Comprehensive All-sky Search for Periodic Gravitational Waves in the Sixth Science Run LIGO Data

TL;DR

This paper presents a comprehensive all-sky search for periodic gravitational waves in LIGO data, setting upper limits on wave strength without detecting any signals, thus constraining neutron star models.

Contribution

It extends previous searches by covering a larger parameter space and applying a Loosely Coherent pipeline to analyze sixth science run LIGO data.

Findings

No gravitational wave signals detected.

Established upper limits on strain amplitude, as low as 9.7×10⁻²⁵.

Improved constraints on neutron star properties.

Abstract

We report on a comprehensive all-sky search for periodic gravitational waves in the frequency band 100-1500 Hz and with a frequency time derivative in the range of $[-1.18, +1.00]\times 10^{-8}$ Hz/s. Such a signal could be produced by a nearby spinning and slightly non-axisymmetric isolated neutron star in our galaxy. This search uses the data from the Initial LIGO sixth science run and covers a larger parameter space with respect to any past search. A Loosely Coherent detection pipeline was applied to follow up weak outliers in both Gaussian (95% recovery rate) and non-Gaussian (75% recovery rate) bands. No gravitational wave signals were observed, and upper limits were placed on their strength. Our smallest upper limit on worst-case (linearly polarized) strain amplitude $h_0$ is ${9.7}\times 10^{-25}$ near 169 Hz, while at the high end of our frequency range we achieve a worst-case upper limit of ${5.5}\times 10^{-24}$. Both cases refer to all sky locations and entire range of frequency derivative values.