Excitation of neutron star oscillations by an orbiting particle

The excitation of neutron stars is expected to be an important source of gravitational radiation. Therefore it is of fundamental importance to investigate mechanisms that trigger oscillations in neutron stars in order to characterize the emitted radiation. We present results from a numerical study of the even-parity gravitational radiation generated from a particle orbiting a neutron star. In contrast to previous calculations performed in the Fourier domain, we use the direct time evolution of the perturbation equations. We focus our investigation on those conditions on the orbital parameters that favor the excitation of w-modes. We find that for astrophysically realistic conditions, there is practically no ir-mode contribution to the emitted radiation. Only for particles with ultrarelativistic orbital speeds ≥0.9c does the w-mode significantly contribute to the total emitted gravitational energy. We also stress the importance of setting consistent initial configurations. ©2001 The American Physical Society