First all-sky upper limits from LIGO on the strength of periodic gravitational waves using the Hough transform

TL;DR

This paper presents the first all-sky search for continuous gravitational waves using LIGO data and the Hough transform, setting upper limits on wave strength across a broad frequency range.

Contribution

It introduces a semi-coherent Hough transform method for wide parameter space searches of continuous gravitational waves from neutron stars.

Findings

Established upper limits on gravitational wave strain amplitude in 200-400 Hz range.

Demonstrated the effectiveness of the Hough transform in large-scale gravitational wave searches.

Provided the most stringent upper limits to date for unknown neutron stars in the searched frequency band.

Abstract

We perform a wide parameter space search for continuous gravitational waves over the whole sky and over a large range of values of the frequency and the first spin-down parameter. Our search method is based on the Hough transform, which is a semi-coherent, computationally efficient, and robust pattern recognition technique. We apply this technique to data from the second science run of the LIGO detectors and our final results are all-sky upper limits on the strength of gravitational waves emitted by unknown isolated spinning neutron stars on a set of narrow frequency bands in the range 200-$400 $Hz. The best upper limit on the gravitational wave strain amplitude that we obtain in this frequency range is $4.43\times 10^{-23}$.