http://arxiv.org/abs/1902.07939
The mergers of black hole (BH) — neutron star (NS) binaries have been one of the most interesting topics, because such events have been thought to possibly produce multi-messenger signals including gravitational waves and broadband electromagnetic (EM) waves. In this paper, we investigate EM emission from the inspiral of a binary composed of a rotating BH and a magnetized NS. Observationally, the BH is usually more massive than $\sim7M_\odot$ and the NS has a mass $\simeq 1.4M_\odot$. During the inspiral of such a binary, the BH will accumulate more and more charges based on the charging scenario of Wald (1974), even though the BH will eventually swallow the NS whole inevitably. We calculate the emission luminosities and energies from three energy dissipation mechanisms: magnetic dipole radiation, electric dipole radiation, and magnetic reconnection. We show that magnetic dipole radiation due to the spin of the increasingly charged BH could be most significant at the final inspiral stage. We find that if the BH is rapidly rotating and the NS is strongly magnetized, this mechanism would lead to a detectable EM signal (e.g., a short-duration X-ray and/or radio transient).
Z. Dai
Fri, 22 Feb 19
7/52
Comments: 5 pages, emulateapj.style
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