Upper Limits on the Stochastic Gravitational-Wave Background from Advanced LIGO's First Observing Run

B. P. Abbott, California Institute of Technology
R. Abbott, Complesso Universitario di Monte sant'Angelo
T. D. Abbott, Louisiana State University
M. R. Abernathy, American University Washington DC
F. Acernese, University of Salerno
K. Ackley, University of Florida
C. Adams, Universite de Savoie
T. Adams, University of Sannio
P. Addesso, Max Planck Institute for Gravitational Physics (Albert Einstein Institute)
R. X. Adhikari, National Institute for Subatomic Physics
V. B. Adya, Massachusetts Institute of Technology
C. Affeldt, National Institute for Space Research
M. Agathos, National Institute for Nuclear Physics
K. Agatsuma, Inter-University Centre for Astronomy and Astrophysics India
N. Aggarwal, Tata Institute of Fundamental Research
O. D. Aguiar, University of Wisconsin-Milwaukee
L. Aiello, Leibniz University Hannover
A. Ain, University of Pisa
P. Ajith, Sezione di Pisa
B. Allen, Australian National University
A. Allocca, California State University Fullerton
P. A. Altin, ComUE Paris-Saclay
A. Ananyeva, Chennai Mathematical Institute
S. B. Anderson, University of Rome Tor Vergata
W. G. Anderson, University of Hamburg
S. Appert, Universite Paris 7
K. Arai, West Virginia University
M. C. Araya, University of Perugia
J. S. Areeda, European Gravitational Observatory
N. Arnaud, Syracuse University

Abstract

A wide variety of astrophysical and cosmological sources are expected to contribute to a stochastic gravitational-wave background. Following the observations of GW150914 and GW151226, the rate and mass of coalescing binary black holes appear to be greater than many previous expectations. As a result, the stochastic background from unresolved compact binary coalescences is expected to be particularly loud. We perform a search for the isotropic stochastic gravitational-wave background using data from Advanced Laser Interferometer Gravitational Wave Observatory's (aLIGO) first observing run. The data display no evidence of a stochastic gravitational-wave signal. We constrain the dimensionless energy density of gravitational waves to be Ω0<1.7×10-7 with 95% confidence, assuming a flat energy density spectrum in the most sensitive part of the LIGO band (20-86 Hz). This is a factor of ∼33 times more sensitive than previous measurements. We also constrain arbitrary power-law spectra. Finally, we investigate the implications of this search for the background of binary black holes using an astrophysical model for the background.