Results from high-frequency all-sky search for continuous gravitational waves from small-ellipticity sources

We present the results of an all-sky search for continuous gravitational wave signals with frequencies in the 1700-2000 Hz range from neutron stars with ellipticity of approximate to 10(-8). The search employs the Falcon analysis pipeline [V. Dergachev and M. A. Papa, Phys. Rev. Lett. 123, 101101 (2019)] on LIGO O2 public data. Our results improve by a factor greater than 5 over [B. P. Abbott et al. (LIGO Scientific and Virgo Collaborations), Phys. Rev. D 100, 024004 (2019)]. This is a huge leap forward: it takes an entirely new generation of gravitational wave detectors to achieve a 10-fold sensitivity increase over the previous generation [D. Reitze et al., Bull. Am. Astron. Soc. 51, 035 (2019)]. Within the probed frequency range and aside from the detected outliers, we can exclude neutron stars with ellipticity of 10(-8) within 65 pc of Earth. We set upper limits on the gravitational wave amplitude that holds even for worst-case signal parameters. New outliers are found, some of which we are unable to associate with any instrumental cause. If any were associated with a rotating neutron star, this would likely be the fastest neutron star today.