Searches for gravitational waves from known pulsars at two harmonics in the second and third LIGO-Virgo observing runs

摘要: To date, the LIGO and Virgo observatories have made detections of numerous sources of gravitational radiation. These detections have been of transient gravitational waves (GWs) from the inspiral and subsequent mergers of compact binary objects including binary black holes and binary neutron stars (Abbott et al. 2021a). Recently, the list of observed events expanded to include neutron star, black hole binaries (Abbott et al. 2021b). There remain other types of GW sources that are yet to be observed such as continuous GW (CW) sources. Unlike transients, CW signals are almost monochromatic, with their amplitude and frequency changing very slowly over yearlong timescales. The mass quadrupoles of these sources, such as deformed neutron stars, are expected to be far smaller than those involved in compact binaries, and therefore only the local galactic sources are likely to produce detectable signals. Likely …