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Title: Current Sheet Alignment in Oblique Black Hole Magnetospheres: A Black Hole Pulsar?
Abstract We study the magnetospheric evolution of a nonaccreting spinning black hole (BH) with an initially inclined split monopole magnetic field by means of 3D general relativistic magnetohydrodynamic simulations. This serves as a model for a neutron star (NS) collapse or a BH–NS merger remnant after the inherited magnetosphere has settled into a split monopole field creating a striped wind. We show that the initially inclined split monopolar current sheet aligns over time with the BH equatorial plane. The inclination angle evolves exponentially toward alignment, with an alignment timescale that is inversely proportional to the square of the BH angular velocity, where higher spin results in faster alignment. Furthermore, magnetic reconnection in the current sheet leads to exponential decay of event-horizon-penetrating magnetic flux with nearly the same timescale for all considered BH spins. In addition, we present relations for the BH mass and spin in terms of the period and alignment timescale of the striped wind. The explored scenario of a rotating, aligning, and reconnecting current sheet can potentially lead to multimessenger electromagnetic counterparts to a gravitational-wave event due to the acceleration of particles powering high-energy radiation, plasmoid mergers resulting in coherent radio signals, and pulsating emission due to the initial misalignment of the BH magnetosphere.  more » « less
Award ID(s):
2206609
PAR ID:
10539874
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
The Astrophysical Journal Letters
Date Published:
Journal Name:
The Astrophysical Journal Letters
Volume:
968
Issue:
1
ISSN:
2041-8205
Page Range / eLocation ID:
L10
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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