The potential role of NGC 205 in generating Andromeda's vast thin corotating plane of satellite galaxies

Garry W. Angus, Paul Coppin, Gianfranco Gentile, Antonaldo Diaferio

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7 Citations (Scopus)


The Andromeda galaxy is observed to have a system of two large dwarf ellipticals and ~13 smaller satellite galaxies that are currently corotating in a thin plane, in addition to 2 counterrotating satellite galaxies. We explored the consistency of those observations with a scenario where the majority of the corotating satellite galaxies originated from a subhalo group, where NGC 205 was the host and the satellite galaxies occupied dark matter sub-subhaloes. We ran N-body simulations of a close encounter between NGC 205 and M31. In the simulations, NGC 205 was surrounded by massless particles to statistically sample the distribution of the subsubhaloes expected in a subhalo that has a mass similar to NGC 205. We made Monte Carlo samplings and found that, using a set of reference parameters, the probability of producing a thinner distribution of sub-subhaloes than the observed NGC 205 + 15 smaller satellites (thus including the two counter-rotators, but excluding M32) increased from <10-8 for the initial distribution to ~10-2 at pericentre. The probability of the simulated sub-subhaloes occupying the locations of the observed corotating satellites in the line-of-sight velocity versus projected on-sky distance plane is at most 2 × 10-3 for 11 out of 13 satellites. Increasing the mass of M31 and the extent of the initial distribution of sub-subhaloes gives a maximum probability of 4 × 10-3 for all 13 corotating satellites, but the probability of producing the thinness would drop to ~10-3.

Original languageEnglish
Article numberstw1822
Pages (from-to)3221-3242
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - Nov 1 2016

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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