Abbott, B. and Abbott, R. and Adhikari, R. and Agresti, J. and Ajith, P. and Allen, B. and Amin, R. and Anderson, S.B. and Lockerbie, N.A. and , LIGO Sci Collaboration and , ALLEGRO Collaboration (2007) First cross-correlation analysis of interferometric and resonant-bar gravitational-wave data for stochastic backgrounds. Physical Review D: Particles and Fields, 76 (2). 022001/1-022001/17. ISSN 0556-2821
Data from the LIGO Livingston interferometer and the ALLEGRO resonant-bar detector, taken during LIGO's fourth science run, were examined for cross correlations indicative of a stochastic gravitational-wave background in the frequency range 850-950 Hz, with most of the sensitivity arising between 905 and 925 Hz. ALLEGRO was operated in three different orientations during the experiment to modulate the relative sign of gravitational-wave and environmental correlations. No statistically significant correlations were seen in any of the orientations, and the results were used to set a Bayesian 90% confidence level upper limit of Omegagw(f)<=1.02, which corresponds to a gravitational-wave strain at 915 Hz of 1.5×10-23 Hz-1/2. In the traditional units of h1002Omegagw(f), this is a limit of 0.53, 2 orders of magnitude better than the previous direct limit at these frequencies. The method was also validated with successful extraction of simulated signals injected in hardware and software.
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