Exploring the processes underlying supernova explosions and the formation of black holes.
Massive stars of mass larger than about 8 solar mass eventually collapse to a black hole or a neutron star. Associated with the gravitational collapse, supernova explosion, and in a special case, gamma-ray burst occur. In these high-energy phenomena that occur in strong gravitational field, all four interaction forces in nature (gravitational, electromagnetic, strong, and weak interactions) play an important role. To theoretically understand these phenomena, numerical simulation incorporating various physical processes is required.
To perform a first-principle-based numerical simulation for gravitational collapse and supernova explosion, we have to solve Einstein’s equation, magnetohydrodynamics equations, and Boltzmann’s equation for neutrino radiation fields. This implies that we have to solve highly nonlinear coupled equations as well as to evolve fields with 6 dimensional space composed of 3 real spaces and 3 phase spaces. In addition, we have to follow the evolution of chemical composition such as fractions of protons, neutrons, heliums, heavy nuclei, and electrons that obeys the laws of strong and weak interaction forces. 6-dimensional radiation hydrodynamic simulation in general relativity is the ultimate goal in this field. However, it is computationally quite expensive, and thus, it is not possible to do in the current computational resource even with a peta-flops machine such as “Kei”. Nevertheless, people in this field in the world believe that in the near future, it will be possible to do such a grand-challenge simulation, and therefore, it is necessary to prepare numerical codes for such simulation. As a mile-stone work toward the ultimate goal, we will solve the following problems in the next five years using the “Kei” computer. All these issues are currently the so-called grand-challenge topics in the world:
1: Solving the radiation hydrodynamic equations for 3 real spaces and 1 energy space with high accuracy, we will clarify the mechanism of supernova explosion in the so-called neutrino-heating scenario. Enhancement of neutrino heating by hydrodynamic instabilities in 3 spatial dimensions will be clarified for the first time.
2: Solving the magneto-hydrodynamic equations in 3 spatial dimensions with high accuracy, incorporating micro physical processes, we will clarify the magneto-turbulent mechanism of supernova explosion. Process for the generation of strong magnetic fields and associated jets will be clarified.
3: Solving the radiation hydrodynamic equations for 3 real spaces and 1 energy space in general relativity for the first time, we will attack to solve the mechanism of supernova explosion in the neutrino-heating scenario and to clarify the formation process of black hole in nature.
4: Solving the radiation hydrodynamic equations for 3 real and 3 phase spaces (in total 6 dimensions), we will try to clarify the mechanism of supernova explosion in the neutrino-heating scenario. 6 dimensional radiation hydrodynamic simulations will be performed for the first time.
Masaru Shibata: Professor, Yukawa Institute for Theoretical Physics, Kyoto University
Yudai Suwa: Associate Professor, Yukawa Institute for Theoretical Physics, Kyoto University
Kenta Kiuchi: Assistant Professor, Yukawa Institute for Theoretical Physics, Kyoto University
Yuuichirou Sekiguchi: Assistant Professor, Yukawa Institute for Theoretical Physics, Kyoto University
Hiroki Nagakura: Research Fellow, Yukawa Institute for Theoretical Physics, Kyoto University
Shoichi Yamada: Professor, Faculty of Science and Engineering, Waseda University
Wakana Iwakami: Research Fellow, Faculty of Science and Engineering, Waseda University
Kousuke Sumiyoshi: Professor, Department of Liberal Arts, Numazu National College of Technology
Kei Kotake: Associate Professor, Faculty of Science, Fukuoka University
Tomoya Takiwaki: Assistant Professor, Center for Computational Astrophysics, National Astronomical Observatory of Japan