Speaker
Description
Cosmic strings were once considered a leading candidate for the origin of cosmic structure, but high-resolution measurements of the cosmic microwave background (CMB) have ruled them out as the primary source of density fluctuations. Nevertheless, there remains ample room within the ΛCDM framework for the existence of cosmic strings or superstrings at subdominant levels. As these networks evolve, they generate loops that may decay via gravitational-wave emission, producing a stochastic gravitational-wave background (SGWB). In this talk, I will review the state-of-the-art modelling of cosmic and superstring network evolution and their predicted CMB and GW signatures. I will then present recent constraints and search results for cosmic (super)strings from NANOGrav pulsar-timing data and Atacama Cosmology Telescope (ACT) CMB observations.