Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data
Abstract
We present the results of a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using data from the first Advanced LIGO observing run. The search method uses details of the modeled, parametrized continuous signal to combine coherently data separated by less than a specified coherence time, which can be adjusted to trade off sensitivity against computational cost. A search was conducted over the frequency range 25-2000 {Hz}, spanning the current observationally constrained range of binary orbital parameters. No significant detection candidates were found, and frequency-dependent upper limits were set using a combination of sensitivity estimates and simulated signal injections. The most stringent upper limit was set at 175 {Hz}, with comparable limits set across the most sensitive frequency range from 100 to 200 {Hz}. At this frequency, the 95% upper limit on the signal amplitude h 0 is 2.3× {10}-25 marginalized over the unknown inclination angle of the neutron star’s spin, and 8.0× {10}-26 assuming the best orientation (which results in circularly polarized gravitational waves). These limits are a factor of 3-4 stronger than those set by other analyses of the same data, and a factor of ∼7 stronger than the best upper limits set using data from Initial LIGO science runs. In the vicinity of 100 {Hz}, the limits are a factor of between 1.2 and 3.5 above the predictions of the torque balance model, depending on the inclination angle; if the most likely inclination angle of 44° is assumed, they are within a factor of 1.7.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2017
- DOI:
- 10.3847/1538-4357/aa86f0
- arXiv:
- arXiv:1706.03119
- Bibcode:
- 2017ApJ...847...47A
- Keywords:
-
- accretion;
- accretion disks;
- gravitational waves;
- stars: neutron;
- X-rays: binaries;
- Astrophysics - High Energy Astrophysical Phenomena;
- General Relativity and Quantum Cosmology
- E-Print:
- 19 pages, 8 figures. Formatted with AASTeX 6.1. Published in The Astrophysical Journal