Upper limit map of a background of gravitational waves

B Abbott, R Abbott, R Adhikari, J Agresti, P Ajith, B Allen, R Amin, SB Anderson, WG Anderson, M Arain, M Araya, H Armandula, M Ashley, S Aston, P Aufmuth, C Aulbert, S Babak, S Ballmer, H Bantilan, BC BarishPhilip Charlton

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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 the50 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.
Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number8
Publication statusPublished - 2007


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