Application of a Hough search for continuous gravitational waves on data from the fifth LIGO science run

We report on an all–sky search for periodic gravitational waves inthe frequency range 50 − 1000 Hz with the first derivative of frequency in therange −8.9 × 10−10 Hz/s to zero in two years of data collected during LIGO’sfifth science run. Our results employ a Hough transform technique, introducinga χ2 test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strainsensitivity with compute cycles per data sample compared to previously publishedsearches. Since our search yields no surviving candidates, we present resultstaking the form of frequency dependent, 95% confidence upper limits on thestrain amplitude h0. The most stringent upper limit from year 1 is 1.0 × 10−24 in the 158.00 − 158.25 Hz band. In year 2, the most stringent upper limit is 8.9 × 10−25 in the 146.50 − 146.75 Hz band. This improved detection pipeline,which is computationally efficient by at least two orders of magnitude better thanour flagship Einstein@Home search, will be important for “quick-look” searchesin the Advanced LIGO and Virgo detector era.