Results from an Einstein@Home search for continuous gravitational waves from G347.3 at low frequencies in LIGO O2 data

We present results of a search for periodic gravitational wave signals with frequency between 20 and 400 Hz, from the neutron star in the supernova remnant G347.3-0.5, using LIGO O2 public data. The search is deployed on the volunteer computing project Einstein@Home, with thousands of participants donating compute cycles to make this endevour possible. We find no significant signal candidate and set the most constraining upper limits to date on the amplitude of gravitational wave signals from the target, corresponding to deformations below $10^{-6}$ in a large part of the band. At the frequency of best strain sensitivity, near $166$ Hz, we set 90% confidence upper limits on the gravitational wave intrinsic amplitude of $h_0^{90\%}\approx 7.0\times10^{-26}$. Over most of the frequency range our upper limits are a factor of 20 smaller than the indirect age-based upper limit.