2005/01/31 by J. I. Read, Ben Moore · 3 citations
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Dark matter #Dark matter halo #Flattening #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy rotation curve #Halo #Sagittarius #Space Technology and Applications #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2005.09232.x
published as Mon.Not.Roy.Astron.Soc. 361 (2005) 971-976 · 7 pages, 3 figures. Final version accepted for publication in MNRAS. The modelling of the Sagittarius stream has been improved, but otherwise the conclusions remain the same
arxiv created 2005/05/26 · openalex publication_date 2005/07/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We compare orbits in a thin axisymmetric disc potential in Modified Newtonian Dynamics (MOND) with those in a thin disc plus near-spherical dark matter halo predicted by a ΛCDM cosmology. Remarkably, the amount of orbital precession in MOND is nearly identical to that which occurs in a mildly oblate CDM Galactic halo (potential flattening q= 0.9), consistent with recent constraints from the Sagittarius stream. Since very flattened mass distributions in MOND produce rounder potentials than in standard Newtonian mechanics, we show that it will be very difficult to use the tidal debris from streams to distinguish between a MOND galaxy and a standard CDM galaxy with a mildly oblate halo. If a galaxy can be found with either a prolate halo or one that is more oblate than q∼ 0.9 this would rule out MOND as a viable theory. Improved data from the leading arm of the Sagittarius dwarf—which samples the Galactic potential at large radii—could rule out MOND if the orbital pole precession can be determined to an accuracy of the order of ±1°.