Upper Limits on a Stochastic Background of Gravitational Waves

The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of ${\Omega }_0<8.4\times {10}^{-4}$ in the 69–156 Hz band is $\sim {10}^5$ times lower than the previous result in this frequency range.