This section highlights our latest research activities, including publications, conference presentations, media coverage, and collaborative projects. We also share updates on team events and extracurricular activities that strengthen connections and promote a healthy work–life balance within the group.

• Feb. 9, 2026
  The undergraduate thesis presentation by Maria Arima, “Transonic Analysis of Outflows in Star-Forming Galaxies,” was selected for the Best Presentation Award. This is the third time our team has received this award, following 2022 and 2024. Congratulations!
• Feb. 4, 2026
  The undergraduate thesis presentations have been completed, and all three members of our team have successfully passed. Congratulations!
  Maria Arima, “Transonic Analysis of Outflows in Star-Forming Galaxies”: This thesis applies a transonic outflow model to star-forming galaxies in the early galaxy formation epoch and interprets recent high-redshift observations from a fundamental physical perspective.
  Taisei Nomura, “Dynamical Evolution of Self-Gravitating N-body Systems Using the Hermite Scheme”: This thesis implements the high accuracy Hermite time integration scheme in N-body simulations and examines its performance and potential applications.
  Kenta Hagiwara, “Fluid-Dynamical Simulation of the Flow Field around a Sprinter”: This thesis analyzes the aerodynamic drag around a 100-meter sprinter using fluid-dynamical simulations and obtains new insights into the surrounding flow field.
  
• Jan. 24, 2026
  Our coauthored paper with Kohei Hayashi (Sendai National College of Technology), Yuka Kaneda (Ph.D. student, 3rd year), and Michi Shinozaki (MSc student, 1st year), Cusp-to-Core Transition of Dark Matter Halos across Galaxy Mass Scales [arXiv:2507.22155], has been accepted for publication in Publications of the Astronomical Society of Japan (PASJ).
• Jan. 23, 2026
  The thesis defense of Kotaro Hiraki (Master’s student in Education, 2nd year) in the Education Degree Program, entitled “Intuitive Understanding of Physical Phenomena through Visualization of Numerical Simulations and Its Educational Applications,” was held, and he successfully passed. Congratulations!
• Jan. 22, 2026
  Our coauthored paper with Michi Shinozaki (MSc student, 1st year), Yuka Kaneda (Ph.D. student, 3rd year), and Kohei Hayashi (Sendai National College of Technology), entitled “The Characteristic Mass and Energy Conversion Efficiency in the Cusp-Core Transition of Dark Matter Haloes:Implications for Scaling Relations and Supernova Feedbacks,” which was submitted to Monthly Notices of the Royal Astronomical Society, has been posted on the preprint server arXiv. [arXiv:2601.13868]
• Jan. 21, 2026
  The individual defense of the master's thesis by Taisei Takeuchi (MSc student, 2nd year), entitled “Galaxy Interactions and Galaxy Evolution in the M81 Group,” has been successfully completed, and he will now move on to the public master's thesis presentation on Feb. 12.
• Jan. 20, 2026
  We visited the sports experimental wind tunnel facility at the Sports Fluid Engineering Laboratory building at the University of Tsukuba. Using the wind tunnel apparatus, it is possible to observe and analyze airflow generated by athlete motion. By combining simulations with experiments, we hope to deepen our understanding of sports movements and contribute to performance enhancement and injury prevention.
  

  

  

  
• Jan. 15, 2026
  These photos show the “Inquiry-Based Research Seminar,” a course open to first- through third-year undergraduate students. In this class, students propose and present their own hypotheses about how the dynamical evolution of star clusters orbiting a supermassive black hole differs from that of star clusters orbiting within a dark matter halo. After group discussions, they run numerical experiments using simulation codes they have written themselves to test their hypotheses. Whose hypothesis will turn out to be closest to the truth?
  

  

  

  
• Jan. 14 to Feb. 1, 2026
  Misa Yamaguchi (Ph.D. student, 1st year) is visiting the University of Vienna Observatory in Austria to conduct international collaborative research on galaxy evolution and the Galactic Habitable Zone.
• Jan. 1, 2026
  Happy New Year. Thank you for your continued interest and support. In 2026, together with my team members and collaborators, I aim to further expand our activities by launching new research projects, presenting our results at international conferences, and submitting papers.
• Dec. 17 to 19, 2025
  Our team members, including undergraduate thesis students, participate in “The 38th Symposium on Theoretical Astrophysics: Numerical Simulations and AI in Astrophysics,” held at the University of Tsukuba, and present their latest research results.
• Nov. 24 to Dec. 13, 2025
  Misa Yamaguchi (Ph.D. student, 1st year) is staying at Zhejiang University in Hangzhou, China, to conduct research on galaxy evolution.
• Nov. 29, 2025
  Our coauthored paper with Koki Ohtaki (University of Rome) and Yudai Kazuno (MSc 2022), Collision frequency between dark matter subhaloes within Milky Way-like galaxies, has been published online in New Astronomy. [New Astronomy / arXiv:2511.16464]
• Nov. 20, 2025
  Our coauthored paper with Koki Ohtaki (University of Rome) and Yudai Kazuno (MSc 2022), Collision frequency between dark matter subhaloes within Milky Way-like galaxies, has been accepted for publication in New Astronomy. [arXiv:2511.16464]
• Nov. 19, 2025
  At the international conference “The 3rd Shanghai Assembly on Cosmology and Structure Formation,” held at the Tsung-Dao Lee Institute, Shanghai Jiao Tong University, from Nov. 17 to 21, 2025, the latest results from my team were presented. Recent submissions entitled “Cusp-to-Core Transition of Dark Matter Halos across Galaxy Mass Scales” and “Simultaneous Formation of the Andromeda Giant Southern Stream and the Substructures in the Andromeda Halo” were introduced, leading to many questions and comments and resulting in very fruitful discussions.
  

  

  

  
• Nov. 12, 2025
  We submitted a co-authored paper titled "The Characteristic Mass and Energy Conversion Efficiency in the Cusp-Core Transition of Dark Matter Haloes: Implications for Scaling Relations and Supernova Feedbacks" , by Michi Shinozaki (MSc, 1st year), Masao Mori, Yuka Kaneda (PhD, 3rd year) and Kohei Hayashi (Sendai National College of Technology), submitted to Monthly Notices of the Royal Astronomical Society.
• Nov. 12, 2025
  Taisei Takeuchi (MSc, 2nd year) successfully completed the midterm review of his master’s thesis entitled “Galaxy Interactions and Evolution in the M81 Galaxy Group.”
• Nov. 6, 2025
  We submitted a coauthored paper with Yuka Kaneda (PhD, 3rd year & MSc. 2nd year), Yohei Miki(University of Tokyo), Takanori Kirihara (Kitami Institute of Technology), and Andreas Burkert (University Observatory Munich).
• Oct. 31 - Nov. 1, 2025
  At the “Workshop on the Formation of Astronomical Objects” held at the University of Tsukuba, nine members of our team presented their research: Yuka Kaneda(PhD, 3rd year), Misa Yamaguchi(PhD, 1st year), Taisei Takeuchi(MSc, 2nd-year), Kotaro Hiraki(MSc, 2nd year), Mayuka Oda(MSc, 1st year), Michi Shinozaki(MSc, 1st year), Maria Arima(under grads), Taisei Nomura(under grads), and Kenta Hagiwara(under grads).
• Oct. 30, 2025
  Two coauthored papers have been published in the Proceedings of the International Astronomical Union: with Ayami Hotta(2023 alumnus) and Koki Otaki(Research Fellow, University of Rome), Formation of the Andromeda Giant Stream and the 10 kpc Ring Structure in the Andromeda Galaxy; and with Yuka Kaneda(3rd-yr PhD. student) and Koki Otaki(Research Fellow, University of Rome), c-M relation of the sub-galactic dark matter halos and the effect of the cusp-to-core transition.
• Oct. 21, 2025
  I have been listed as a concurrent faculty member of the Sports Computational Science Division at the Center for Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba. See the ARIHHP website.
• Oct. 11, 2025
  Yuka Kaneda (3rd-yr Ph.D. student) has been selected for both the JSPS Postdoctoral Fellowship (PD) and the JSPS Overseas Research Fellowship for FY 2026. Congratulations!
• Oct. 6-10, 2025
  At the IAU Symposium “The Hidden Beauty of the Galactic Outskirts” held in Córdoba, Spain, Yuka Kaneda (D3) delivered a presentation titled “Detecting dark matter subhaloes and wandering intermediate-mass black holes through parallel stellar streams.”
• Oct. 6-7, 2025
  At the “17th Symposium on Discovery, Fusion, Creation of New Knowledge by Multidisciplinary Computational Sciences,” held at the Tsukuba International Congress Center, Mayuka Oda (M1) presented a poster on her research titled “Concentrations of Dark Matter Subhalos in Galaxy Clusters: Lognormal Distributions and a Revised Concentration-Mass Relation.”
• Oct. 2, 2025
  Kotaro Hiraki (2nd-yr M.S. student) delivered his Master’s thesis midterm presentation in the Graduate Program in Education (AY 2025) and successfully passed. Congratulations!
• Oct. 1, 2025
  Misa Yamaguchi (1st-yr Ph.D. student) has received a selection offer for the JSPS Research Fellowship (DC2) for FY 2026. Congratulations!
• Sep. 24, 2025
  I participated in the 2nd ARIHHP Salon and the 4th Cross-Departmental Academic Salon of the College of Systems and Information Engineering, “Toward deeper integration of health and sports science with computational science,” and presented a flash talk titled “Fluid dynamics linking athletes and black holes through computational science.”
• Sep. 16-18, 2025
  I held a collaboration meeting at the University of Tsukuba with Assistant Professor Sakurako Okamoto (Subaru Telescope, NAOJ) and Taisei Takeuchi (2nd-year M.S. student) on the evolution of the M81 galaxy group.
• Sep. 7-13, 2025
  I attended the international conference “COSMOLOGY 2025 @ ELBA ISLAND” in Italy and delivered a summary talk on our work on the structure and evolution of dark matter halos.
  

  

  

  

  The two photos on the left show the conference venue, Hotel Ermitage. The third photo features Paolo Salucci (SISSA: Scuola Internazionale Superiore di Studi Avanzati), and the fourth photo features Peter Berczik (National Academy of Sciences of Ukraine).

• Sep. 9, 2025
  Misa Yamaguchi (1st-year Ph.D. student) presented her latest results, “Formation history of substructures in the Andromeda halo probed by galaxy collision simulations,” at the Autumn Annual Meeting of the Astronomical Society of Japan (Yamaguchi).
• Sep. 4, 2025
  Misa Yamaguchi (1st-year Ph.D. student) gave a poster presentation at “Mirai no Hakase 2025,” held at Hitotsubashi Hall, Hitotsubashi University.
• Sep. 1-5, 2025
  I attended the international conference “The Dynamic Universe” at Kloster Seeon, Germany, and reported recent results on galaxy collisions and black hole activity.
  

  

  

  

  The two photos on the left show Kloster Seeon, the conference venue. Founded in 994 in Bavaria, Germany, the monastery sits on a small island in Lake Seeon. In the third photo, on the left is Prof. Andreas Burkert (LMU Munich) and in the center is Prof. Reinhard Genzel (Max Planck Institute for Extraterrestrial Physics). During my time as a research fellow at the Max Planck Institute for Astronomy (MPIA), Prof. Burkert was a generous mentor and we have remained close personally. Prof. Genzel received the 2020 Nobel Prize in Physics for observational research on the Galactic Center black hole. In the fourth photo, the person standing on the left is my longtime friend, Prof. Gerhard Hensler (Professor Emeritus, University of Vienna).

• Aug. 26, 2025
  We submitted a co-authored paper with Koki Otaki (University of Rome), Yohei Miki (University of Tokyo), and Daisuke Takahashi (University of Tsukuba), entitled “Accelerated Hermite Integrator for Orbital Integration with OpenACC and MPI”, to the Journal of Supercomputing.
• Aug. 18, 2025
  Misa Yamaguchi (1st yr Ph.D. student) presented her research (in Japanese) at the “Science Expo: Connecting Myself and the Future,” held as part of Expo 2025 Osaka, Kansai. Her talk focused on large-scale simulations of galaxy collisions, particularly a minor merger in the Andromeda Galaxy, through which she explained the complex composite structure of stellar streams and its role in understanding galaxy formation.
• Aug. 13, 2025
  Additional information on computational science has been included on the Research page.
• Aug. 1, 2025
  As of August 1, I have taken on an additional role as an affiliated faculty member in the Computational Sport Science Division at the Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba. In parallel with my primary research in astrophysics, I will apply my expertise in fluid dynamics and computational science to the field of sports science, aiming to understand the distinctive dynamics of various athletic disciplines from a physics-based perspective.
• Jul. 30, 2025
  We submitted a co-authored paper with Dr. Kohei Hayashi (Sendai National College of Technology), Yuka Kaneda (3rd-yr Ph.D. student), and Michi Shinozaki (1st-yr master's student), titled Cusp-to-Core Transition of Dark Matter Halos across Galaxy Mass Scales [arXiv:2507.22155] to PASJ.
• Jul. 26, 2025
  We submitted a co-authored paper with Dr. Koki Otaki (postdoctoral researcher at the University of Rome) and Yudai Kazuno (graduated in 2022), titled Collision frequency between dark matter subhaloes within Milky Way-like galaxies to the New Astronomy.
• Jul. 17, 2025
  We had a kickoff meeting with Assistant Professor Hashimoto, a member of the observational group at the University of Tsukuba, to launch a new collaborative study. The goal of the project is to validate theoretical predictions about the nature of dark matter through new observations and joint analysis.
• Jul. 11, 2025
  As part of the Undergraduate Research Experience Seminar, students visited the PEGASUS supercomputer, located in the annex of the Center for Computational Sciences at the University of Tsukuba. PEGASUS consists of 150 compute nodes equipped with GPU accelerators, each achieving a theoretical peak performance of 51 teraflops in double-precision floating-point operations. The system’s total theoretical peak performance reaches 8.1 petaflops. In our simulations of galaxy mergers, self-gravity calculations are accelerated using GPUs to enhance computational efficiency.
  
• Jul. 2, 2025
  Akifumi Takayama, a first-year master’s student, presented his study “Galaxy Collisions and Activity of Supermassive Black Holes” at the 8th Supermassive Black Hole Research Promotion Meeting held at the University of Tsukuba.
• Jun. 24, 2025
  Yuka Kaneda, a third-year Ph.D. student, visited Prof. Andrea Ferrara at Scuola Normale Superiore in Pisa, Italy, where she presented a seminar on our latest research findings.
• Jun. 23, 2025
  A joint research meeting was held at the University of Tokyo's Kashiwa Campus with Yohei Miki, Misa Yamaguchi (1st-yr, Ph.D. student), Akifumi Takayama (1st-yr, Master's student), and Yoshitomo Takahashi (1st-yr, Master's student). Following the meeting, we visited the supercomputer MIYABI, a collaborative development by the University of Tsukuba and the University of Tokyo.
  
  MIYABI recorded 46.80 PFLOPS on the TOP500 supercomputer performance ranking, making it the second-fastest research system in Japan, following RIKEN’s Fugaku. It plays a crucial role in our group’s investigations of galaxy evolution, black hole activity, and dark matter halos.
  

  
• Jun. 22, 2025
  As a recreational event, we enjoyed a sport climbing session for the first time in a while. With the participation of new members, it was a wonderful opportunity to strengthen ties not only within our team but also with colleagues from the broader theoretical astrophysics group.
  

  
  A total of 11 members joined — six with prior experience and five trying it for the first time. In a friendly and supportive atmosphere, we challenged both bouldering and top-rope routes. Arriving at the climbing gym around noon, we ended up staying past 7 p.m., fully absorbed in the experience.
• Jun. 16-20, 2025
  Yuka Kaneda (3rd-yr, Ph.D. student) delivered a presentation on our research findings at the international conference “Dancing in the Dark: When Galaxies Shape Galaxies,” held in Sexten, Italy.
• May 31-Jun. 4, 2025
  We visited Zhejiang University (Hangzhou, China) to conduct collaborative research discussions with Dr Go Ogiya (Ph.D. 2014), focusing on recent progress and future plans.
  

  

  The visit to Zhejiang University—surrounded by natural beauty and an expansive campus—was a highly valuable and stimulating experience. Dr. Go Ogiya, our first doctoral graduate, is currently serving as a tenure-track professor at the university. A highlight of the visit was the engaging research presentations and discussions with his graduate students, Junnan Shen and Zhihao Yin (2nd-yr, Master's student).

• May 30, 2025
  Misa Yamaguchi (1st-yr, Ph.D. student) has been awarded a fellowship under the JST Next Generation Researcher Challenging Research Program (SPRING). She will receive financial support for both her research and living expenses. Congratulations!
• May 26-30, 2025
  I participated in the international conference “Expanding the Boundaries of Dark Matter Halo,” held at Shanghai Jiao Tong University (Program), where recent results from our joint study with Michi Shinozaki (first year master’s student), Yuka Kaneda (third year Ph.D. student), and Kohei Hayashi (Sendai KOSEN), titled “Understanding the Cusp to Core Transition and the Characteristic Radius in Dark Matter Halos,” were presented.
  

  

  
• May 26-30, 2025
  Yuka Kaneda (3rd-yr, Ph.D. student) delivered a presentation titled “Split Stellar Streams as a Detector of Dark Satellites and Wandering Black Holes” at the international workshop “Galaxy Formation + AGORA in Asia 2025,” held at Osaka University’s Nakanoshima Center.
• May 24, 2025
  The paper titled “Simultaneous Formation of the Andromeda Giant Southern Stream and the Substructures in the Andromeda Halo,” co-authored by Misa Yamaguchi (1st-yr, Ph.D. student), Takanobu Kirihara (Kitami Institute of Technology), Yohei Miki (University of Tokyo), Itsuki Ogami (NAOJ), Masashi Chiba (Tohoku University), Yutaka Komiyama (Hosei University), and Mikito Tanaka (Hosei University), has been published in PASJ. [PASJ]
• May 21, 2025
  The team grew to 13 members in 2025, and although a bit late, we finally had a welcome party to celebrate the new arrivals.
• May 14-16, 2025
  At the “Bigdata Astronomy 2025” workshop held at the University of Tsukuba, Yuka Kaneda (3rd-yr, Ph.D. student) presented her work titled “Estimating Dark Matter Halo Density Profiles from Stellar Streams Using Convolutional Neural Networks” and Misa Yamaguchi (1st-yr, Ph.D. student) presented her research titled “Simultaneous Formation of the Four Substructures in the Andromeda Halo.”
• May 12, 2025
  Our proposed project “Galaxy Collisions and the Evolution of the Galactic Habitable Zone” has been accepted as a 2025 NAOJ Astrobiology Center Project. All formal procedures have been completed.
• May 11, 2025
  The annual joint BBQ of the theoretical and observational astrophysics groups at the University of Tsukuba was held at "Yukari-no-Mori."
  
• May 1, 2025
  In 2025, I started a new challenge in sports science research. Building on our expertise in astrophysical fluid dynamics, I am exploring its potential applications to athletic performance and biomechanics.
• Apr. 28, 2025
  One of our undergraduate thesis students has chosen to pursue research through analytical approaches rather than numerical simulations. While this path may not produce the visually striking figures often seen in simulation work, it offers a powerful way to understand complex cosmic phenomena by tracing them back to fundamental physical processes — and can lead to deeply meaningful insights.
• Apr. 21, 2025
  All first-year students have now finalised their research topics. In our group, we emphasise thorough discussions to ensure that each topic is well-matched to the student’s interests and abilities.
• Apr. 1, 2025
  With the beginning of the new academic year, we have welcomed the following individuals to our team: as first-year students in the Master’s Programme — Kanta Aimoto, Mayuka Oda, Michi Shinozaki, Yoshitomo Takahashi, and Akifumi Takayama; and as undergraduate thesis students — Maria Arima, Taisei Nomura, and Kenta Hagiwara.