Fast evaluation of multidetector consistency for real-time gravitational wave searches

Gravitational waves searches for compact binary mergers with LIGO and Virgo are presently a two stage process. First, a gravitational wave signal is identified. Then, an exhaustive search over signal parameters is performed. The identification stage must be efficient in order to maximize the number of gravitational wave sources that are identified. Initial identification of gravitational wave signals with LIGO and Virgo happens in real-time, which requires that less than one second of computational time must be used for each second of gravitational wave data collected. In contrast, subsequent parameter estimation may require hundreds of hours of computational time to analyze the same one second of gravitational wave data. The real-time identification requirement necessitates efficient and often approximate methods for signal analysis. We describe one piece of a real-time gravitational-wave identification algorithm: an efficient method for ascertaining a signal's consistency between multiple gravitational wave detectors. This technique was used in analyses of Advanced LIGO's second observing run and Advanced Virgo's first observing run