Axial quasinormal modes of scalarized neutron stars with massive self-interacting scalar field

摘要

We study the axial quasinormal modes of neutron stars in scalar-tensor theories with a massive scalar field including a self-interacting term in the potential. Various realistic equations of state including nuclear, hyperonic, and hybrid matter are employed. Although the effect of spontaneous scalarization of neutron stars can be very large, binary pulsar observations and gravitational wave detections significantly constrain the massless scalar-tensor theories. If we consider a properly chosen nonzero mass for the scalar field, though, the scalar-tensor parameters cannot be restricted by the observations, resulting in a large deviation from pure general relativity. With this motivation in mind, we extend the universal relations for axial quasinormal modes known in general relativity to neutron stars in massive scalar-tensor theories with selfinteraction using a wide range of realistic equations of state. We confirm the universality of the scaled frequency and damping time in terms of the compactness and scaled moment of inertia for neutron stars with and without massive scalarization.