An Einstein@home search for continuous gravitational waves from Cassiopeia A

TL;DR

This paper reports a comprehensive search for continuous gravitational waves from Cassiopeia A using LIGO data and Einstein@Home, setting the most stringent upper limits to date and constraining neutron star properties.

Contribution

First directed search for continuous gravitational waves from Cas A using Einstein@Home, providing the most restrictive upper limits and improving previous constraints.

Findings

No significant gravitational wave signals detected.

Set upper limits on gravitational wave amplitude around 2.9×10^{-25} at 170 Hz.

Excluded ellipticities greater than 10^{-5} above 300 Hz.

Abstract

We report the results of a directed search for continuous gravitational-wave emission in a broad frequency range (between 50 and 1000 Hz) from the central compact object of the supernova remnant Cassiopeia A (Cas A). The data comes from the sixth science run of LIGO and the search is performed on the volunteer distributed computing network Einstein@Home. We find no significant signal candidate, and set the most constraining upper limits to date on the gravitational-wave emission from Cas A, which beat the indirect age-based upper limit across the entire search range. At around 170 Hz (the most sensitive frequency range), we set 90% confidence upper limits on the gravitational wave amplitude $h_0$ of $\sim\!\!~2.9\times 10^{-25}$, roughly twice as constraining as the upper limits from previous searches on Cas A. The upper limits can also be expressed as constraints on the ellipticity of Cas A; with a few reasonable assumptions, we show that at gravitational-wave frequencies greater than 300~Hz, we can exclude an ellipticity of $\gtrsim\!\!~10^{-5}$.