Einstein@Home all-sky search for periodic gravitational waves in LIGO S5 data

TL;DR

This paper reports a comprehensive all-sky search for periodic gravitational waves in LIGO S5 data using a novel non-coherent Hough-transform technique, deploying Einstein@Home's distributed computing to improve sensitivity and set upper limits.

Contribution

Introduces a new non-coherent Hough-transform method for gravitational wave searches and demonstrates its application on LIGO S5 data with enhanced sensitivity.

Findings

No gravitational wave signals detected.

Set upper limits on gravitational wave amplitude.

Search sensitivity improved by a factor of 3.

Abstract

This paper presents results of an all-sky searches for periodic gravitational waves in the frequency range [50, 1190] Hz and with frequency derivative ranges of [-2 x 10^-9, 1.1 x 10^-10] Hz/s for the fifth LIGO science run (S5). The novelty of the search lies in the use of a non-coherent technique based on the Hough-transform to combine the information from coherent searches on timescales of about one day. Because these searches are very computationally intensive, they have been deployed on the Einstein@Home distributed computing project infrastructure. The search presented here is about a factor 3 more sensitive than the previous Einstein@Home search in early S5 LIGO data. The post-processing has left us with eight surviving candidates. We show that deeper follow-up studies rule each of them out. Hence, since no statistically significant gravitational wave signals have been detected, we report upper limits on the intrinsic gravitational wave amplitude h0. For example, in the 0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h0 greater than 7.6 x 10^-25 with a 90% confidence level.