Furthermore, Chae says that when one takes into account the external field effect – an integral part of MOND that describes how a much larger gravitational field, in this case that of the Milky Way galaxy as a whole, can affect a smaller gravitational system such as a binary star – the gravitational acceleration at wide separations is boosted by a factor of 1.4. This matches a prediction of a specific model of MOND called AQUAL, which was developed by Milgrom and the late physicist Jacob Bekenstein of the Hebrew University of Jerusalem..
“It is truly remarkable that when the external field effect is taken into account, the boost factor is about 1.4,” says Chae. “To me, this cannot be a coincidence.”