equal size. A disk consisting of 15 of the satellites is however found to be highly significant, and strikingly thin, with an rms thickness of just 12.34{sup +0.75}{sub -0.43} kpc. This disk is oriented approximately edge-on with respect to the Milky Way and almost perpendicular to the Milky Way disk. It is also roughly orthogonal to the disk-like structure regularly reported for the Milky Way satellite system and in close alignment with M31's Giant Stellar Stream. A similar analysis of the asymmetry of the M31 satellite distribution finds that it is also significantly larger than one would expect from a random distribution. In particular, it is remarkable that 20 of the 27 satellites most likely lie on the Milky Way side of the galaxy, with the asymmetry being most pronounced within the satellite subset forming the aforementioned disk. This lopsidedness is all the more intriguing in light of the apparent orthogonality observed between the satellite disk structures of the Milky Way and M31.
- OSTI ID:
- 22167478
- Journal Information:
- Astrophysical Journal, Vol. 766, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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