A study of time-frequency stacking to enhance detectability of BNS postmerger gravitational wave signals

Gravitational wave signals generated by binary neutron star coalescences encode clues about the neutron star equation of state. Particularly, the postmerger component carries information about the NS EOS at higher densities than what we learn from the inspiral phase. Given the high frequency (a few kHz) and the smaller amplitude of the postmerger compared to the inspiral, the probability of confidently detecting a BNS postmerger gravitational wave signal with LIGO and Virgo detectors is low. Therefore, one approach is to combine observations to increase the detectability of the signal. Here we explore the method of stacking time-frequency maps to study the frequency content of the postmerger. We apply continuous wavelet transforms on simulated signals reconstructed by BayesWave, an unmodeled wavelet-based algorithm that can jointly detect and characterize gravitational wave transients. With the time-frequency maps for individual simulated events, we investigate how the detectability of the BNS postmerger signal changes when combining multiple T-F maps in the current and next-generation gravitational wave interferometers.