ON THE SUPERSTRING AXION MINI-STAR

Abstract

The theory of the pressure-free-boson mini-star of mass M, whose radius r=2GM/v2 is equated via the indeterminacy principle to ℏ/mv, where [Formula: see text] is the Newton gravitational constant, M P being the Planck mass and m the mass of the boson, travelling at velocity v, is applied to the superstring axion. For a bounded object, the upper limit to the axion potential [Formula: see text] constrains the axions to move at non-relativistic velocities [Formula: see text] where [Formula: see text] GeV is the axion decay constant, predicting the existence of an axion mini-star of mass [Formula: see text]. Such objects can in principle form by gravitational collapse below the temperature T≈100 eV, and are tentatively identified with the microlensing objects recently detected in our Galaxy and in the direction of the Large Magellanic Cloud.