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iTHEMS Weekly News Letter


Cooperative agreement formed between Nara Women's Univ. and iTHEMS


iTHEMS has exchanged a cooperative agreement with Faculty of Science and Faculty of Human Life and Environment, Nara Women's Univ. (NWU), to promote gender diversity in Science. The picture shows the signing ceremony held on Nov.11 at NWU: Tetsuo Hatsuda from iTHEMS (left), Prof. T. Watanabe from Dean of Faculty of Science (middle) and Prof. M. Takada from Dean of Faculty of Human Life and Environment (right).

NWU is one of the two national women's universities in Japan and was founded 110 years ago on 1908. Currently, 21%(Math.), 10%(Bio.) and 13%(Phys. and Chem.) of women's Master students in Japanese national universities are produced from NWU.

As a first joint effort between iTHEMS and NWU, RIKEN researchers will deliver a series of lectures "Frontiers in mathematics, universe, matter, life and information" from the fall of 2020 for the 1st and 2nd year undergraduate students in NWU. The lecturers on 2020 are Tetsuo Hatsuda (iTHEMS, nuclear physics), Yuka Kotorii (AIP/iTHEMS, mathematics), Shigehiro Nagataki (CPR/iTHEMS, astrophysics), Makiko Nio (RNC, particle physics), Ryosuke Iritani (iTHEMS, biology), Ai Niitsu (CPR, chemistry), Shigenori Otsuka (R-CCS/iTHEMS, meteorology) and Emi Yukawa (CEMS, information).

Research News

Dr. Susumu Inoue thumbnail

Discovery of teraelectronvolt photons from gamma-ray bursts: A new window for exploring the most luminous explosions in the Universe


On January 14, 2019, TeV gamma rays (photons with energies a trillion times that of visible light) were clearly detected for the very first time from a gamma-ray burst (GRB; dubbed GRB 190114C) by the MAGIC telescopes. The very high energy of the individual photons as well as the high power of the total signal demonstrate that they must be produced by a physical process that is distinct from the previously known afterglow synchrotron radiation. Combined with extensive multiwavelength data obtained by a large number of observatories from the radio to GeV bands, the most likely mechanism is judged to be "inverse Compton” radiation associated with the afterglow, whereby some synchrotron photons are significantly boosted in energy by colliding with high-energy electrons [1]*. These findings were reported in two papers published on Nov. 21 in the journal Nature, one authored by the MAGIC Collaboration where Susumu Inoue of iTHEMS is the first corresponding author [2]*, and the other co-authored by a large team of astronomers including the MAGIC Collaboration [3]*.
* See the "References" below for [1],[2] and [3].

Caption for the figure:
Spectra of GRB 190114C in the X-ray to TeV gamma-ray energy range during two time intervals (top: 68-110 seconds after the beginning of the GRB; bottom: 110-180 seconds ibid.). Markers reflect data: white circles are observed MAGIC data; orange circles are MAGIC data corrected for intergalactic propagation effects. Curves are theoretical models: thin solid curves are synchrotron emission and inverse Compton emission shown separately; thick blue curves are their sum; dashed curves are inverse Compton emission when neglecting internal absorption effects.


  1. International press release from the MAGIC Collaboration
  2. "Teraelectronvolt emission from the g-ray burst GRB 190114C”
  3. "Observation of inverse Compton emission from a long g-ray burst"

Research News

Prof. Takashi Tsuboi thumbnail

Article about iTHEMS on Journal of the Mathematical Society of Japan


Professor Takashi Tsuboi, Deputy Program Director of iTHEMS posted an article about RIKEN iTHEMS on Journal of the Mathematical Society of Japan. See the article in the November issue from the following link.

Hot Topic

International WS "Collaborative Meeting on Supernova Remnants between Japan and USA" was held at RIKEN Wako campus and SUURI-COOL Kyoto


An international WS "Collaborative Meeting on Supernova Remnants between Japan and USA" was held at RIKEN Wako campus (Nov. 7-8, 2019) and SUURI-COOL Kyoto (Nov. 11-12, 2019) with Masaomi Ono (ABBL/iTHEMS), Shiu-Hang Lee (Kyoto Univ.) and Shigehiro Nagataki (ABBL/iTHEMS) as organizers. The aim of this workshop was to bring together experts including young researchers on supernova remnants and other related topics, such as supernovae, progenitor stars, and neutron stars, for active discussion and to initiate possible collaborations among the participants. In both 1st and 2nd weeks, there were about forty participants. Experts from USA mainly on supernova remnants gave excellent talks from both aspects of theories and observations. Not only supernova remnants but also many other related topics were presented by participants from Japan and Taiwan including students. During the workshop, many possible future collaborations were intensively discussed.

Seminar Report

Math Seminar talks by Dr. Atsushi Ito


The iTHEMS Math seminar was held on 8 Nov., inviting Atsushi Ito from Nagoya university. The title of the talk was "Some topics in projective geometry of algebraic varieties". The main subject of the talk was the Gauss map and the dual variety of an algebraic variety, which reflect the behavior of the tangent spaces at a moving point of the variety. In the first part, the speaker explained the duality theorem of the dual variety and the original variety, which holds in the usual setting but fails in the unusual (that is, in positive characteristic) setting. In the second part, we considered the dimension of the dual varieties. The main result says that the gap of the dimension of the dual variety from the expected dimension is determined by a fibration structure of the variety with a good fibres.

Upcoming Events


Young Researcher Association for Biological Rhythms 2019 thumbnail

Young Researcher Association for Biological Rhythms 2019

December 7 - 8, 2019

Hiroshi Ito (Kyushu University)
Shigehiro Ohdo (Kyushu University)
Hiroyuki Kubota (Kyushu University)
Gen Kurosawa (RIKEN)
Shin G. Goto (Osaka City University)
Fustin Jean-Michel (Kyoto University)

Minako Isoda (Kyoto University)
Kyohei Uemoto (Kyoto University / Nara Institute of Science and Technology)
Shingo Gibo (RIKEN)
Motohide Seki (Kyushu University)
Yusuke Nakane (Nagoya University)
Arisa Hirano (University of Tsukuba)

This workshop is supported by RIKEN iTHEMS (RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program).

Venue: School of Agriculture, Ito Campus, Kyushu Univiesiry

Event Official Language: Japanese


Math Seminar

Multiple Zeta Values: Interrelation of Series and Integrals

December 17 at 16:00 - 18:10, 2019

Prof. Syuji Yamamoto (Associate Professor, Keio University)

Plan of the seminar: we separate each talk into two. In the first 60 minutes the speaker gives an introductory talk for non-mathematicians. After a short break, the second 60 minutes is spent for a bit more detailed talk for mathematicians (working in other areas). We welcome you joining both parts of the seminar or only the first/second half.

Venue: Seminar Room #160, 1F Main Research Building, RIKEN

Event Official Language: English


2019 RIKEN Symposium: Understand to Predict the properties of Things and Matters through Computational Calculations ~ Data Science, Natural Intelligence and Category Theory~

December 23 at 9:50 - 18:10, 2019

This workshop is supported by RIKEN iTHEMS (RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program).

Venue: Okochi Hall, 1F Laser Science Laboratory, RIKEN

Event Official Language: Japanese


RIKEN-Kyushu workshop on particle, nuclear and astrophysics thumbnail

RIKEN-Kyushu workshop on particle, nuclear and astrophysics

December 23 - 24, 2019

Emiko Hiyama (Kyushu U./RIKEN)
Hiroshi Suzuki (Kyushu U.)
Tetsuo Hatsuda (RIKEN)

Venue: Faculty of Science, Ito Campus, Kyushu University

Event Official Language: Japanese


iTHEMS Colloquium

Exploring the learning principle in the brain

January 16 at 15:30 - 17:00, 2020

Dr. Taro Toyoizumi (Team Leader, Center for Brain Science, RIKEN)

Venue: Large Meeting Room, 2F Welfare and Conference Building (Cafeteria), RIKEN

Broadcast: R311, Computational Science Research Building, R-CCS, Kobe Campus, RIKEN / SUURI-COOL (Kyoto), #204-205, 2F Maskawa Building for Education and Research, North Campus, Kyoto University / SUURI-COOL (Sendai), #303, 3F AIMR Main Building, Advanced Institute for Materials Research (AIMR), Tohoku University

Event Official Language: English

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