Loosely coherent search in LIGO O1 data for continuous gravitational waves from Terzan 5 and the Galactic Center

We report results of a search for continuous gravitational waves from a region covering the globular cluster Terzan 5 and the Galactic Center. Continuous gravitational waves are expected from fast-spinning, slightly nonaxisymmetric isolated neutron stars as well as more exotic objects. The regions that we target are believed to be unusually abundant in neutron stars. We use a new loosely coherent search method that allows one to reach unprecedented levels of sensitivity for this type of search. The search covers the frequency band 475-1500 Hz and frequency time derivatives in the range of [-3.0, +0.1] x 10(-8) Hz/s, which is a parameter range not explored before with the depth reached by this search. As to be expected with only a few months of data from the same observing run, it is very difficult to make a confident detection of a continuous signal over such a large parameter space. A list of parameter space points that passed all the thresholds of this search is provided. We follow up the most significant outlier on the newly released O2 data and cannot confirm it. We provide upper limits on the gravitational wave strength of signals as a function of signal frequency.