Siegel 2014 超大质量中子星的转动驱动短暴的X射线余辉

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MHD数值模拟。

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Title:		Magnetically driven winds from differentially rotating neutron stars and X-ray afterglows of short gamma-ray bursts
Authors:		Siegel, Daniel M.; Ciolfi, Riccardo; Rezzolla, Luciano
Publication:		eprint arXiv:1401.4544
Publication Date:		01/2014
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics, General Relativity and Quantum Cosmology
Comment:		5 pages, 2 figures
Bibliographic Code:		2014arXiv1401.4544S

Abstract

Besides being among the most promising sources of gravitational waves, merging neutron-star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows lasting 10-10^4 s. These features are generally taken as evidence for a long-lived central engine powered by the magnetic spin-down of a uniformly rotating magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic and ideal magnetohydrodynamic simulations showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitively on the initial magnetic field geometry, while the stationary electromagnetic luminosity depends only on the magnetic energy initially stored in the system. We show that our model is compatible with the observed timescales and luminosities and express the latter in terms of a scaling relation that could be used to validate or confute the model.

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