| Source: |
Physical review. D, Particles, fields, gravitation, and cosmology 76 (2007): 082003. doi:10.1103/PhysRevD.76.082003 ; info:cnr-pdr/source/autori:B. Abbott (14) , R. Abbott (14) , R. Adhikari (14) , J. Agresti (14) , P. Ajith (2) , B. Allen (2) , (51) , R. Amin (18) , S. B. Anderson (14) , W. G. Anderson (51) , M. Arain (39) , M. Araya (14) , H. Armandula (14) , M. Ashley (4) , S. Aston (38) , P. Aufmuth (36) , C. Aulbert (1) , S. Babak (1) , S. Ballmer (14) , H. Bantilan (8) , B. C. Barish (14) , C. .... |
| Description: |
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 x 10(-48) Hz(-1) (100 Hz/f)(3) and 1.2 x 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 x 10(-49) Hz(-1) and 6.1 x 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. |