Collapse of magnetized hypermassive neutron stars in general relativity: Disk evolution and outflows

Journal Article · Fri Feb 15 04:00:00 EST 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.77.044001· OSTI ID:21039121

Stephens, Branson C; Shapiro, Stuart L; Liu, Yuk Tung ^[1]

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1. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

We study the evolution in axisymmetry of accretion disks formed self-consistently through collapse of magnetized hypermassive neutron stars to black holes. Such stars can arise following the merger of binary neutron stars. They are differentially rotating, dynamically stable, and have rest masses exceeding the mass limit for uniform rotation. However, hypermassive neutron stars are secularly unstable to collapse due to MHD-driven angular momentum transport. The rotating black hole which forms in this process is surrounded by a hot, massive, magnetized torus and a magnetic field collimated along the spin axis. This system is a candidate for the central engine of a short-hard gamma-ray burst (GRB). Our code integrates the coupled Einstein-Maxwell-MHD equations and is used to follow the collapse of magnetized hypermassive neutron star models in full general relativity until the spacetime settles down to a quasistationary state. We then employ the Cowling approximation, in which the spacetime is frozen, to track the subsequent evolution of the disk. This approximation allows us to greatly extend the disk evolutions and study the resulting outflows, which may be relevant to the generation of a GRB. We find that outflows are suppressed when a stiff equation of state is assumed for low-density disk material and are sensitive to the initial magnetic field configuration.

• OSTI ID: 21039121
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 4 Vol. 77; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCRETION DISKS
APPROXIMATIONS
BLACK HOLES
COSMIC GAMMA BURSTS
COSMOLOGY
EQUATIONS OF STATE
GENERAL RELATIVITY THEORY
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MASS
NEUTRON STARS
ROTATION
SPACE-TIME
SPIN