Filtering post-Newtonian gravitational waves from coalescing binaries

Gravitational waves from inspiralling binaries are expected to be detected using a data analysis technique known as matched filtering. This technique is applicable whenever the form of the signal is known accurately. Though we know the form of the signal precisely, we will not know a priori its parameters. Hence it is essential to filter the raw output through a host of search templates each corresponding to different values of the parameters. The number of search templates needed in detecting the Newtonian waveform characterized by three independent parameters is itself several thousands. With the inclusion of post-Newtonian corrections the inspiral waveform will have four independent parameters and this, it was thought, would lead to an increase in the number of filters by several orders of magnitude—an unfavorable feature since it would drastically slow down data analysis. In this Rapid Communication I show that by a judicious choice of signal parameters we can work, even when the first post-Newtonian corrections are included, with as many number of parameters as in the Newtonian case. In other words I demonstrate that the effective dimensionality of the signal parameter space does not change when first post-Newtonian corrections are taken into account.