Bright transients from strongly-magnetized neutron star-black hole mergers

Abstract

Direct detection of black hole-neutron star pairs is anticipated with the advent of aLIGO. Electromagnetic counterparts may be crucial for a confident gravitational-wave detection as well as for extraction of astronomical information. Yet black hole-neutron star pairs are notoriously dark and so inaccessible to telescopes. Contrary to this expectation, a bright electromagnetic transient can occur in the final moments before merger as long as the neutron star is highly magnetized. The orbital motion of the neutron star magnet creates a Faraday flux and corresponding power available for luminosity. A spectrum of curvature radiation ramps up until the rapid injection of energy ignites a fireball, which would appear as an energetic blackbody peaking in the x ray to γ rays for neutron star field strengths ranging from 10 12 G to 10 16 G respectively and a 10M black hole. The fireball event may last from a few milliseconds to a few seconds depending on the neutron star magnetic-field strength, and may be observable with the Fermi Gamma-Ray Burst Monitor with a rate up to a few per year for neutron star field strengths 10 14 G. We also discuss a possible decaying post-merger event which could accompany this signal. As an electromagnetic counterpart to these otherwise dark pairs, the black-hole battery should be of great value to the development of multi-messenger astronomy in the era of aLIGO.

Double Neutron Star Mergers and Short Gamma-ray Bursts: Long-lasting High-energy Signatures and Remnant Dichotomy

“…If young neutron stars (including magnetars and fast-spinning pulsars) are responsible for fast radio bursts, the remnants of the low-mass NS-NS binaries could be the sources of fast radio bursts, and association with fast-cooling synchrotron nebular emission, which we studied in this work, is expected. Pulsar-driven optical transients have been expected not only at the end of the NS-NS system (e.g., Yu et al 2013;Metzger & Piro 2014;Gao et al 2015;D'Orazio et al 2016) but also at the birth of the NS-NS system (e.g., Hotokezaka et al 2017a).…”

“…The amplification of magnetic fields also naturally occurs via magnetic field winding, shear instability, and magneto-rotational instability (Price & Rosswog 2006;Zrake & MacFadyen 2013;Kiuchi et al 2015;Kiuchi et al 2017). Although the formation of ordered magnetic fields (e.g., via the dynamo mechanism; Duncan & Thompson 1992;Giacomazzo et al 2015) is still under debate, the remnant NS may acquire a strong large-scale magnetic field with B * ∼ > 10 15 G. While the set of spin-down parameters, P i and B * , is uncertain, the phenomenological consequences of such a long-lived pulsar or magnetar have largely been investigated in various contexts, which include SGRBs, isotropic optical and X-ray counterparts of GW sources, and fast radio bursts (e.g., Dai & Lu 1998;Zhang & Mészáros 2001;Dai et al 2006;Fan & Xu 2006;Metzger et al 2008;Shibata et al 2011;Rowlinson et al 2013;Totani 2013;Yu et al 2013;Metzger & Piro 2014;Gao et al 2015;D'Orazio et al 2016;Murase et al 2017;Piro et al 2017). Assuming the formula of Gruzinov (2005) for an aligned rotator, the injection luminosity and the energy injection time are given by the spin-down luminosity and the spin-down time as…”

Electromagnetic Emission Post Spinning Black Hole Magnetized Neutron Star Mergers

“…For the electron acceleration in the BH's magnetosphere postmerger, there are some approaches such as BH's electric field, compared to the voltage drop accelerating electrons across magnetic-field lines connecting the NS to the BH premerger in McWilliams &Levin (2011) andD'Orazio et al (2016). The curvature radiation power for an electron with Lorentz factor γ is…”

“…During the period of magnetic reconnection at BH's poles and BH discharge resulting in a magnetic shock, the BZ mechanism might operate to extract the BH's rotational energy since the charged BH has created its own vicinal magnetosphere pervaded with charged particles postmerger. According to D'Orazio et al (2016), the BZ mechanism luminosity can be estimated by…”

Marketing Myopia – An Update (How Theodore Levitt Changed Our World? A Look at the Impact on Corporate Management after Five Decades)

“…With the synergy of the Amazon "umbrella", it is expected to make a significant inroad into the media subscription service industry. According to The Verge, (15)a technology news and media network, Apple Music has over 10 million paid subscribers, just about half as many paid subscribers as Spotify.…”