  A detection of the stochastic gravitational-wave background (SGWB) from
unresolved compact binary coalescences could be made by Advanced LIGO and
Advanced Virgo at their design sensitivities. However, it is possible for
magnetic noise that is correlated between spatially separated ground-based
detectors to mimic a SGWB signal. In this paper we propose a new method for
detecting correlated magnetic noise and separating it from a true SGWB signal.
A commonly discussed method for addressing correlated magnetic noise is
coherent subtraction in the raw data using Wiener filtering. The method
proposed here uses a parameterized model of the magnetometer-to-strain coupling
functions, along with measurements from local magnetometers, to estimate the
contribution of correlated noise to the traditional SGWB detection statistic.
We then use Bayesian model selection to distinguish between models that include
correlated magnetic noise and those with a SGWB. Realistic simulations are used
to show that this method prevents a false SGWB detection due to correlated
magnetic noise. We also demonstrate that it can be used for a detection of a
SGWB in the presence of strong correlated magnetic noise, albeit with reduced
significance compared to the case with no correlated noise. Finally, we discuss
the advantages of using a global three-detector network for both identifying
and characterizing correlated magnetic noise.
