Kavli IPMU Senior Fellow Eiichiro Komatsu Receives Nishina Memorial Prize

November 11, 2022
Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)

Max Planck Institute for Astrophysics Director and Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Senior Fellow Eiichiro Komatsu has been awarded the 2022 Nishina Memorial Prize, it was announced on November 10 by the Nishina Memorial Foundation.

The Nishina Memorial Prize commemorates the achievements of the late Dr. Yoshio Nishina and is an honor given to relatively young researchers who have made outstanding research achievements in atomic and sub-atomic physics and their applications. It is the oldest and most prestigious physics award in Japan.

Six notable Japanese who have won the Nobel Prize in Physics, namely Reona Esaki, Masatoshi Koshiba, Makoto Kobayashi, Toshihide Masukawa, Shuji Nakamura, and Takaaki Kajita, have also received the award.

Komatsu is the fifth Kavli IPMU researcher to receive this award. The previous recipients are Kavli IPMU Director, California Institute of Technology Fred Kavli Professor of Theoretical Physics and Mathematics, and California Institute of Technology Walter Burke Institute for Theoretical Physics Director Hirosi Ooguri (2009); former Kavli IPMU Principal Investigator and Tohoku University Research Center for Neutrino Science Professor Kunio Inoue (2012); Kavli IPMU Visiting Senior Scientist and Kyoto University Professor Tsuyoshi Nakaya (2014); and Kavli IPMU Visiting Senior Scientist and Kyoto University Yukawa Institute for Theoretical Physics Professor Tadashi Takayanagi (2016).

This time, Komatsu received the Nishina Memorial Prize for his “contributions to the standard cosmology based on the cosmic microwave background.”

A period of rapid expansion in the very early universe, called “cosmic inflation,” provides an explanation for the observed homogeneity and isotropy of the Universe. However, to regard it as a key element of the standard cosmological model, it is necessary to find quantitative verification of the predictions of inflationary theory, such as the flatness of space and the generation of primordial curvature fluctuations that are adiabatic, almost scale-invariant, and follow a Gaussian distribution.

Komatsu, in collaboration with Princeton University Professor David Spergel, explored statistical properties of temperature fluctuations in the cosmic microwave background radiation with a three-point correlation function, and introduced a quantity known as the non-linear parameter (f_NL) to quantitatively evaluate the deviation from a Gaussian distribution. Komatsu applied this to observational data from the Cosmic Background Explorer (COBE) satellite to test its effectiveness, and then to data from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite. As a result, Komatsu and his collaborators were the first to find quantitatively that f_NL is consistent with zero and that primordial curvature fluctuations are consistent with a Gaussian distribution.

The WMAP science team analyzed in detail the power spectrum of temperature fluctuations in the cosmic microwave background radiation to determine the power spectrum of adiabatic primordial curvature fluctuations, verifying the predictions of inflationary theory. Komatsu played a central role in the analyses of WMAP data to detect a slight deviation from the scale invariance of primordial curvature fluctuations at a statistical significance of 5σ, which contributed to the selection of models of inflation. He also made a significant contribution to establishing the idea that the so-called “ΛCDM model,” with flat spatial geometry and a composition of matter and energy of 5% baryons, 25% cold dark matter, and 70% dark energy, can be regarded as the standard cosmological model.

“It has been an honor to work as a member of the WMAP team and I feel humbled to receive the Nishina Memorial Prize, which has such a long history. I am grateful to those who nominated me for the prize, to the selection committee for their recognition of our work, and to all those who have mentored me. For me, research in fundamental physics is about expanding the “horizon of physics,” which our predecessors have boldly challenged and pioneered over the years, with colleagues around the world. This prize encourages me to expand the horizon further,” said Komatsu.

A prize giving ceremony will be held in Tokyo on December 6.

Eiichiro Komatsu Education and Experience
2001 Doctor of Science, Tohoku University
2001 Postdoctoral Research Fellow (WMAP Fellow), Princeton University
2003 Assistant Professor of Astronomy, The University of Texas at Austin
2008 Associate Professor of Astronomy, The University of Texas at Austin
(2008 - 2010 Visiting Scientist, Institute for the Physics and Mathematics of the Universe)
2009 - 2012 Director, Texas Cosmology Center, The University of Texas at Austin
2010 - 2012 Professor of Astronomy, The University of Texas at Austin
(2010 - 2017 Visiting Senior Scientist, Kavli Institute for the Physics and Mathematics of the Universe)
2012 - currently Director, Max Planck Institute for Astrophysics
2017 - 2022 Principal Investigator, Kavli Institute for the Physics and Mathematics of the Universe
2022 Visiting Senior Scientist, Kavli Institute for the Physics and Mathematics of the Universe
2022 – current Senior Fellow, Kavli Institute for the Physics and Mathematics of the Universe