Gravitational Radiation during Thorne-Zytkow object formation

Abstract

Calculation of gravitational radiation during binary inspiral leading to possible formation of a Thorne-Zytkow (TZ) object (a neutron star inside a supergiant core) is performed. The calculations were done for polytropic density distributions with different indeces $n$, as well as for realistic models of supergiants. A maximum frequency of the emitted gravitational waves during this process was found to range from a few to 300 initial keplerian orbital frequensies, that is from $10^{-5}$ to $\sim 0.1$ Hz, depending on the model. A dimensionless strain metric amplitude can reach $h\sim 10^{-23.5}$ for a source lying 10 kpc away from the Sun. We conclude that TZ objects forming at a rate of 1 per 500 yrs in the Galaxy could be potential astrophysical targets for space laser intereferometers. Analysis of gravitational waveforms emitted during TZ-object formation could bring a unique information about stellar structure.