Searches for continuous gravitational waves from nine young supernova remnants

TL;DR

This study conducted targeted searches for continuous gravitational waves from nine young supernova remnants using LIGO data, setting upper limits on gravitational wave strain, ellipticity, and r-mode amplitude, but found no signals.

Contribution

First directed search for continuous gravitational waves from these nine young supernova remnants, improving upper limits and testing theoretical models.

Findings

No credible gravitational-wave signals detected.

Set the most stringent upper limits to date on strain and neutron star properties.

Results are within the range of theoretical predictions.

Abstract

We describe directed searches for continuous gravitational waves in data from the sixth LIGO science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of ten. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering F-statistic. We found no credible gravitational-wave signals. We set 95% confidence upper limits as strong (low) as $4\times10^{-25}$ on intrinsic strain, $2\times10^{-7}$ on fiducial ellipticity, and $3\times10^{-6}$ on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.