Directed search for continuous gravitational-wave signals from the Galactic Center in the Advanced LIGO second observing run

In this work we present the results of a search for continuous gravitational waves from the Galactic Center using LIGO O2 data. The search uses the band-sampled-data directed search pipeline, which performs a semicoherent wide-parameter-space search, exploiting the robustness of the FrequencyHough transform algorithm. The search targets signals emitted by isolated asymmetric spinning neutron stars, located within 25-150 parsecs from the Galactic Center. The frequencies covered in this search range between 10 and 710 Hz with a spin-down range from -1.8 x 10(-9) to 3.7 x 10(-11) Hz/s. No continuous wave signal has been detected and upper limits on the gravitational wave amplitude are presented. The most stringent upper limit at 95% confidence level, for the Livingston detector, is similar to 1.4 x 10(-25) at frequencies near 160 Hz. To date, this is the most sensitive directed search for continuous gravitational-wave signals from the Galactic Center and the first search of this kind using the LIGO second observing run.