Picture of a black hole

Strathclyde Open Access research that creates ripples...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of research papers by University of Strathclyde researchers, including by Strathclyde physicists involved in observing gravitational waves and black hole mergers as part of the Laser Interferometer Gravitational-Wave Observatory (LIGO) - but also other internationally significant research from the Department of Physics. Discover why Strathclyde's physics research is making ripples...

Strathprints also exposes world leading research from the Faculties of Science, Engineering, Humanities & Social Sciences, and from the Strathclyde Business School.

Discover more...

Upper limit map of a background of gravitational waves

Abbott, B. and Abbott, R. and Adhikari, R. and Agresti, J. and Ajith, P. and Allen, B. and Amin, R. and Lockerbie, N.A. (2007) Upper limit map of a background of gravitational waves. Physical Review D: Particles and Fields, 76 (8). ISSN 0556-2821

[img]
Preview
PDF (strathprints006478.pdf)
strathprints006478.pdf

Download (453kB) | Preview

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 1.2×10-48 Hz-1 (100 Hz/f)3 and 1.2×10-47 Hz-1 (100 Hz/f)3, depending on the position in the sky. Similarly, in the case of constant strain power spectrum, the upper limits vary between 8.5×10-49 Hz-1 and 6.1×10-48 Hz-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.