| Abstract: | Radio emission from astrophysical transients provides a unique window into the fastest outflows in the Universe, directly probing shock physics, circumstellar environments, the formation and evolution of relativistic jets, and energy injection. Connecting radio emission to observations at other wavelengths improves our understanding of explosive and accretion-powered phenomena and motivates future collaborations between time-domain radio surveys and surveys in the optical, UV, and especially X-ray bands. In this talk, I will discuss how combining radio observations with shorter-wavelength emission links different classes of transients across a wide range of timescales, focusing on core-collapse supernovae (CCSNe) and tidal disruption events (TDEs). In CCSNe, radio surveys have revealed multiple re-brightenings of decade-old supernovae, highlighting the importance of systematic monitoring of stellar explosions over long timescales. I will show how applying this approach informs us about the mass-loss histories of massive stars and, potentially, the presence of relativistic off-axis jets. In TDEs, radio emission is known to rise on a variety of timescales. I will present our discovery of the first radio-bright off-nuclear TDE and its unprecedented evolution, which challenges standard TDE models and offers a new perspective on accretion-driven outflows in non-standard black-hole environments. |