# Loosely coherent search in LIGO O1 data for continuous gravitational waves from Terzan 5 and the galactic center

## TL;DR

This paper presents a new sensitive search for continuous gravitational waves from neutron stars in the Terzan 5 cluster and galactic center using LIGO O1 data, setting upper limits on wave strength.

## Contribution

Introduces a novel loosely coherent search method enabling unprecedented sensitivity in a previously unexplored parameter space for continuous gravitational waves.

## Key findings

- No confident detection of continuous signals was made.
- A list of promising parameter space points is provided.
- Upper limits on gravitational wave strength are established.

## Abstract

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 non-axisymmetric 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 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 [-3e-8, +1e-9] 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.