Searching for the Stochastic Gravitational-Wave Background with Advanced LIGO and Advanced Virgo
Résumé
The Advanced LIGO detectors have commenced observations with Advanced Virgo
joining in the near future. Gravitational waves from the merger of binary black
hole systems have been observed. A major goal for LIGO and Virgo will be to
detect or set limits on a stochastic background of gravitational waves. A
stochastic background of gravitational waves is expected to arise from a
superposition of a large number of unresolved cosmological and/or astrophys-ical
sources. A cosmologically produced background would carry unique signatures from
the earliest epochs in the evolution of the Universe. Similarly, an
astrophysical background would provide information about the astrophysical
sources that generated it. The observation of gravitational waves from binary
black holes implies that there will be a stochastic background from these
sources that could be observed by Advanced LIGO and Advanced Virgo in the near
future. The LIGO and Virgo search for a stochastic background should probe
interesting regions of the parameter space for numerous astrophysical and
cosmological models. Presented here is an outline of LIGO and Virgo's search
strategies for a stochastic background of gravitational waves, including the
search for gravitational wave polarizations outside of what is predicted from
general relativity. Also discussed is how global electromagnetic noise (from the
Schumann resonances) could affect this search; possible strategies to monitor
and subtract this potential source of correlated noise in a the global detector
network are explained. The results from Advanced LIGO's observing run O1 are
presented, along with the implications of the gravitational wave detections. The
future goals for Advanced LIGO and Advanced Virgo are explained.