paper

Radio Nebulæ from Hyper-Accreting X-ray Binaries as Common Envelope Precursors and Persistent Counterparts of Fast Radio Bursts

arXiv:2206.10486 · doi:10.3847/1538-4357/ac8a4a

Abstract

Roche lobe overflow from a donor star onto a black hole or neutron star binary companion can evolve to a phase of unstable runaway mass-transfer, lasting as short as hundreds of orbits ( yr for a giant donor), and eventually culminating in a common envelope event. The highly super-Eddington accretion rates achieved during this brief phase ( are accompanied by intense mass-loss in disk winds, analogous but even more extreme than ultra-luminous X-ray (ULX) sources in the nearby universe. Also in analogy with observed ULX, this expanding outflow will inflate an energetic `bubble' of plasma into the circumbinary medium. Embedded within this bubble is a nebula of relativistic electrons heated at the termination shock of the faster wind/jet from the inner accretion flow. We present a time-dependent, one-zone model for the synchrotron radio emission and other observable properties of such ULX `hyper-nebulae'. If ULX jets are sources of repeating fast radio bursts (FRB), as recently proposed, such hyper-nebulae could generate persistent radio emission and contribute large and time-variable rotation measure to the bursts, consistent with those seen from FRB 20121102 and FRB 190520B. ULX hyper-nebulae can be discovered independent of an FRB association in radio surveys such as VLASS, as off-nuclear point-sources whose fluxes can evolve significantly on timescales as short as years, possibly presaging energetic transients from common envelope mergers.

arXiv comment27 pages, 9 figures, 1 table; accepted for publication in ApJ

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