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December 22, 2017

Dreams of exploding stars

Picture of Shigehiro Nagataki

Shigehiro Nagataki, Chief Scientist

Astrophysical Big Bang LaboratoryChief Scientist Laboratories

Please describe your role at RIKEN.

As a principal investigator, I manage the Astrophysical Big Bang Lab. I also pursue my scientific goals as well as support lab members in realizing their research dreams.

Please briefly describe your current research. Why is it important?

My lab studies massive star explosions—astrophysical big bangs. Massive exploding stars synthesize heavy elements (that is, carbon and heavier elements). The Earth and our bodies are made of these heavy elements, including carbon, oxygen and iron. In other words, we were born from massive stars. We are studying how and why massive stars explode, as well as how and what kind of heavy elements these explosions produced.

What excites you the most about your current research?

Gamma-ray bursts are the most energetic explosions in the Universe and are sometimes the result of massive star explosions. We recently discovered evidence of why gamma-ray bursts occur by mathemati­cally simulating the propagation of relativistic jets emitted from progenitor stars, calculating the radiation transfer of the jets, and estimating the resulting brightness and spectrum of the gamma-rays.

Picture of  Nagataki  at work 

How and when did you join RIKEN?

I met Professor Emiko Hiyama at a meeting supported by the Ministry of Education, Culture, Sports, Science and Technology, and she invited me to give a talk at her laboratory at RIKEN. After that, I went for dinner with Professors Tetsuo Hatsuda and Hiyama, and I thought it would be really interesting to work with them. A few months later, I applied for RIKEN’s Associate Chief Scientist Program.

How has being at RIKEN helped your research?

Among other things, the Associate Chief Scientist Program guaranteed a 100-million-yen start-up budget, with which I could hire top-level researchers.

What are some technologies you use to conduct your research?

The K computer and Hokusai supercomputers are very important to crunch the data needed for our research.

What is the best thing about working at RIKEN?

I think that the barrier between laboratories is lower at RIKEN than at Japanese universities. For example, my lab has a close relationship with the Interdisciplinary Theoretical and Mathematical Sciences Program—I’m a deputy director and all my lab members are associates—which facilitates interdisciplinary communication and collaboration with other labs.

picture of Nagataki and the lab members 

What has been your most memorable experience at RIKEN?

I feel that the president is closer to us at RIKEN than at Japanese universities. When I was an associate chief scientist, I felt that the program was very good, but that some improvements were possible. So I proposed some improvements to President Hiroshi Matsumoto, together with all associate chief scientists, which were partially adopted. This interaction greatly enhanced the research environment I was working in.

Please tell us about your professional and personal goals.

I want to understand how the Universe was born by studying black holes, as they are also created as a result of massive star explosions or failures of massive stars to explode.

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