Global Simulations of Magnetorotational Instability in the Collapsed Core of a Massive Star

Sawai, Hidetomo; Yamada, Shoichi; Suzuki, Hideyuki

doi:10.1088/2041-8205/770/2/l19

Cited by 58 publications

(55 citation statements)

References 21 publications

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“…We perform hydrodynamical simulations for MR-SNe with an MHD code, YAMAZAKURA 7 (Sawai et al 2013 , leading to millisecond rotation after the collapse. For the initial magnetic fields, we apply the same dipole-like configuration as Sawai & Yamada (2016) with a maximum value of2 10 G 11 around the center, while the value decreases to1 10 11 G at the edge of the core (∼1000 km).…”

Section: Mri-driven Core-collapse Supernovaementioning

confidence: 99%

“…The most promising process is the magneto-rotational instability (MRI), which converts rotation energy into magnetic energy. The MRI in proto-NS cores has been investigated on several scales (with related limitations) from local boxes (Obergaulinger et al 2009;Masada et al 2012;Rembiasz et al 2016) to global scales (Sawai et al 2013;Mösta et al 2015). Sawai & Yamada (2014, based on long-term global MHD simulations in axisymmetry, found a new explosion mechanism influenced by the MRI.…”

Section: Introductionmentioning

confidence: 99%

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The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability

Nishimura

Sawai

Takiwaki

et al. 2017

ApJL

177

197

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We investigated r-process nucleosynthesis in magneto-rotational supernovae, based on a new explosion mechanism induced by the magneto-rotational instability (MRI). A series of axisymmetric magnetohydrodynamical simulations with detailed microphysics including neutrino heating is performed, numerically resolving the MRI. Neutrino-heating dominated explosions, enhanced by magnetic fields, showed mildly neutronrich ejecta producing nuclei up toÃ 130 (i.e., the weak r-process), while explosion models with stronger magnetic fields reproduce a solar-like r-process pattern. More commonly seen abundance patterns in our models are in between the weak and regular r-process, producing lighter and intermediate-mass nuclei. These intermediate r-processes exhibit a variety of abundance distributions, compatible with several abundance patterns in r-processenhanced metal-poor stars. The amount of Eu ejectain magnetically driven jets agrees with predicted values in the chemical evolution of early galaxies. In contrast, neutrino-heating dominated explosions have a significant amount of Fe ( Ni 56 ) and Zn, comparable to regular supernovae and hypernovae, respectively. These results indicate magneto-rotational supernovae can produce a wide range of heavy nuclei from iron-group to r-process elements, depending on the explosion dynamics.

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Section: Mri-driven Core-collapse Supernovaementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability

Nishimura

Sawai

Takiwaki

et al. 2017

ApJL

177

197

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show abstract

“…Beyond this layer, the entropy gradient starts to rise again, but the angular velocity profile presents a significant degree of differential rotation, which sets the conditions for the development of the magnetorotational instability (MRI), that again can lead to a significant increase of the magnetic field strength (e.g. Balbus & Hawley 1998;Akiyama et al 2003;Masada et al 2007;Obergaulinger et al 2009;Sawai et al 2013;Mösta et al 2015;Rembiasz et al 2016Rembiasz et al , 2017Reboul-Salze et al 2019).…”

Section: Introductionmentioning

confidence: 99%

The impact of non-dipolar magnetic fields in core-collapse supernovae

Bugli

Guilet

Obergaulinger

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The magnetic field is believed to play an important role in at least some core-collapse supernovae if its magnitude reaches10 15 G, which is a typical value for a magnetar. In the presence of fast rotation, such a strong magnetic field can drive powerful jet-like explosions if it has the large-scale coherence of a dipole. The topology of the magnetic field is, however, probably much more complex with strong multipolar and small-scale components and the consequences for the explosion are so far unclear. We investigate the effects of the magnetic field topology on the dynamics of core-collapse supernovae and the properties of forming proto-neutron star (PNS) by comparing pre-collapse fields of different multipolar orders and radial profiles. Using axisymmetric special relativistic MHD simulations and a two-moment neutrino transport, we find that higher multipolar magnetic configurations lead to generally less energetic explosions, slower expanding shocks and less collimated outflows. Models with a low order multipolar configuration tend to produce more oblate PNS, surrounded in some cases by a rotationally supported toroidal structure of neutron-rich material. Moreover, magnetic fields which are distributed on smaller angular scales produce more massive and faster rotating central PNS, suggesting that higher order multipolar configurations tend to decrease the efficiency of the magnetorotational launching mechanism. Even if our dipolar models systematically display a far more efficient extraction of the rotational energy of the PNS, fields distributed on smaller angular scales are still capable of powering magnetorotational explosions and shape the evolution of the central compact object.

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“…While the former used a multi-group flux-limited diffusion treatment for the neutrino transport in a Newtonian framework, the latter approximated the effects of neutrino radiation by a parametrisation of the pre-bounce deleptonisation of the core. Albeit using simplified neutrino physics, the high-resolution global simulations of Sawai et al (2013) addressed one of the most severe problems in numerical models of magneto-rotational collapse, viz. the extremely high resolution required to resolve the fastest growing MRI modes.…”

Section: Introductionmentioning

confidence: 99%

Magnetic field amplification and magnetically supported explosions of collapsing, non-rotating stellar cores

Obergaulinger¹,

Janka²,

Aloy³

2014

Monthly Notices of the Royal Astronomical Society

102

117

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We study the amplification of magnetic fields in the collapse and the post-bounce evolution of the core of a non-rotating star of 15 M in axisymmetry. To this end, we solve the coupled equations of magnetohydrodynamics and neutrino transport in the two-moment approximation. The pre-collapse magnetic field is strongly amplified by compression in the infall. Initial fields of the order of 10 10 G translate into proto-neutron star fields similar to the ones observed in pulsars, while stronger initial fields yield magnetar-like final field strengths. After core bounce, the field is advected through the hydrodynamically unstable neutrino-heating layer, where non-radial flows due to convection and the standing accretion shock instability amplify the field further. Consequently, the resulting amplification factor of order five is the result of the number of small-eddy turnovers taking place within the time scale of advection through the post-shock layer. Due to this limit, most of our models do not reach equipartition between kinetic and magnetic energy and, consequently, evolve similarly to the non-magnetic case, exploding after about 800 ms when a single or few highentropy bubbles persist over several dynamical time scales. In the model with the strongest initial field we studied, 10 12 G, for which equipartition between flow and field is achieved, the magnetic tension favours a much earlier development of such long-lived high-entropy bubbles and enforces a fairly ordered large-scale flow pattern. Consequently, this model, after exhibiting very regular shock oscillations, explodes much earlier than non-magnetic ones.

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Global Simulations of Magnetorotational Instability in the Collapsed Core of a Massive Star

Cited by 58 publications

References 21 publications

The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability

The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability

The impact of non-dipolar magnetic fields in core-collapse supernovae

Magnetic field amplification and magnetically supported explosions of collapsing, non-rotating stellar cores

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