Ishino Lab., Department of Physics, Faculty of Science, Okayama University
We are pleased to announce that Yusuke Takase of our laboratory will be awarded the degree of Doctor of Philosophy in Science on March 4, 2025. Congratulations! His doctoral thesis is now available on arXiv.
Title:
Design of the full-sky scanning strategy and systematic effect control in a cosmic microwave background probe
Link:
https://arxiv.org/abs/2503.03176
As a first step towards promoting exchange and joint research with Okayama University of Science, a reception was held on 7 March. It also served as a farewell party for Dr. Eiichiro Komatsu and his wife, as it was the last Friday that she would be spending in Okayama.
Thank you, Dr. Komatsu, for the fruitful discussions over the past month!
When you come to Okayama again. We will introduce you to some good restaurants with good drinks and food (and interesting physics stories…) when you come to Okayama again!
We look forward to seeing you again at both Okayama University and Okayama University of Science 😆.
On March 6, a mini-workshop on astrophysics was held with Dr. Komatsu, Director of Max Planck Institute for Astrophysics, Prof. Yamauchi and Nagao (Okayama University of Science), and members of our laboratory.
Okayama University of Science introduced their research on inflation theory, physics of the 21cm line (emitted from hydrogen atoms), and dark matter search, while Okayama University introduced our research on LiteBIRD, removal of foregrounds, and development of neutrino detectors.
Dr. Komatsu, who is staying at our lab, gave a special lecture on cosmic birefringence, and the discussion on the new physics of parity violation heated up. We hope that the synergy between Okayama University of Science, where theoretical astrophysics research is flourishing, and our lab, which promotes experimental physics, will enliven astrophysics in Okayama.
Prof. Shaul Hanany from the University of Minnesota visited our lab. on February 18-19.
Prof. Tomotake Matsumura and Dr. Guillaume Patanchon (Associate Professor at University of Paris-cite) from Kavli IPMU, University of Tokyo, and Dr. Keisuke Yoshihara, Project Manager of LiteBIRD from JAXA visited us at the same time. We had very heated discussions.
Prof. Hanany is the PI of PICO, the next generation CMB polarimetry satellite proposed to NASA, and we exchanged information and discussed scientific synergies in terms of the LiteBIRD project.
From our lab., Yusuke explained the differences in scanning strategies between LiteBIRD and PICO, as well as the advantages and disadvantages of each, and we had a very fruitful exchange of views.
At the social event, we were served with Okayama’s specialty, Spanish mackerel and yellow chives, which were very well received!
Dr. Eiichiro Komatsu, Director of the Max Planck Institute for Astrophysics, will stay at our laboratory for about three weeks under the RECTOR program “International Research Center for Astrophysical Data Analysis”.
Dr. Komatsu is a leading researcher in CMB research, and he has collaborated with our laboratory in the same project last year.
We hope to accelerate our CMB research including LiteBIRD through in-depth discussions for the next three weeks!
On February 12-13, the doctoral and master’s thesis review meetings were held, and Yusuke (D3), Kiyoshi (M2), and Ryuji (M2) from our laboratory gave presentations. I think all of them were able to show their abilities gained from their research during their doctoral and master’s periods.
Yusuke/Yuya/Kiyoshi participated in the international workshop CMB B-mode – NEXT held at KEK on January 27-29, and gave invited presentation respectively.
Following the LiteBIRD face-to-face meeting last week, many LiteBIRD collaborators as well as collaborators of the CMB ground-based experiment Simons Observatory (SO) and others gathered for a lively exchange of information beyond the boundaries of collaboration. The following is a list of the participants from our lab.
Kiyoshi Ikuma
Foreground Cleaning – Delta Maps
Yuya Nagano
HWP and systematics effects with asymmetric beams
Yusuke Takase
Systematic effects mitigation by spin moment decomposition
The LiteBIRD face-to-face (F2F) meeting was held at Kavli IPMU, the University of Tokyo, from January 20 to 24, and Hirokazu, Yusuke, Yuya, and KIyoshi participated. It was the first time in six months since the F2F meeting held in Vancouver in July of the last year, and discussions with the collaborators were enthusiastic.
The banquet held during the meeting included a performance by a Japanese taiko drum band, which was a great moment.
The recent (1/7) press release by Y. Takase et al. titled “How to Capture the Image of the Universe Immediately after its Birth through Satellite Observations” was published in the January 14, 2025 edition of the Nikkan Kogyo Shinbun (25 Science, Technology & University).
Link to the Article ：岡山大など、誕生時の宇宙の姿観測 測定誤差を最小化する新手法
The Nikkan Kogyo Shinbun, including back numbers, is available at the Okayama University Library.
Okayama University students and the general public are welcome to enter the library.
For details, please visit the library’s website.
A scientific paper by Mr. Takase, a third-year doctoral student in our laboratory, has been published in the Italian Journal of Cosmology and Astroparticle Physics (JCAP).
The paper proposes an optimal observation method for future satellite observations to validate inflationary models from polarimetric observations of the cosmic microwave background (CMB) radiation, and provides important guidelines for the design of future next-generation CMB polarimetric observation satellites. This research has been introduced in a press release by Okayama University and in Research Highlights.
Ishino Lab. is in charge of systematic error analysis and scan strategy design for LiteBIRD, a CMB polarimetric observation satellite led by the Japan Aerospace Exploration Agency (JAXA).
LiteBIRD is a scientific project that aims to verify inflation, which is believed to have occurred at the birth of the universe, by observing the polarization of the CMB in the entire cosmic sky with high precision. (For details, please see Research Activities)
In order to observe the entire sky of the universe, the satellite will rotate itself at the second Lagrangian point, 1.5 million km away from the earth, to scan the universe (Figure 1).
The key to highly accurate observation of the polarization of the CMB is to suppress systematic errors that originate in the observation equipment. In this study, we found the scan strategy parameters that minimize systematic errors by optimizing the angle and rotation speed of the satellite’s rotation axis.
For more information, please see the following press release/Reserch Highlights article.
Okayama University Press Release
誕生直後の宇宙の姿、衛星観測でどう捉えるか (Japanese)
Research Highlights
How to capture the universe after its birth through space observation (English)
Paper information
Title: Multi-dimensional optimisation of the scanning strategy for the LiteBIRD space mission
Authors：Y. Takase, L. Vacher, H. Ishino, G. Patanchon, L. Montier et al., LiteBIRD collaboration
DOI: 10.1088/1475-7516/2024/12/036
Link: https://iopscience.iop.org/article/10.1088/1475-7516/2024/12/036