2016ApJ...832L...8M

Crater II is an unusual object among the dwarf satellite galaxies of the Local Group in that it has a very large size for its small luminosity. This provides a strong test of MOND, as Crater II should be in the deep MOND regime (g_in ≃ 34 km² s^–2 kpc^–1 ≪ a₀ = 3700 km² s^–2 kpc^–1). Despite its great distance (≃120 kpc) from the Milky Way, the external field of the host (g_ex ≃ 282 km² s^–2 kpc^–1) comfortably exceeds the internal field. Consequently, Crater II should be subject to the external field effect, a feature unique to MOND. This leads to the prediction of a very low velocity dispersion: σ_efe=2.1_–0.6^+0.9 km s^–1.