Magnetorotational collapse of massive stellar cores to neutron stars: Simulations in full general relativity

Journal Article · Wed Nov 15 04:00:00 EST 2006 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.74.104026· OSTI ID:20864134

Shibata, Masaru ^[1]; Liu, Y T; Stephens, Branson C ^[2]; Shapiro, Stuart L ^[2]

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1. Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro, Tokyo 153-8902 (Japan)
2. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080 (United States)

We study magnetohydrodynamic (MHD) effects arising in the collapse of magnetized, rotating, massive stellar cores to proto-neutron stars (PNSs). We perform axisymmetric numerical simulations in full general relativity with a hybrid equation of state. The formation and early evolution of a PNS are followed with a grid of 2500x2500 zones, which provides better resolution than in previous (Newtonian) studies. We confirm that significant differential rotation results even when the rotation of the progenitor is initially uniform. Consequently, the magnetic field is amplified both by magnetic winding and the magnetorotational instability (MRI). Even if the magnetic energy E{sub EM} is much smaller than the rotational kinetic energy T{sub rot} at the time of PNS formation, the ratio E{sub EM}/T{sub rot} increases to 0.1-0.2 by the magnetic winding. Following PNS formation, MHD outflows lead to losses of rest mass, energy, and angular momentum from the system. The earliest outflow is produced primarily by the increasing magnetic stress caused by magnetic winding. The MRI amplifies the poloidal field and increases the magnetic stress, causing further angular momentum transport and helping to drive the outflow. After the magnetic field saturates, a nearly stationary, collimated magnetic field forms near the rotation axis and a Blandford-Payne-type outflow develops along the field lines. These outflows remove angular momentum from the PNS at a rate given by J{approx}{eta}E{sub EM}C{sub B}, where {eta} is a constant of order {approx}0.1 and C{sub B} is a typical ratio of poloidal to toroidal field strength. As a result, the rotation period quickly increases for a strongly magnetized PNS until the degree of differential rotation decreases. Our simulations suggest that rapidly rotating, magnetized PNSs may not give rise to rapidly rotating neutron stars.

• OSTI ID: 20864134
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 10 Vol. 74; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR MOMENTUM
AXIAL SYMMETRY
COMPUTERIZED SIMULATION
COSMOLOGY
ENERGY LOSSES
EQUATIONS OF STATE
GENERAL RELATIVITY THEORY
INSTABILITY
KINETIC ENERGY
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
NEUTRON STARS
REST MASS
ROTATION
STRESSES