TY - JOUR

T1 - Upper limit map of a background of gravitational waves

AU - LIGO Scientific Collaboration

AU - Pitkin, M.

PY - 2007/10/1

Y1 - 2007/10/1

N2 - 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.

AB - 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.

KW - 04.80.Nn

KW - 02.50.Ey

KW - 04.30.Db

KW - 07.05.Kf

KW - Gravitational wave detectors and experiments

KW - Stochastic processes

KW - Wave generation and sources

KW - Data analysis: algorithms and implementation

KW - data management

KW - Astrophysics

KW - General Relativity and Quantum Cosmology

U2 - 10.1103/PhysRevD.76.082003

DO - 10.1103/PhysRevD.76.082003

M3 - Journal article

VL - 76

JO - Physical Review D

JF - Physical Review D

SN - 1550-7998

IS - 8

M1 - 082003

ER -