Effects of oscillating spacetime metric background on a complex scalar field and formation of topological vortices

TL;DR

This study investigates how oscillating spacetime metrics influence a complex scalar field, leading to vortex formation via parametric resonance, with potential implications for astrophysical phenomena and ultralight axion-like fields.

Contribution

It demonstrates the impact of oscillating spacetime backgrounds on scalar fields, revealing vortex formation mechanisms and lattice structures in high-frequency regimes through (2+1)-D simulations.

Findings

Oscillating spacetime can excite scalar fields and induce vortex formation.

Parametric resonance drives field excitations and vortex dynamics.

High-frequency oscillations lead to non-topological vortices and vortex-antivortex lattices.

Abstract

We study the time evolution of a complex scalar field in the symmetry broken phase in the presence of oscillating spacetime metric background. In our (2+1)-dimensional simulations, we show that the spacetime oscillations can excite an initial field configuration, which ultimately leads to the formation of topological vortices in the system. At late times, field configuration achieves a disordered state. A detailed study of the momentum and frequency modes of the field reveals that these field excitations are driven by the phenomenon of parametric resonance. In extremely high frequency regime where frequency of spacetime oscillations is much larger than the field-mass, the formed vortices are not topological in nature. Interestingly in this regime, for a suitable choice of parameters of the simulation, we observe a persistent lattice structure of vortex-antivortex pairs. We discuss applications of our study to the dynamics of interior superfluidity of neutron stars during binary neutron star mergers, in generation of excitation in ultralight axion-like field near a strong gravitational wave source, etc.