Fast Radio Bursts and Radio Transients from Black Hole Batteries
Most black holes (BHs) will absorb a neutron star (NS) companion fully intact without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic (EM) luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally, the luminosity was expected to be in high-energy X-rays or gamma-rays, however, we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs; millisecond-scale radio transients) NS–BH coalescence rates are too low to make these a primary FRB source. Instead, we propose that the transients form a FRB sub-population, distinguishable by a double peak with a precursor. The rapid ramp-up in luminosity manifests as a precursor to the burst which is 20%–80% as luminous given 0.5 ms timing resolution. The main burst arises from the peak luminosity before the merger. The post-merger burst follows from the NS magnetic field migration to the BH, causing a shock. NS–BH pairs are especially desirable for ground-based gravitational wave (GW) observatories since the pair might not otherwise be detected, with EM counterparts greatly augmenting the scientific leverage beyond the GW signal. The EM signal's ability to break degeneracies in the parameters encoded in the GW and probe the NS magnetic field strength is quite valuable, yielding insights into open problems in NS magnetic field decay.
© 2015 The American Astronomical Society. Received 2015 September 23; accepted 2015 November 9; published 2015 November 23. We thank the referee, M. Vallisneri, and S. Nissanke for carefully reading the manuscript. We acknowledge valuable discussions with S. McWilliams, M. Kasliwal, D. Tsang, A. Lommen, F. Pannarale, S. Taylor, J. Ellis, J. Bell-Burnell, and P. Goldreich. C.M.F.M. was supported by a Marie Curie International Outgoing Fellowship within the European Union Seventh Framework Programme. J.L. thanks the Tow Foundation for their support. J.L. was also supported by a Guggenheim Fellowship. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. An ipython notebook which reproduces our results is available https://github.com/ChiaraMingarelli.
Submitted - 1511.02870v1.pdf
Published - Mingarelli_2015.pdf