光学天文与技术应用研究室知识库

We investigate the stochastic foreground of gravitational waves (GWs) from ultra-compact neutron star-white dwarf (NS-WD) binaries in our Galaxy or at cosmological space. Observationally, accreting neutron stars and donor white dwarf stars form the low-mass X-ray binaries (LMXBs). Based on the luminosity function determined from X-ray observations, we study the production of NS-WDs using a binary population synthesis approach, and calculate their contribution to the Galactic GW foreground radiation. From a sample of 10(7) binaries, we calculate the evolutionary processes of these NS-WD systems between 10(-5) and 10(-2) Hz, which may be detected by the Laser Interferometer Space Antenna (LISA). We conclude that NS-WD binaries due to below the delectability level of the LISA cannot dominate the Galactic GW foreground radiation. This is because that the GW signal of NS-WD systems will be burred by that of close double white dwarf systems. We argue that several Galactic NS-WD binaries may be resolved by LISA due to the short orbital period. Meanwhile, the extragalactic foreground is unlikely to be detected.