Abstract
Axions and axionlike particles are a leading model for the dark matter in the Universe; therefore, dark matter halos may be boson stars in the process of collapsing. We examine a class of static boson stars with a nonminimal coupling to gravity. We modify the gravitational density of the boson field to be proportional to an arbitrary power of the modulus of the field, introducing a nonstandard coupling. We find a class of solutions very similar to Newtonian polytropic stars that we denote “quantum polytropes.” These quantum polytropes are supported by a nonlocal quantum pressure and follow an equation very similar to the Lane-Emden equation for classical polytropes. Furthermore, we derive a simple condition on the exponent of the nonlinear gravitational coupling, , beyond which the equilibrium solutions are unstable.
- Received 26 September 2017
DOI:https://doi.org/10.1103/PhysRevD.96.103010
© 2017 American Physical Society