Hunting continuous gravitational waves from binary neutron stars
AEI researchers develop and conduct most sensitive search to date
In addition to the well-known gravitational waves from merging black-hole or neutron-star binaries, astronomers expect different signals from other sources. A prime candidate are continuous gravitational waves emitted by rapidly rotating non-axisymetrically deformed neutron stars. If the neutron stars are in binary systems, the search for their weak but persistent gravitational waves is computationally very demanding. At the same time, they are very promising targets because the companion star could induce the necessary deformations of the neutron star. A team from the permanent independent research group “Continuous Gravitational Waves” at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Hannover has now published a study on their novel search in public LIGO data for gravitational waves from unknown neutron stars in binary systems with long orbital periods (between 100 days and 1000 days). The signals from the neutron stars in the orbits targeted now have never been directly searched for before. Their new search of the entire sky is the most sensitive yet.
Paper abstract
Gravitational waves emitted by asymmetric rotating neutron stars are the primary targets of continuous gravitational-wave searches. Neutron stars in binary systems are particularly interesting due to the potential for non-axisymmetric deformations induced by a companion star. However, all-sky searches for unknown neutron stars in binary systems are very computationally expensive and this limits their sensitivity and/or breadth. In this paper we present results of a search for signals with gravitational-wave frequencies between 50 and 150 Hz, from systems with orbital periods between 100 and 1000 days and projected semi-major axes between 40 and 200 light-seconds. This parameter-space region has never been directly searched before. We do not detect any signal, and our results exclude gravitational-wave amplitudes above 1.25×10−25 at 144.32 Hz with 95% confidence. Our improved search pipeline is more sensitive than any previous all-sky binary search by about 75%
