The gravitational 'Magnus' effect
Presenting author: Rita Franco
It is well known from classical fluid dynamics that a spinning body moving in a fluid suffers a force orthogonal to its velocity and rotation axis --- it is called the Magnus effect. Recent theoretical predictions and numerical simulations have indirectly suggested, based on the effect of a spinning back hole on the surrounding matter, that a somewhat analogous effect may take place in gravity, although its magnitude and precise direction was still unclear. Starting from the rigorous equations of motion for spinning bodies in General Relativity (Mathisson-Papapetrou equations), we show that indeed such an effect takes place, it is a fundamental part of the spin-curvature force, which arises whenever, relative to the body, there is a mass/energy current non-parallel to its spin. We compute the effect explicitly for some astrophysical systems of interest.