Visit to School of Science-Affiliated Facilities

Vol.1 RESCEU (Research Center for the Early Universe)

  • Written by Kazuo Makishima (Director of RESCEU, Professor of Physics) in May 2007

Translated into English in May 2010

RESCEU, its predecessor and the present form

RESCEU is one of the four facilities affiliated to the School of Science that are located on Hongo Campus. The research subject of the Center is an integrated field of physics and astronomy: the origin and evolution of the Universe, based on the Big Bang scenario that announced the beginning of the Universe. The Center, the most recent of the facilities to be affiliated to the School of Science that were established before the incorporation of the University, has witnessed and recorded the radical changes in the environment of basic research from the bursting of the bubble economy to the present day.

When the Ministry of Education, presently MEXT (Ministry of Education, Culture, Sports, Science and Technology), established the grant for “Basic Research for COE (Centers of Excellence) Formation” as a large-scale grants-in-aid for scientific research in 1995, ten faculty members from the Departments of Physics and Astronomy cooperated closely and applied for the grant with a proposal called “Exploration of the Early Universe” that focused on the relation between the Early Universe and elementary particles. Prof. Katsuhiko Sato, who is a professor emeritus of the University from this year (fiscal 2010), was the group leader and Prof. Tsuneyoshi Kamae, professor emeritus of the University, was the advisor. Their proposal was adopted by the Ministry as one of the six themes for the first term. Since there was no overhead expense system at that time, universities were obligated to support related building maintenance with the grants they received. Using part of the grant, we set up an administration office and a computer room at the piloti of the Faculty of Science Bldg.4 and a clean room on the 6th floor of the same building. This is how RESCEU, in its predecessor form, was established as one of the affiliated facilities of the School of Science.

At first, the COE research was funded for the period of 1995 - 1999. However, two more years of funded research were allowed because the research had developed to an advanced level and it was highly rated by an international evaluation committee in 1998. The following is an extracted and modified version of the final evaluation given by the Ministry of Education.

To humankind's fundamental question on “How the Universe was created, evolved and developed its present shape with great diversity,” the following scenario was accepted around 1990, based on the general relativity and the elementary particles theory. This stipulates that a micro universe was created in quantum fluctuations, which appeared as a macro Big Bang universe, in which galaxies and other celestial structures formed. The members of the COE group, named themselves the “Research Center for the Early Universe (RESCEU),” and worked on their research with a world-class lineup to flesh out this abstract scenario.

They conducted theoretical studies, numerical experiments, and ground-based optical and space X-ray observations. At the same time they conducted repeated balloon experiments for antiproton detections as well as an effort to map out the Universe through international cooperation. They also drew on the MAGNUM telescope in Hawaii as well as the first submillimeter-wave telescope in Japan, situated at the top of Mt. Fuji, and they carried out a direct search for dark matter particles via the Kamioka Observatory, which is located underground in the Kamioka mine. Our understanding of the birth of the stars and of the supernova explosion, which is the last stage of a star, was enhanced, and black holes were found throughout the Universe. The asymmetry between matter and antimatter became clear, and the nature of dark matter was narrowed down. Even the existence of dark energy became more likely. All these achievements succeeded in dramatically reinforcing the scenario of the birth and evolution of the Universe, which was developed based on the concepts of inflation and the Big Bang.

As described above, the COE research has achieved many better-than-expected results on the question of the Early Universe and the cosmic evolution, which is one of the main themes of physics, on the basis of new ideas and steady plans. Their research is also considered to be highly significant from the perspective of the formation of a worldwide Center of Excellence.

“Basic Research for COE Formation,” a combination of competitive funds and operational expenses, was an excellent system that allowed large-scale research at a graduate school level to be implemented in a purely bottom-up manner. However, the bursting of the bubble economy affected the fields of basic science, leading to a trend for budget reduction, severe competition for grants, and distinction of rank in similar fields. As a result, this “well-planned” program was terminated at the end of fiscal year 2001. After that, in the biting storm of incorporation that swept national universities, large-scale competitive funds were transformed from “21st Century COE” and “Attractive Graduate School Initiative” into “Global COE” and “World Premier International Research Center Initiative”.

Establishment of RESCUE in its present form

After the research period of the “Basic Research for COE Formation” was over, we were encouraged to set up the established research organization as an internal facility under the ministerial ordinance. The Departments of Physics and Astronomy agreed to provide two and one faculty positions respectively, with which Prof. Sato and I (Makishima) were able to make a budget request (Fig. 1). Thanks to the tremendous assistance of the related administrative staff, RESCUE was reborn as one of the School of Science Affiliated Facilities under the ministerial ordinance in 1999.

Figure 1

Figure 1: Part of the cartoon used for a budget request submitted to the Ministry of Education during the establishment of the Center

Even with an additional post provided by the Ministry of Education, RESCUE is a small organization consisting of four faculty members, as well as a director (under a joint appointment), fixed-term part-time administrative staff, one or two fixed-term researchers, several JSPS postdoctoral fellows, and about 10 graduate students. It used to be located in the prefab building behind the Second Refectory but has been on the 6th floor of the Faculty of Science Bldg.4 since 2005. There are only two divisions: one is the “Division for the Early Universe,” which understands the Universe through a top-down approach based on pure theoretic study; the other is the “Division for the Early Universe Data Analysis,” which establishes a picture of the Universe through a bottom-up approach based on observational results. To bridge the gap between them, RESCUE has two unique mechanisms.

One of these mechanisms is the establishment of a division for “Cosmology based on Elementary Particles Theory,” for which a visiting professor position is offered. Every year, two to three international researchers visit Japan by rotation and contribute to the activities of the Center. Thanks to the cooperation of Prof. Okamura, Executive Vice President of the University, the necessary length of stay for a visiting professor was shortened from 3 months to 1 month from this fiscal year (FY 2007). Considering the fact that outstanding scientists cannot afford to stay away from their own facilities for a long period of time, this revised requirement meant broadened freedom for prospective visiting scientists.

The other mechanism is for the Center to work in partnership with about 10 “research collaborators” who are selected mainly from the Department of Physics, the Department of Astronomy, and the Institute of Astronomy (one of the School of Science-Affiliated Facilities). They benefit from the structure of the Center, and enhance its outcome. The Center itself focuses on theoretical studies, but about half of the research collaborators are engaged in observational and experimental studies. The Center is actually producing active research results with its observational equipment, built under the COE grant, and run with the Center's operational expenses. Thanks to this system, the Center has become a diversified management organization with seven projects, and the Center's flags can be found on the top of Mt. Fuji, in the Kamioka mine, as well as in Hawaii, North America, the Andes, the Antarctic Pole, and even in space outside the earth's atmosphere.

The Center has been actively organizing international symposia since its COE period. Thanks to the diversity of the Center and Prof. Sato's scientific attraction, the symposia have been a great success. Dr. Stephen William Hawking has been invited several times (Fig.2), and when he visited the University of Tokyo to deliver a lecture in November 2001, the line of audience stretched from in front of the venue (Yasuda Auditorium) almost to the Akamon (Red Gate), a distance of about 480 meters.

Figure 2

Figure 2: The 5th RESCEU symposium held on Tokyo University's Hongo Campus from November 13 - 16, 2001: The topic was New Trends in Theoretical and Observational Cosmology, for which Dr. Hawking (in the wheelchair, front line center) was invited to speak.

Activities and Achievements

Figure 3

Figure 3: BESS experiment apparatus about to be carried aloft by a balloon on December 13, 2004 near the McMurdo Station, an American Antarctic research station

As one example of the Center's 7 projects, let me introduce BESS (Balloon-Borne Experiments with Super conducting Spectrometer). The late professor Shuji Orito, a key member of RESCUE, started BESS. Although Prof. Orito passed away in the middle of the project, on 14 November, 2000, it was taken over by Tomoyuki Sanuki, who was an assistant professor at the Department of Physics at that time, and Prof. Akira Yamamoto of KEK (High Energy Accelerator Research Organization). The BESS collaboration consists of groups from the University of Tokyo, KEK, Kobe University, and JAXA (Japan Aerospace Exploration Agency), as well as several American research groups.

There is a theory that a large number of mini-black-holes that could have been formed during the Early Universe “evaporate” while generating particles and antiparticles. This theory will be verified if we can detect antiprotons coming from outer space. Drawing upon state-of-the-art ultrathin superconducting magnets and elementary particle detector technologies, the BESS collaborators developed a balloon-borne experiment for accurately identifying charged particles. Since 1993, they have succeeded in detecting an extremely large number of antiprotons through repeated balloon flights conducted in northern Canada near the geomagnetic pole. Although most of them are secondary antiprotons produced in interstellar space, there is a possibility that antiprotons created through black hole evaporations could be hiding among them. BESS has also detected cosmic-ray muons and cosmic-ray protons with unprecedented accuracy, which has tremendously changed the history of cosmic-ray measurements. In December 2004, the BESS collaborators succeeded in detecting more than a thousand antiprotons through a balloon flight around the South Pole (Fig.3), during which 9 hundred million cosmic-ray events were detected.

Future of the Center

During the 12 years from the Center's establishment to date, study on the Universe has developed dramatically. Thanks to the Hubble Space Telescope and the WMAP (Wilkinson Microwave Anisotropy Probe) satellite, a number of concepts have been confirmed. For example, the Hubble constant that represents the rate of expansion of the universe has been accurately measured as H0=72km/s/Mpc. The universe has an Euclidean geometry, and it is 13.7 billion years old. Dark energy accounts for about 3/4 of the energy density and most of the remaining 1/4 is dark matter. The Center did not participate in these projects directly, but both Prof. Yoshii's group (through deep surveys of galaxies) and Prof. Suto's group (through statistics of clusters of galaxies) had predicted the dominance of dark energy. And the MAGNUM telescope led us to consistent values with the above results.

More importantly, these latest observational data have resulted in confirming the notion of inflation, which Prof. Sato proposed in the 1980's. The Center is just about to reach the answer to the question that has long puzzled humankind: “How was the universe created?” Because of these achievements, the Center received high ratings again when it had an external evaluation together with the Department of Physics in January 2005.

In this way, we began to understand the mechanism which created the Universe. However, we have come across another huge mystery, which is: What is the nature of dark energy that accelerates the cosmic expansion and affects its destiny? This is an extremely important theme that 21st century physics must challenge. At the end of fiscal 2008, the Center faced the end of 10 years of financial support that had been a rule before the University's incorporation. Under the new system, as an independent corporate entity, the University's procedure for continuation of a time-limited internal organization has changed. Still, we wish to continue expansively our self-improvement toward the next decade, putting dark energy at the center of our research. This year, we took a step forward in this direction; with Prof. Suto as a coordinator, our proposal, “International Research Network for Dark Energy Study,” was adopted by JSPS Core-to-Core Program (Integrated Action Initiative).

Project 1: Very Early Universe and Long-Scale Structure
This is to theoretically derive a picture of the birth and evolution of the Universe, with cosmology and the fundamental laws of the elementary particles theory as a starting point.
Project 2: Theory of Galaxy Evolution
This is to establish a theoretical picture of the evolution of celestial objects based on astronomical observational data on supernova and nucleosynthesis.
Project 3: Optical to Near-infrared Observations of Active Galactic Nuclei
This is to explore the age of the Universe with a multiple-wavelength monitor of active galactic nuclei, using the MAGNUM telescope set up at the top of Haleakala Crater in Hawaii.
Project 4: Submillimeter-wave Observation
This is to investigate the birth of stars, using submillimeter-wave and terahertz wave technology at the top of Mt. Fuji and in the High Andes.
Project 5: Direct Search for Dark Matter and Solar Axions
This aims at a direct search for dark matter particles and solar axions, using a high-performance detector.
Project 6: Study of Galaxies and Structure of the Universe
This is to participate in the SDSS (Slone Digital Sky Survey) project which constructs detailed maps of the Universe and conducts wide-area sky surveys.
Project 7: Study of the Universe based on Balloon and Satellite Observations
7-1: This is to observe the Universe with X-rays using the “Suzaku” satellite launched in July 2005.
7-2: This is to conduct the BESS balloon experiment for detection of antimatter from high-geomagnetic-latitude places such as the South Pole.