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Title: Probing the early and late Universe with the gravitational-wave background

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Abstract: In the new era of gravitational-wave (GW) astronomy, one of the most exciting observational targets is the stochastic GW background (SGWB) — a persistent all-sky signal, sourced by incoherent GWs from many independent sources throughout cosmic history.
The SGWB is particularly sensitive to cosmic strings: line-like topological defects formed at extreme energy scales in the early Universe, which probe far beyond the reach of collider experiments. I will discuss the GW signals associated with cosmic strings, and their detection prospects with LIGO/Virgo and LISA.
Another important signal at late times is the astrophysical GW background (AGWB) generated by the superposition of many compact binary coalescences. These binaries are tracers of the galaxy distribution, and therefore offer a novel probe of large-scale structure. I will present calculations of the AGWB’s angular spectrum using large N-body simulations, and discuss optimal statistical methods for estimating the spectrum from GW data.

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