Strain Histograms for Evaluating Continuous Gravitational Wave Candidates

Following the recent discoveries of gravitational waves from compact binary mergers, searches are under way in Advanced LIGO and Virgo data for continuous gravitational radiation emanating from rapidly spinning neutron stars. Continuous wave (CW) search algorithms often yield outlier candidates of non-astrophysical origin due to instrumental and environmental artifacts across one or both detectors. Strain histograms in the detector reference-frame frequency space permit visual assessment of outlier contamination from artifacts via superposition of the putative signal contribution on a background estimated from interpolation between neighboring spectral bands. Signal strain histograms can be constructed from computationally expensive simulations or from more rapid approximation methods. The development of a program for histogram generation using both exact and approximate simulation methods will be presented, with examples shown from CW searches in Advanced LIGO data.