Time-domain analysis of a dynamically tuned signal recycled interferometer for the detection of chirp gravitational waves from coalescing compact binaries

Abstract

In this article we study a particular method of detection of chirp signals from coalescing compact binary stars -- the so-called dynamical tuning, i.e. amplification of the signal via tracking of its instantaneous frequency by the tuning of the signal-recycled detector. A time-domain consideration developed for signal-recycled interferometers, in particular GEO 600, describes the signal and noise evolution in the non-stationary detector. Its non-stationarity is caused by motion of the signal recycling mirror, whose position defines the tuning of the detector. We prove that the shot noise from the dark port and optical losses remains white. The analysis of the transient effects shows that during the perfect tracking of the chirp frequency only transients from amplitude changes arise. The signal-to-noise-ratio gain, calculated in this paper, is ~ 16 for a shot-noise limited detector and ~ 4 for a detector with thermal noise.