Ultrafast Outflows from Black Hole Mergers with a Mini-Disk

TL;DR

This paper explores the electromagnetic and neutrino signals from mini-disks around black hole mergers, predicting observable optical, radio, and high-energy emissions as potential multi-messenger counterparts.

Contribution

It introduces a model for outflows from mini-disks during black hole mergers, predicting multi-wavelength signals and neutrino emissions, expanding the scope of observable merger counterparts.

Findings

Thermal emission from outflows could be detected as fast optical transients.

External shocks produce radio synchrotron emission observable over years.

Potential high-energy neutrino and cosmic-ray signals are associated with jet components.

Abstract

Recently, the direct detection of gravitational waves from black hole (BH) mergers was announced by the Advanced LIGO Collaboration. Multi-messenger counterparts of stellar-mass BH mergers are of interest, and it had been suggested that a small disk or celestial body may be involved in the binary of two BHs. To test such possibilities, we consider the fate of a wind powered by an active mini-disk in a relatively short, super-Eddington accretion episode onto a BH with ~10-100 solar masses. We show that its thermal emission could be seen as a fast optical transient with the duration from hours to days. We also find that the coasting outflow forms external shocks due to interaction with the interstellar medium, whose synchrotron emission might be expected in the radio band on a time scale of years. Finally, we also discuss a possible jet component and the associated high-energy neutrino emission as well as ultra-high-energy cosmic-ray acceleration.