Speaker: Julian Carlin
Search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars in O3 LIGO data
We performed a search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars, using data from the third observing run of the Advanced LIGO detector. The search algorithm uses a hidden Markov model, where the frequency is allowed to wander according to an unbiased random walk. Three narrow sub-bands are searched for each target, centered on harmonics of the measured spin frequency. The search yields 16 candidates, consistent with a false alarm probability of 30% per sub-band and target searched. These candidates, along with one candidate from an additional target-of-opportunity search done for SAX J1808.4−3658, which was in outburst during one month of the observing run, cannot be confidently associated with a known noise source. Additional follow-up does not provide convincing evidence that any are a true astrophysical signal. When all candidates are assumed non-astrophysical, we set upper limits on the maximum wave strain detectable at 95% confidence. These upper limits lead to constraints on neutron star ellipticity and r-mode amplitude. This analysis is the most comprehensive and sensitive search of continuous gravitational waves from accreting millisecond X-ray pulsars to date.
Zoom link: https://caltech.zoom.us/j/82072539167