Astronomy Colloquium

Fast radio bursts (FRBs) are millisecond-duration flashes of coherent radio emission originating from extragalactic distances, offering a unique view into the physics of compact objects and their surrounding environments. Despite their brief and unpredictable nature, precise localizations of a small number of FRBs have already revealed a striking diversity in host galaxies, local environments, and burst properties - suggesting multiple progenitor channels linked to extreme compact objects. However, the nature of FRB sources remains one of the most exciting mysteries in astrophysics.

In this talk, I will show how combining high-precision localizations with detailed studies of FRB radio properties can disentangle their origins and probe the extreme plasma environments in which they reside. I will present new results from the now science-operational CHIME/FRB Outriggers project, which is transforming the world's most prolific FRB discovery instrument into a very long baseline interferometric array. The Outriggers have already approximately doubled the number of FRB host galaxies, with many more expected in the near future. Beyond localizations, the radio properties themselves encode key physical insights: scintillation measurements constrain the emission region to magnetospheric scales, directly informing the emission mechanism, while a declining electron column density over time observed in a repeating FRB points to an origin within an expanding supernova remnant. We are now entering a regime where large samples of FRBs have both detailed radio diagnostics and secure host-galaxy identifications, enabling a far more complete understanding of the extreme astrophysical systems that power FRBs.