Optimizing gravitational-wave searches for a population of coalescing binaries: intrinsic parameters

We revisit the problem of searching for gravitational waves from inspiralling compact binaries in Gaussian colored noise. If the intrinsic parameters of a quasicircular, nonprecessing binary are known, then the optimal statistic for detecting the dominant mode signal in a single interferometer is given by the well-known two-phase matched filter. However, the matched filter signal-to-noise ratio (SNR) is not in general an optimal statistic for an astrophysical population of signals, since their distribution over the intrinsic parameters will almost certainly not mirror that of noise events, which is determined by the (Fisher) information metric. Instead, the optimal statistic for a given astrophysical distribution will be the Bayes factor, which we approximate using the output of a standard template matched filter search. We then quantify the improvement in number of signals detected for various populations of nonspinning binaries: for a distribution of signals uniformly distributed in volume and with component masses distributed uniformly over the range 1 ≤ m 1 , 2 / M ⊙ ≤ 24 , ( m 1 + m 2 ) / M ⊙ ≤ 25 at fixed expected SNR, we find ≳ 20 % more signals at a false alarm threshold of 10 − 6 Hz in a single detector. The method may easily be generalized to binaries with nonprecessing spins