Template mode hierarchies for binary black hole mergers

Matched filtering is a popular data analysis framework used to search for gravitational wave signals emitted by compact object binaries. The templates used in matched filtering searches are constructed predominantly from the quadrupolar mode since this is the energetically most dominant mode. However, for highly precessing binaries or binaries with moderately large mass ratios, quadrupole templates lose sensitivity for a significant fraction of source orientations. We investigate how the inclusion of higher modes in the templates alleviates this loss of sensitivity and thus increases the prospects for detecting gravitational waves. Specifically, we use numerical relativity waveforms from the late inspiral and coalescence of binary black holes to identify mode hierarchies from which one can construct templates that cover the entire sky of binary orientations. The ordering in these hierarchies depends on the characteristics of the binary system and the mode strengths. The proposed hierarchies could assist in deciding which modes to add to template banks according to their ability to maximize sky coverage.