Abstract

Dwarf satellite galaxies are thought to be the remnants of the population of primordial structures that coalesced to form giant galaxies like the Milky Way1. It has previously been suspected2 that dwarf galaxies may not be isotropically distributed around our Galaxy, because several are correlated with streams of H i emission, and may form coplanar groups3. These suspicions are supported by recent analyses4,5,6,7. It has been claimed7 that the apparently planar distribution of satellites is not predicted within standard cosmology8, and cannot simply represent a memory of past coherent accretion. However, other studies dispute this conclusion9,10,11. Here we report the existence of a planar subgroup of satellites in the Andromeda galaxy (M 31), comprising about half of the population. The structure is at least 400 kiloparsecs in diameter, but also extremely thin, with a perpendicular scatter of less than 14.1 kiloparsecs. Radial velocity measurements12,13,14,15 reveal that the satellites in this structure have the same sense of rotation about their host. This shows conclusively that substantial numbers of dwarf satellite galaxies share the same dynamical orbital properties and direction of angular momentum. Intriguingly, the plane we identify is approximately aligned with the pole of the Milky Way’s disk and with the vector between the Milky Way and Andromeda.

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References

  1. 1.

    , , & Where are the missing galactic satellites? Astrophys. J. 522, 82–92 (1999)

  2. 2.

    Dwarf galaxies and globular clusters in high velocity hydrogen streams. Mon. Not. R. Astron. Soc. 174, 695–710 (1976)

  3. 3.

    & Ghostly streams from the formation of the Galaxy’s halo. Mon. Not. R. Astron. Soc. 275, 429–442 (1995)

  4. 4.

    , & The spatial distribution of the Milky Way and Andromeda satellite galaxies. Mon. Not. R. Astron. Soc. 374, 1125–1145 (2007)

  5. 5.

    , & The orbital poles of Milky Way satellite galaxies: a rotationally supported disk of satellites. Astrophys. J. 680, 287–294 (2008)

  6. 6.

    , & Discs of satellites: the new dwarf spheroidals. Mon. Not. R. Astron. Soc. 394, 2223–2228 (2009)

  7. 7.

    , & The VPOS: a vast polar structure of satellite galaxies, globular clusters and streams around the Milky Way. Mon. Not. R. Astron. Soc. 423, 1109–1126 (2012)

  8. 8.

    et al. Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: cosmological interpretation. Astrophys. J. 192 (Suppl.). 18 (2011)

  9. 9.

    , , & The anisotropic distribution of galactic satellites. Astrophys. J. 629, 219–232 (2005)

  10. 10.

    , , & The link between galactic satellite orbits and subhalo accretion. Mon. Not. R. Astron. Soc. 413, 3013–3021 (2011)

  11. 11.

    , , , & The missing massive satellites of the Milky Way. Mon. Not. R. Astron. Soc. 424, 2715–2721 (2012)

  12. 12.

    et al. The scatter about the ’Universal’ dwarf spheroidal mass profile: a kinematic study of the M31 satellites And V and And VI. Mon. Not. R. Astron. Soc. 417, 1170–1182 (2011)

  13. 13.

    et al. The SPLASH survey: spectroscopy of 15 M31 dwarf spheroidal satellite galaxies. Astrophys. J. 752, 45 (2012)

  14. 14.

    The observed properties of dwarf galaxies in and around the Local Group. Astron. J. 144, 4 (2012)

  15. 15.

    et al. The non-universal dSpH mass profile? A kinematic study of the Andromeda dwarf spheroidal system. Mon. Not. R. Astron. Soc (submitted)

  16. 16.

    et al. The remnants of galaxy formation from a panoramic survey of the region around M 31. Nature 461, 66–69 (2009)

  17. 17.

    et al. PAndAS’ progeny: extending the M31 dwarf galaxy cabal. Astrophys. J. 732, 76 (2011)

  18. 18.

    , & The tip of the red giant branch as a distance indicator for resolved galaxies. Astrophys. J. 417, 553–559 (1993)

  19. 19.

    et al. A Bayesian approach to locating the red giant branch tip magnitude. I. Astrophys. J. 740, 69 (2011)

  20. 20.

    Conn, A. R. et al. A Bayesian approach to locating the red giant branch tip magnitude. II. Distances to the satellites of M31. Astrophys. J. 758, 11 (2012). 1209.4952

  21. 21.

    & The satellite distribution of M31. Mon. Not. R. Astron. Soc. 365, 902–914 (2006)

  22. 22.

    et al. Discovery of Andromeda XIV: a dwarf spheroidal dynamical rogue in the Local Group? Astrophys. J. Lett. 670, L9–L12 (2007)

  23. 23.

    & The anisotropic distribution of M31 satellite galaxies: a polar great plane of early-type companions. Astron. J. 131, 1405–1415 (2006)

  24. 24.

    & M31 transverse velocity and local group mass from satellite kinematics. Astrophys. J. 678, 187–199 (2008)

  25. 25.

    Dark matter in the Milky Way’s dwarf spheroidal satellites. Preprint at (2012)

  26. 26.

    , , & An advanced, three-dimensional plotting library for astronomy. Publ. Astron. Soc. Aust. 23, 82–93 (2006)

Download references

Acknowledgements

We thank the staff of the Canada-France-Hawaii Telescope for taking the PAndAS data, and for their continued support throughout the project. We thank one of our referees, B. Tully, for pointing out that IC 1613 could also be associated to the planar structure. R.A.I. and D.V.G. gratefully acknowledge support from the Agence Nationale de la Recherche though the grant POMMME, and would like to thank B. Famaey for discussions. G.F.L. thanks the Australian Research Council for support through his Future Fellowship and Discovery Project. This work is based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada–France–Hawaii Telescope, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. Some of the data presented here were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

Author information

Affiliations

  1. Observatoire Astronomique de Strasbourg, 11 rue de l’Université, F-67000 Strasbourg, France

    • Rodrigo A. Ibata
    •  & Nicolas F. Martin
  2. Sydney Institute for Astronomy, School of Physics, A28, The University of Sydney, New South Wales 2006, Australia

    • Geraint F. Lewis
  3. Department of Physics and Astronomy, Macquarie University, New South Wales 2109, Australia

    • Anthony R. Conn
  4. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK

    • Michael J. Irwin
  5. NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia, V9E 2E7, Canada

    • Alan W. McConnachie
  6. Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, Nova Scotia, B3H 4R2, Canada

    • Scott C. Chapman
  7. Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

    • Michelle L. Collins
    •  & Nicolas F. Martin
  8. University of Massachusetts, Department of Astronomy, LGRT 619-E, 710 North Pleasant Street, Amherst, Massachusetts 01003-9305, USA

    • Mark Fardal
  9. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

    • Annette M. N. Ferguson
  10. Lycée International des Pontonniers, 1 rue des Pontonniers, F-67000 Strasbourg, France

    • Neil G. Ibata
  11. The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek, Australian Capital Province 2611, Australia

    • A. Dougal Mackey
  12. Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia, V8P 5C2, Canada

    • Julio Navarro
  13. Department of Physics and Astronomy, University of California, Los Angeles, PAB, 430 Portola Plaza, Los Angeles, California 90095-1547, USA

    • R. Michael Rich
  14. LERMA, UMR CNRS 8112, Observatoire de Paris, 61 Avenue de l’Observatoire, 75014 Paris, France

    • David Valls-Gabaud
  15. Department of Physics, Engineering Physics, and Astronomy, Queen’s University, Kingston, Ontario, K7L 3N, Canada

    • Lawrence M. Widrow

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Contributions

All authors assisted in the development and writing of the paper. In addition, the structural and kinematic properties of the dwarf population, and the significance of the Andromeda plane were determined by R.A.I., G.F.L. and A.R.C., based on distances determined by the same group (as part of the PhD research of A.R.C.). In addition, A.W.M. is the Principal Investigator of PAndAS; M.J.I. and R.A.I. led the data processing effort; R.A.I. was the Principal Investigator of an earlier CFHT MegaPrime/MegaCam survey, which PAndAS builds on (which included S.C.C., A.M.N.F., M.J.I., G.F.L., N.F.M. and A.W.M.). R.M.R. is Principal Investigator of the spectroscopic follow-up with the Keck Telescope. M.L.C. and S.C.C. led the analysis of the kinematic determination of the dwarf population, and N.F.M. led the detection of the dwarf population from PAndAS data. N.G.I. performed the initial analysis of the satellite kinematics.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Rodrigo A. Ibata.

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DOI

https://doi.org/10.1038/nature11717

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