Searching for continuous gravitational-wave emission associated with stochastic radiometer candidates

Abstract:

Continuous gravitational waves (CWs) from spinning, non-axisymmetric neutron stars can reveal novel insights into the physics of neutron star interiors, but have so far gone undetected. Searches for CWs in gravitational-wave interferometer data generally assume a phase-coherent signal over the observation period. Un-modelled methods, such as the All-Sky All-Frequency (ASAF) radiometer search for stochastic gravitational waves, may reveal CW signals which randomly wander in frequency, e.g. due to spin-up glitches or accretion torques. I will present results from a CW search of Advanced LIGO data from the third observing run (O3), which targets these ASAF sub-threshold candidates. Our search algorithm combines template-based matched filtering techniques with the Hidden Markov model (HMM) formalism, allowing the signal to undergo a random walk in frequency. We find no convincing evidence of CWs associated with the ASAF candidates in O3 data. We estimate our sensitivity by running the search on simulated signals.