Universal relations for rotating boson stars

Boson stars represent a hypothetical exotic type of compact stellar object that may be observed from the gravitational signal of coalescing binaries in current and future gravitational wave (GW) detectors. In this work we show that the moment of inertia I, the (dimensionless) angular momentum%, and the quadrupole moment Q of rotating boson stars obey a universal relation, valid for a wide set of boson star models. Further, the obtained I - % - Q relation clearly differs from its famous neutron star counterpart, providing us with an unequivocal diagnostic tool to distinguish boson stars from ordinary compact stars or other celestial bodies in GW observations. Such universal (i.e., model-independent) relations also provide a useful tool to probe the strong gravity regime of general relativity and to constrain the equation of state of matter inside compact stars.

Automated summary

In this work, a universal relation among the moment of inertia, angular momentum, and quadrupole moment of rotating boson stars is discovered, which differs from the relation found in neutron stars. This provides a diagnostic tool to distinguish boson stars from other celestial bodies.