Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors
Abstract
Searches for a stochastic gravitationalwave background (SGWB) using terrestrial detectors typically involve crosscorrelating data from pairs of detectors. The sensitivity of such crosscorrelation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitationalwave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO's fifth science run. At low frequencies, 40460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitationalwave signal. However, at high frequencies, 4601000 Hz, these techniques are sufficient to set a 95% confidence level upper limit on the gravitationalwave energy density of Ω (f )<7.7 ×1 0^{4}(f /900 Hz )^{3} , which improves on the previous upper limit by a factor of ∼180 . In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.
 Publication:

Physical Review D
 Pub Date:
 January 2015
 DOI:
 10.1103/PhysRevD.91.022003
 arXiv:
 arXiv:1410.6211
 Bibcode:
 2015PhRvD..91b2003A
 Keywords:

 95.85.Sz;
 04.80.Nn;
 07.05.Kf;
 97.60.Jd;
 Gravitational radiation magnetic fields and other observations;
 Gravitational wave detectors and experiments;
 Data analysis: algorithms and implementation;
 data management;
 Neutron stars;
 General Relativity and Quantum Cosmology;
 Astrophysics  Instrumentation and Methods for Astrophysics
 EPrint:
 21 pages, 10 figures, 5 tables