Searching for the isotropic gravitational-wave background with Advanced LIGO and Virgo

A target for the next gravitational-wave discovery is the gravitational-wave background (GWB) produced by a superposition of many different astrophysical and cosmological sources, including merging compact binaries, cosmic strings, and cosmic inflation. In this talk I will describe the cross-correlation-based search strategy used by the LIGO, Virgo, and Kagra collaborations, as well as how potential sources of correlated noise such as geophysical Schumann resonances can be understood and mitigated. I will present the most up-to-date constraints on an isotropic GWB, and describe implications for the GWB from compact binaries, which could potentially be within reach of the sensitivity of the advanced detector network at design sensitivity.