Magnetorotational Effects on Anisotropic Neutrino Emission and Convection in Core‐Collapse Supernovae

Kotake, Kei; Sawai, Hidetomo; Yamada, Shoichi; Sato, Katsuhiko

doi:10.1086/392530

Cited by 138 publications

(142 citation statements)

References 47 publications

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“…as in previous studies of collapsars ( Mizuno et al 2004a( Mizuno et al , 2004b and SNe ( Kotake et al 2004). Here 0 and R 0 are parameters of our model.…”

Section: Initial Conditionssupporting

confidence: 57%

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Nucleosynthesis in Magnetically Driven Jets from Collapsars

Fujimoto

Nishimura

Hashimoto

2008

ApJ

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We have made detailed calculations of the composition of magnetically driven jets ejected from collapsars, or rapidly rotating massive stars, based on long-term magnetohydrodynamic simulations of their core collapse with various distributions of magnetic field and angular momentum before collapse. We follow the evolution of the abundances of about 4000 nuclides from the collapse phase to the ejection phase and through the jet generation phase using a large nuclear reaction network. We find that the r-process successfully operates only in energetic jets (>10 51 ergs), such that U and Th are synthesized abundantly, even when the collapsar has a relatively weak magnetic field (10 10 G) and a moderately rotating core before the collapse. The abundance patterns inside the jets are similar to those of the r-elements in the solar system. About 0.01-0.06 M of neutron-rich, heavy nuclei are ejected from a collapsar with energetic jets. The higher energy jets have larger amounts of 56 Ni, varying from 3.7 ; 10 À4 to 0.06 M . Less energetic jets, which eject small amounts of 56 Ni, could induce a gamma-ray burst (GRB) without a supernova, such as GRB 060505 or GRB 060614. Considerable amounts of r-elements are likely to be ejected from GRBs with hypernovae, if both the GRB and hypernova are induced by jets that are driven near the black hole.

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“…as in previous studies of collapsars ( Mizuno et al 2004a( Mizuno et al , 2004b and SNe ( Kotake et al 2004). Here 0 and R 0 are parameters of our model.…”

Section: Initial Conditionssupporting

confidence: 57%

“…We have extended the code to include a realistic equation of state (EOS) (Kotake et al 2004) based on relativistic mean field theory (Shen et al 1998). For the lower density regime ( < 10 5 g cm À3 ), where no data are available in the Shen EOS table, we use another EOS (Blinnikov et al 1996).…”

Section: Input Physics and Numerical Codementioning

confidence: 99%

Nucleosynthesis in Magnetically Driven Jets from Collapsars

Fujimoto

Nishimura

Hashimoto

2008

ApJ

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“…This is rather slow compared to the conditions considered in many of the core-collapse simulations performed by other groups (e.g., Ott et al 2004;Kotake et al 2004). The reasons for our choice of the initial rotation law were explained in detail at the beginning of Sect.…”

Section: A Simulation With Rotationmentioning

confidence: 91%

Two-dimensional hydrodynamic core-collapse supernova simulations with spectral neutrino transport

Buras

Janka²,

Rampp³

et al. 2006

A&A

292

463

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Spherically symmetric (1D) and two-dimensional (2D) supernova simulations for progenitor stars between 11 M and 25 M are presented, making use of the Prometheus/Vertex neutrino-hydrodynamics code, which employs a full spectral treatment of neutrino transport and neutrino-matter interactions with a variable Eddington factor closure of the O(v/c) moments equations of neutrino number, energy, and momentum. Multi-dimensional transport aspects are treated by the "ray-by-ray plus" approximation described in Paper I. We discuss in detail the variation of the supernova evolution with the progenitor models, including one calculation for a 15 M progenitor whose iron core is assumed to rotate rigidly with an angular frequency of 0.5 rad s −1 before collapse. We also test the sensitivity of our 2D calculations to the angular grid resolution, the lateral wedge size of the computational domain, and to the perturbations which seed convective instabilities in the post-bounce core. In particular, we do not find any important differences depending on whether random perturbations are included already during core collapse or whether such perturbations are imposed on a 1D collapse model shortly after core bounce. Convection below the neutrinosphere sets in 30−40 ms after bounce at a density well above 10 12 g cm −3 in all 2D models, and encompasses a layer of growing mass as time goes on. It leads to a more extended proto-neutron star structure with reduced mean energies of the radiated neutrinos, but accelerated lepton number and energy loss and significantly higher muon and tau neutrino luminosities at times later than about 100 ms after bounce. While convection inside the nascent neutron star turns out to be insensitive to our variations of the angular cell and grid size, the convective activity in the neutrino-heated postshock layer gains more strength in better resolved models. We find that low (l = 1, 2) convective modes, which require the use of a full 180 degree grid and are excluded in simulations with smaller angular wedges, can qualitatively change the evolution of a model. In case of an 11.2 M star, the lowest-mass progenitor we investigate, a probably rather weak explosion by the convectively supported neutrino-heating mechanism develops after about 150 ms post-bounce evolution in a 2D simulation with 180 degrees, whereas the same model with 90 degree wedge fails to explode like all other models. This sensitivity demonstrates the proximity of our 2D calculations to the borderline between success and failure, and stresses the need to strive for simulations in 3D, ultimately without the constraints connected with the axis singularity of a polar coordinate grid.

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“…It is still unclear which processes may convert some of the released gravitational binding energy of order O(10 53 ) erg into the typically observed kinetic and internal energy of the ejecta of O(10 51 ) erg = 1 Bethe [B] needed to blow off the stellar envelope. While most state-of-the art simulations investigate a mechanism based on neutrino heating in combination with hydrodynamical instabilities, such as , others explore the alternative magneto-rotational mechanism (Leblanc & Wilson 1970;Kotake et al 2004a;Burrows et al 2007a;Mikami et al 2008;Takiwaki et al 2009), or the acoustic mechanism which is driven by strong core g-modes (Burrows et al , 2007b. For a recent review see Janka et al (2007).…”

Section: Introductionmentioning

confidence: 99%

The influence of model parameters on the prediction of gravitational wave signals from stellar core collapse

Scheidegger

Käppeli

Whitehouse

et al. 2010

A&A

106

166

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We present a gravitational wave (GW) analysis of an extensive series of three-dimensional magnetohydrodynamical core-collapse simulations. Our 25 models are based on a 15 M progenitor stemming from (i) stellar evolution calculations; (ii) a spherically symmetric effective general relativistic potential, either the Lattimer-Swesty (with three possible compressibilities) or the Shen equation of state for hot, dense matter; and (iii) a neutrino parametrisation scheme that is accurate until about 5 ms postbounce. For three representative models, we also included long-term neutrino physics by means of a leakage scheme, which is based on partial implementation of the isotropic diffusion source approximation (IDSA). We systematically investigated the effects of the equation of state, the initial rotation rate, and both the toroidal and the poloidal magnetic fields on the GW signature. We stress the importance of including of postbounce neutrino physics, since it quantitatively alters the GW signature. Slowly rotating models, or those that do not rotate at all, show GW emission caused by prompt and proto-neutron star (PNS) convection. Moreover, the signal stemming from prompt convection allows for the distinction between the two different nuclear equations of state indirectly by different properties of the fluid instabilities. For simulations with moderate or even fast rotation rates, we only find the axisymmetric type I wave signature at core bounce. In line with recent results, we could confirm that the maximum GW amplitude scales roughly linearly with the ratio of rotational to gravitational energy at core bounce below a threshold value of about 10%. We point out that models set up with an initial central angular velocity of 2π rad s −1 or faster show nonaxisymmetric narrow-band GW radiation during the postbounce phase. This emission process is caused by a low T/|W| dynamical instability. Apart from these two points, we show that it is generally very difficult to discern the effects of the individual features of the input physics in a GW signal from a rotating core-collapse supernova that can be attributed unambiguously to a specific model. Weak magnetic fields do not notably influence the dynamical evolution of the core and thus the GW emission. However, for strong initial poloidal magnetic fields ( 10 12 G), the combined action of flux-freezing and field winding leads to conditions where the ratio of magnetic field pressure to matter pressure reaches about unity which leads to the onset of a jet-like supernova explosion. The collimated bipolar out-stream of matter is then reflected in the emission of a type IV GW signal. In contradiction to axisymmetric simulations, we find evidence that nonaxisymmetric fluid modes can counteract or even suppress jet formation for models with strong initial toroidal magnetic fields. The results of models with continued neutrino emission show that including of the deleptonisation during the postbounce phase is an indispensable issue for the quantitative prediction of GWs fro...

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Magnetorotational Effects on Anisotropic Neutrino Emission and Convection in Core‐Collapse Supernovae

Cited by 138 publications

References 47 publications

Nucleosynthesis in Magnetically Driven Jets from Collapsars

Nucleosynthesis in Magnetically Driven Jets from Collapsars

Two-dimensional hydrodynamic core-collapse supernova simulations with spectral neutrino transport

The influence of model parameters on the prediction of gravitational wave signals from stellar core collapse

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