Waseda University
High Energy Astrophysics Group



Core-Collapse Supernovae and the Formation of Compact Objects

There is a wide diversity of stars in the universe. Stars with masses up to 100 times the mass of our sun are being formed in our present universe. Nuclear fusion occurs in the interior of stars, and generates heavy elements as time goes on. The final fate of the evolution of these stars depends on their mass. Massive stars with masses over 10 times the mass of our sun are especially interesting, forming iron cores near the end of their lives. Iron is the most stable element, so it does not fuse any more with other elements. When a certain amount of iron is formed, massive stars cannot withstand its heavy weight, and starts to collapse towards its center. This is called gravitational core-collapse, and is thought to be the fate of massive stars.

One of our main research topics is what happens after core-collapse. It is an important problem that has not yet been revealed theoretically. Observations show that these events may most likely lead to supernova, and the formation of neutron stars. But how the core-collapse causes supernova explosions remains a mystery. Neutrinos are expected to be playing a key role, but magnetic fields may be more essential. Our group is aiming to unravel these mysteries by constructing theoretical models, and conducting large scale simulations. We are also working on how we can confirm our theories from observation, such as neutrinos and future gravitational wave detection.

There is a particular class of neutron stars called magnetars, which have extremely strong magnetic fields. The magnetic fields of magnetars are a hundred-billion times stronger than a neodymium magnet. Magnetars are known for their outbursts called giant flares and the cause is thought to be their magnetic fields. Although quantum processes are important in such strong fields, they are not well understood yet. In our group, we study the quantum theory in strong electromagnetic fields to underderstand magnetars.

Stellar Structures and Evolution

Stellar structures are also a major topic that we are studying. The static structure of a star is fundamental in understanding its evolution and the later dynamical processes. Our group is working on how to formulate static structures of stars.

It is also known that over half of all stars form binary systems. In fact, massive stars are almost all in binary or multiple systems. Binary stars can interact during their evolution, which can lead to many interesting phenomena. Formation of neutron star binaries are especially important because they are the main targets of gravitational wave detection projects. Our group is investigating massive star binary evolution and their consequences.


Lab members are written in italic


Organizers: Wu Fan / Ryodai Kawaguchi / Taishi Sano

Contact: seminar_at_heap.phys.waseda.ac.jp (Please replace _at_ to @.)


NameEmail AddressLink
ProfessorShoichi Yamadashoichi@*1 rm
JSPS FellowMasamichi Zaizenzaizen@*2 rm
Assistant ProfessorWakana Iwakamiwakana@*2
Misa Ogataogata@*2
Ryuichiro Akahoakaho@*2 rm
Visiting ScientistMilad Delfan Azarimilad@*2
Motoyuki Saijosaijo@*2 rm
Yu Yamamotoyamamoto@*2
Laura Barriolaura@*2
PhD StudentWu Fanwu@*2
Akira Itoito@*2
Master's studentLiu Jiabaoliu@*2
Daiyuu Sakuraisakurai@*2
Narihiro Yamamotonariyama@*2
Rikutaro Yamazakiyamazaki@*2
Wu Tongyangwut@*2
UndergraduateTakahiro Kageyamakageyama@*2
Shion Kuriharakurihara@*2

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03-5286-1697 (Extension Number : 3667)


Room 07, 4F, N Tower, Bldg. No.55, 3-4-1 Ookubo, Shinjuku-ku, Tokyo, 169-8555, Japan
Yamada laboratory, Physics Department, Advanced Research Institute for Science and Engineering, Waseda University


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