Comparison of bar and interferometer sensitivities to sources of transient gravitational radiation.

Abstract

The signal-to-noise ratios for the detection of gravitational radiation are derived and compared for resonant bar and laser interferometric detectors. The results presented here apply to the detection of transient gravitational radiation as would be emitted in particlendashblack-hole interactions, stellar collapse events, or the decay of compact binary systems. For the detection of fixed-energy gravitational-wave bursts, the bar antenna shows its resonant nature with a sensitivity that is broadly peaked near the bar frequency, while the interferometer response shows a smooth ${f}^{\mathrm{\ensuremath{-}}1}$ dependence. Applied to the detection of the radiation emitted in the decay of a compact binary system, the ratio of bar to interferometer sensitivities is independent of source parameters. Using operational antenna parameters (circa 1985), the 4.2-K Stanford bar (${T}_{d}$=20 mK, ${M}_{a}$=4.8\ifmmode\times\else\texttimes\fi{}${10}^{3}$ kg, ${L}_{a}$=3 m, ${f}_{a}$=840 Hz) is shown to be typically three times more sensitive to transient sources than the 30-m interferometer (h\ifmmode \tilde{}\else \~{}\fi{}=2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}19}$/ \ensuremath{\surd}Hz above 500 Hz) at the Max-Planck-Institut f\ur Quantenoptik in Garching, West Germany. Additionally, the signal-to-noise ratios calculated here are normalized to represent optimistic Galactic sources (located at 10 kpc, ${10}^{\mathrm{\ensuremath{-}}2}$ ${M}_{\ensuremath{\bigodot}}$${c}^{2}$ emitted in a gravitational burst) and indicate that both antennas are operating near astrophysically interesting sensitivities with signal-to-noise ratios ranging from 1 to 10 for these sources.