Presentation #116.63 in the session Stellar/Compact Objects.
Roche lobe overflow from a donor star onto a compact object binary companion can evolve to a phase of unstable runaway mass transfer, before eventually culminating in a common-envelope event. The hyper-Eddington accretion rates achieved during this brief phase are accompanied by an intense mass loss through disk winds, analogous to, but even more extreme than ultraluminous X-ray sources in the nearby universe. This expanding outflow will inflate a compact and energetic bubble of plasma into the circumbinary medium (a “hypernebula”). Embedded within this hypernebula are relativistic electrons heated at the termination shock of the winds from the inner accretion flow. We have developed a time-dependent, radiative, multi-messenger model for the X-ray, synchrotron radio, and high energy neutrino emission (100 TeV-PeV, as seen by IceCube) from hypernebulae. If episodic, relativistic jets are sources of (periodically) repeating fast radio bursts (Sridhar+21b), such hypernebulae could generate a persistent radio emission and contribute large and time-variable Faraday rotation measure to the bursts, consistent with the observations. Hypernebulae can be discovered through large area radio surveys, such as VLASS, as off-nuclear point sources. They presage energetic transients from common envelope mergers, and can act as signposts to future gravitational wave (LISA) events.