Description
On the dynamical bar-mode instability of spinning bosonic stars
Abstract:We report results from three-dimensional numerical-relativity simulations of spinning bosonic stars, both considering a scalar field or a vector (Proca) field. In both cases, the bosonic field is assumed complex and massive. The scalar star is always affected by the growth of a non-axisymmetric instability which triggers the loss of angular momentum and its migration to a non-spinning boson star. For $m=1$ Proca stars, however, no such instability was observed. We tentatively related the different stability properties to the different toroidal/spheroidal topology of the scalar/Proca models. we qualitatively study the instability of SBSs through the analysis of the growth rate of azimuthal density modes and the search of a corotation point in the unstable models. This allows us to put forward a parallelism with rotating neutron stars affected by dynamical bar-mode instabilities. We compute the gravitational wave emission through the mode decomposition of the Newman-Penrose scalar. We compute the characteristic GW strain for some of our models and we compare it with the sensitivity curves of ground-based detectors, space detectors and PTAs. For the ranges of masses in the sensitivity range of each detector we compute the SNR and we evaluate the horizon distance, as the distance at which the SNR is equal to a certain threshold value.
