Authors

J. Aasi, California Institute of Technology
B. P. Abbott, California Institute of Technology
R. Abbott, California Institute of Technology
T. Abbott, Louisiana State University
M. R. Abernathy, California Institute of Technology
T. Accadia, Université Savoie Mont Blanc
F. Acernese, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
K. Ackley, University of Florida
C. Adams, LIGO Livingston
T. Adams, Cardiff University
P. Addesso, Università degli Studi di Salerno
R. X. Adhikari, California Institute of Technology
C. Affeldt, Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
M. Agathos, FOM-Institute of Subatomic Physics - NIKHEF
N. Aggarwal, Massachusetts Institute of Technology
O. D. Aguiar, Instituto Nacional de Pesquisas Espaciais
A. Ain, Inter-University Centre for Astronomy and Astrophysics India
P. Ajith, Tata Institute of Fundamental Research, Mumbai
A. Alemic, Syracuse University
B. Allen, Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
A. Allocca, Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
D. Amariutei, University of Florida
M. Andersen, Stanford University
R. Anderson, California Institute of Technology
S. B. Anderson, California Institute of Technology
W. G. Anderson, University of Wisconsin-Milwaukee
K. Arai, California Institute of Technology
M. C. Araya, California Institute of Technology
C. Arceneaux, University of Mississippi
J. Areeda, California State University, Fullerton
S. M. Aston, LIGO Livingston
P. Astone, Istituto Nazionale di Fisica Nucleare - INFN
P. Aufmuth, Gottfried Wilhelm Leibniz Universität Hannover

Document Type

Article

Publication Date

12-2-2014

Abstract

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of ΩGW(f)=Ωα(f/fref)α, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5-1726 Hz. In the frequency band of 41.5-169.25 Hz for a spectral index of α=0, we constrain the energy density of the stochastic background to be ΩGW(f)<5.6×10-6. For the 600-1000 Hz band, ΩGW(f)<0.14(f/900Hz)3, a factor of 2.5 lower than the best previously reported upper limits. We find ΩGW(f)<1.8×10-4 using a spectral index of zero for 170-600 Hz and ΩGW(f)<1.0(f/1300Hz)3 for 1000-1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the possible evidence for inflationary gravitational waves.

Publication Source (Journal or Book title)

Physical Review Letters

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