Electromagnetic emission from axionic boson star collisions

Understand

We explore the dynamics of boson stars in the presence of axionic couplings through nonlinear evolutions of Einstein's field equations.

• We show that, for large axionic couplings, isolated boson stars become unstable, and decay via a large burst of electromagnetic radiation, becoming less massive and more dilute.
• Our full nonlinear results are in good agreement with flat-space estimates for the critical couplings.
• We then consider head-on collisions of sub-critical boson stars and study the electromagnetic and gravitational signal.