On the orbital velocity of isolated galaxy pairs: II accurate MOND predictions

Abstract

Examining a catalogue of isolated galaxy pairs, a preferred orbital intervelocity of ∼150 km s-1 was recently reported. This discovery is difficult to reconcile with the expectations from Newtonian numerical simulations of cosmological structure formations. In a previous paper, we have shown that a preferred intervelocity for galaxy pairs is expected in Modified Newtonian Dynamics (MOND). Here a detailed analysis of the MOND predictions is presented, showing that a remarkable agreement with the observations can be achieved for a mass-to-light ratio M/L∼1 in solar units. This agrees with the expectations for a typical stellar population, without requiring non-baryonic dark matter for these systems.