Fig. 1: A side-on view of Andromeda’s asymmetrical satellite distribution.
From: Andromeda’s asymmetric satellite system as a challenge to cold dark matter cosmology
Figure constructed using data from ref. 18. Satellites are projected onto the X–Z plane of our adopted M31-centric coordinate system19—the positive X axis has the same azimuth (l = 0°) as the Milky Way (MW) and the positive Z axis points to M31’s north galactic pole. The shaded dark grey circle represents the position of M31. Satellites are coloured by their angular separation from the Milky Way as seen from M31’s expected position and the corresponding Monte Carlo uncertainties are drawn in black. The dashed circle encompasses M31’s virial radius of 266 kpc (ref. 28) and the shaded sector within represents a two-dimensional projection of the angular region within 106.5° of the Milky Way, in which all but one of M31’s 37 satellites are contained.
