14–18 Feb 2011
Wenner Gren Center
Europe/Stockholm timezone

Effects of magnetic dissipation in a collapse of massive star

15 Feb 2011, 14:40
20m
Wenner-Gren Center, floor 7, Hörsalen (Wenner Gren Center)

Wenner-Gren Center, floor 7, Hörsalen

Wenner Gren Center

Sveavägen 164 SE-113 46 Stockholm Sweden

Speaker

Dr Hidetomo Sawai

Description

Magnetically driven supernovae have been studied well for several years. Although core-collapse simulations without magnetic fields to date cannot reproduce a successful explosion, every numerical simulation with initially strong magnetic field and rotation shows a jet-like explosion along the rotation axis. There a key agent of explosion is toroidal-magnetic pressure amplified by differential rotation around a proto-neutron star surface. Meanwhile, Thompson et al. (2005) showed by their 1-D hydrodynamic simulations that a turbulent resistivity originating from magnetorotational instability (MRI) dissipates magnetic fields, and generated thermal pressure helps the explosion. However, in their study, dynamical roles of magnetic pressure are not treated, since their computation is hydrodynamic and in 1-D. Here, we have done 2-D magnetohydrodynamic simulations of a collapse of massive star with inclusion of a magnetic dissipation. We found that a magnetic dissipation is negative reinforcer for an energetic explosion. Due to magnetic dissipation, the amplification rate of toroidal magnetic fields decreases, which in turn lower the power of the engine. The low-power engine in principle could produce finally same explosion energy as a high-power one, provided sizes of energy reservoirs are same. However, the deeper the collapse proceeds, the harder the matter to be ejected, and thus the low-power engine results in a weak explosion

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