A tapering window for time-domain templates and simulated signals in the detection of gravitational waves from coalescing compact binaries

Inspiral signals from binary black holes, in particular those with masses in the range 10M_\odot \mathrel { \rlap{\raise0.511ex \<}{\lower0.511ex \\sim }}M \mathrel { \rlap{\raise0.511ex \<}{\lower0.511ex \\sim }}1000 M_\odot, may last for only a few cycles within a detector's most sensitive frequency band. The spectrum of a square-windowed time-domain signal could contain unwanted power that can cause problems in gravitational wave data analysis, particularly when the waveforms are of short duration. There may be leakage of power into frequency bins where no such power is expected, causing an excess of false alarms. We present a method of tapering the time-domain waveforms that significantly reduces unwanted leakage of power, leading to a spectrum that agrees very well with that of a long duration signal. Our tapered window also decreases the false alarms caused by instrumental and environmental transients that are picked up by templates with spurious signal power. The suppression of background is an important goal in noise-dominated searches and can lead to an improvement in the detection efficiency of the search algorithms.