Mergers of Charged Black Holes: Gravitational-Wave Events, Short Gamma-Ray Bursts, and Fast Radio Bursts

Abstract

The discoveries of GW 150914, GW 151226, and LVT 151012 suggest that double black hole (BH-BH) mergers are common in the universe. If at least one of the two merging black holes carries certain amount of charge, possibly retained by a rotating magnetosphere, the inspiral of a BH-BH system would drive a global magnetic dipole normal to the orbital plane. The rapidly evolving magnetic moment during the merging process would drive a Poynting flux with an increasing wind power. The magnetospheric activities during the final phase of the merger would make a fast radio burst (FRB) if the BH charge can be as large as a factor ofq ∼ (10 −9 − 10 −8 ) of the critical charge Q c of the BH. At large radii, dissipation of the Poynting flux energy in the outflow would power a short duration high-energy transient, which would appear as a detectable short-duration gamma-ray burst (GRB) if the charge can be as large asq ∼ (10 −5 − 10 −4 ). The putative short GRB coincident with GW 150914 recorded by Fermi GBM may be interpreted with this model. Future joint GW/GRB/FRB searches would lead to a measurement or place a constraint on the charges carried by isolate black holes.

Search for the signatures of a new-born black hole from the collapse of a supra-massive millisecond magnetar in short GRB light curves

“…Recently, Nathanail, Most & Rezzolla (2017) showed that the collapse of a rotating magnetized NS would leave behind a charged spinning (Kerr-Newman) BH. Such a charged BH was also proposed by Zhang (2016) as a product of BH-BH mergers, of which at least one carries a certain amount of charge (see also Liebling & Palenzuela 2016). In our study, if the product of collapsing supra-massive NS is a Kerr-Newman BH, then the BZ power can be provided by the BH itself even if there is no fall-back accretion.…”

Prompt electromagnetic transients from binary black hole mergers

“…Fermi found a sub-threshold gamma-ray source in a region of the sky that overlapped the ∼600-square-degree LIGO uncertainty region for GW150914 [3]. Though it may be impossible to confirm that the events are indeed physically related, the EM observation has inspired a number of papers exploring potential scenarios linking EM counterparts to stellar-mass black hole mergers [4][5][6][7][8][9][10]-mergers that theorists had expected to be electromagnetically dark.…”

Searching for Magnetar-powered Merger-novae from Short GRBS

“…Whether a BH-BH merger system could have an EM counterpart still needs further observations (see a tentative candidate GW150914-GBM claimed by the Fermi/GBM team (Connaughton et al 2016) and counter opinions (Xiong 2016;Greiner et al 2016); and some theoretical models (Zhang 2016;Loeb 2016;Perna et al 2016) and counter opinions ). GW signals from NS-NS and NS-BH mergers, on the other hand, are highly expected to be associated with EM signals (e.g.…”