Search for gravitational waves from five low mass x-ray binaries in the second Advanced LIGO observing run with an improved hidden Markov model

Low mass x-ray binaries are prime targets for continuous gravitational wave searches by ground-based interferometers. Results are presented from a search for five low-mass x-ray binaries whose spin frequencies and orbital elements are measured accurately from x-ray pulsations: HETE J1900.1-2455, IGR J 00291 +5934 , SAX J1808.4-3658, XTE J0929-314, and XTE J1814-338. Data are analysed from Observing Run 2 of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). The search algorithm uses a hidden Markov model to track spin wandering, the J -statistic maximum likelihood matched filter to track orbital phase, and a suite of five vetoes to reject artefacts from non-Gaussian noise. The search yields a number of low-significance, above threshold candidates consistent with the selected false-alarm probability. The candidates will be followed up in subsequent observing runs.