Upper limit map of a background of gravitational waves
Abstract
We searched for an anisotropic background of gravitational waves using data from the LIGO S4 science run and a method that is optimized for point sources. This is appropriate if, for example, the gravitational wave background is dominated by a small number of distinct astrophysical sources. No signal was seen. Upper limit maps were produced assuming two different power laws for the source strain power spectrum. For an f-3 power law and using the 50 Hz to 1.8 kHz band the upper limits on the source strain power spectrum vary between 1.2×10-48Hz-1 (100Hz/f)3 and 1.2×10-47Hz-1 (100Hz/f)3, depending on the position in the sky. Similarly, in the case of constant strain power spectrum, the upper limits vary between 8.5×10-49Hz-1 and 6.1×10-48Hz-1. As a side product a limit on an isotropic background of gravitational waves was also obtained. All limits are at the 90% confidence level. Finally, as an application, we focused on the direction of Sco-X1, the brightest low-mass x-ray binary. We compare the upper limit on strain amplitude obtained by this method to expectations based on the x-ray flux from Sco-X1.
- Publication:
-
Physical Review D
- Pub Date:
- October 2007
- DOI:
- 10.1103/PhysRevD.76.082003
- arXiv:
- arXiv:astro-ph/0703234
- Bibcode:
- 2007PhRvD..76h2003A
- Keywords:
-
- 04.80.Nn;
- 02.50.Ey;
- 04.30.Db;
- 07.05.Kf;
- Gravitational wave detectors and experiments;
- Stochastic processes;
- Wave generation and sources;
- Data analysis: algorithms and implementation;
- data management;
- Astrophysics;
- General Relativity and Quantum Cosmology
- E-Print:
- 11 pages, 9 figures, 2 tables