Cross-correlation search for continuous gravitational waves from a compact object in SNR 1987A in LIGO Science run 5

We present the results of a cross-correlation search for gravitational waves from SNR 1987A using the second year of LIGO science run 5 data. The frequency band 75-450 Hz is searched. No evidence of gravitational waves is found. A 90% confidence upper limit of h₀ ≤ 3.8 × 10^-25 is placed on the gravitational-wave strain at the most sensitive frequency near 150 Hz. This corresponds to an ellipticity of ϵ ≤ 8.2 × 10^-4 and improves on previously published strain upper limits by a factor of approximately 4. We perform a comprehensive suite of validations of the search algorithm and identify several computational savings that marginally sacrifice sensitivity in order to streamline the parameter space being searched. We estimate detection thresholds and sensitivities through Monte Carlo simulations.