A Selective Survey of Ideas, Tools and Results in Constructive Field Theory

2024年2月26日(月) 13:00 - 14:30

クリスティ・コウジ・ケリー (数理創造プログラム 基礎科学特別研究員)

In this talk we discuss some aspects of constructive field theory with an emphasis on analytical and probabilistic methods and results. In particular after an overview of some points in the history of constructive QFT we plan to discuss some early achievements in axiomatic QFT, some features of the theory of distributions and the basic structure of the Wightman reconstruction theorem. We also introduce the Osterwalder-Schrader axioms and overview the strategy for the construction of nontrivial measures describing path-integrals for interacting QFTs. Depending on time constraints we might also discuss probabilistic tools (weak convergence of measures, the Bochner-Minlos theorem etc), Gaussian measures, UV regularity of simple QFTs and the construction of (infinite volume) Euclidean P(phi)_2 measures. The plan is to discuss some of these topics in some detail after the end of the official seminar.

会場: via Zoom / セミナー室 (359号室)

イベント公式言語: 英語

Second Workshop on Fundamentals in Density Functional Theory (DFT2024)

2024年2月20日(火) - 22日(木)

The density functional theory (DFT) is one of the powerful methods to solve quantum many-body problems, which, in principle, gives the exact energy and density of the ground state. The accuracy of DFT is, in practice, determined by the accuracy of an energy density functional (EDF) since the exact EDF is still unknown. Currently, DFT has been used in many communities, including nuclear physics, quantum chemistry, and condensed matter physics, while the fundamental study of DFT, such as the first principle derivations of an accurate EDF and methods to calculate many observables from obtained densities and excited states. However, there has been little opportunity to have interdisciplinary communication. On December 2022, we had the first workshop on this series (DFT2022) at Yukawa Institute for Theoretical Physics, Kyoto University, and several interdisiplinary discussions and collaborationd were started. To share such progresses and extend collaborations, we organize the second workshop. In this workshop, the current status and issues of each discipline will be shared towards solving these problems by meeting together among researchers in mathematics, nuclear physics, quantum chemistry, and condensed matter physics. This workshop mainly comprises lectures/seminars on cutting-edge topics and discussion, while a half-day session composed of contributed talks is also planned. This workshop is partially supported by iTHEMS-phys Study Group. This workshop is a part of the RIKEN Symposium Series. The detailed information can be found in the workshop website.

会場: 融合連携イノベーション推進棟（IIB） 8階 (メイン会場) / via Zoom

イベント公式言語: 英語

An introduction to the exact WKB analysis via the hypergeometric differential equation

2024年2月19日(月) - 22日(木)

青木 貴史 (近畿大学 理工学部 名誉教授)

This is an introductory course to the exact WKB analysis. Firstly we review some basic facts concerning formal power series and WKB solutions. Secondly we give an overview of the connection formulas for WKB solutions to ordinary differential equations of second order with a large parameter. Next, after recalling some classical theory for the Airy equation and the Gauss hypergeometric differential equation, we show how the exact WKB analysis is used for these equations and what are obtained. One of the main results to be presented in this course is the relation the between the classical hypergeometric function and the Borel resummed WKB solutions to the hypergeometric differential equation with a large parameter. Some applications and recent topics are also given. [Schedule (Tentative)] Day 1 10:00 - 11:30 Lecture 1 14:00 - 16:00 Lecture 2 Day 2 10:00 - 11:30 Lecture 3 14:00 - 16:00 Lecture 4 Day 3 10:00 - 11:30 Lecture 5 14:00 - 16:00 Lecture 6 Day 4 10:00 - 11:30 Lecture 7 14:00 - 16:00 Lecture 8

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

Cellular-level left-right asymmetry, cell chirality, induces the chiral collective rotation of multicellular colony

2024年2月15日(木) 16:00 - 17:00

石橋 朋樹 (理化学研究所 生命機能科学研究センター (BDR) フィジカルバイオロジー研究チーム 基礎科学特別研究員)
西澤 凌平 (大阪大学 大学院生命機能研究科 博士課程)

The left-right (LR) asymmetric morphology of organs is essential for the development and maintenance of their functions in various species. In recent years, it has become clear that the LR asymmetry of organs originates from cell chirality, the LR asymmetric nature at the cellular level [1]. However, it is unclear how the cell chirality generates the LR asymmetry at the multicellular level. Here we show a mechanism of LR asymmetry formation at the multicellular level based on cell chirality. We previously found that Caco-2 cells, a typical cultured epithelial cell line derived from human colon cancer, exhibit stereotypical and directional cell chirality; when Caco-2 cells are cultured as single cells, their nuclei and cytoplasm rotate in the clockwise direction at a rate of 50°/h [2]. Interestingly, when Caco-2 forms multicellular colonies, the colonies also undergo a collective clockwise rotation at 10º/h. We revealed that the actomyosin cytoskeleton is essential for the formation of the collective rotation [2]. We also found that Caco-2 cells formed lamellipodia and focal adhesions LR asymmetrically during the collective colony rotation, which may be responsible for the chiral collective motion. Interestingly, the disruption of microtubules reversed the direction of collective rotation. The LR asymmetric formation of lamellipodia and focal adhesions was also reversed by inhibition of microtubule polymerization. We will discuss the possible mechanism and the mathematical model where cell chirality induces multicellular chiral rotation depending on microtubules.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

Chemical reaction network theory and the problem of reaction rate

2024年2月8日(木) 16:00 - 17:00

須田 智晴 (理化学研究所 環境資源科学研究センター (CSRS) 生体機能触媒研究チーム 特別研究員)

A chemical system can be described at different levels. When we focus on the population of chemical species, it is convenient to consider the system as consisting of a number of chemical reactions, which assumes the structure of a (hyper)graph together with the species. The chemical reaction network theory studies chemical systems described in such a way. It aims to elucidate the dynamics of overall chemical composition in terms of the associated graph structure. Notably, it applies not only to chemical systems but also to more general systems as long as the mathematical structure is compatible. In the first part of this talk, we will review the basic concepts and results of the theory, which mainly concern the existence and stability of the equilibrium. From the viewpoint of chemical kinetics, it is interesting to consider the rate of the overall reaction, which may be obtained by the total balance of chemical species. The second part of the talk will be devoted to this topic. Formulation of the problem and some results will be presented. In particular, chemical reaction networks with first-order reactions will be considered in detail.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Relativistic Jet Simulations and Modeling on Horizon Scale

2024年2月8日(木) 13:00 - 14:30

水野 陽介 (T.D. Lee Fellow / Associate Professor, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, China)

Relativistic jets are launched in the vicinity of the central black holes and emit powerful radiation across the electromagnetic spectrum. According to our current understanding, relativistic jets are launched by directly tapping the rotational energy of spinning black holes via the so-called Blandford-Znajek process. In addition to the spin of the black hole, numerical simulations showed the amount of accreted magnetized flux has a major impact on the formation of relativistic jets. We have investigated the radiative signatures of self-consistently launched relativistic jets using 3D general relativistic magneto-hydrodynamical simulations and general relativistic radiative transfer calculations in horizon scale to the connection with large-scale structure. We discuss our findings and comparison with observations.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

Recent advances in nuclear Density Functional Theory and applications to the nuclear response

2024年2月6日(火) 13:30 - 15:00

ジャンルカ・コロ (Professor, Department of Physics, University of Milan, Italy / Professor, Sezione di Milano, INFN, Italy)

In this contribution, I will give an overall (and, of course, biased) view of the general status of DFT. I will stress that, in contrast to ab initio methods, DFT is the only framework that allows the study of excited states, including those lying at relatively high energy. Accordingly, I will focus on the nuclear response. After a reminder on the nuclear Giant Resonances and the link with the nuclear equation of state, I will discuss the projection methods to restore symmetries in the calculations of deformed systems. While symmetry-restored calculations are nowadays of common use in the study of ground-state properties and low-lying excitations, similar realistic investigations for the nuclear response are essentially missing in the literature. Recently, we have implemented an exact Angular Momentum Projection (AMP) on top of Skyrme-Random Phase Approximation (RPA) calculations in a projection after variation (PAV) scheme, for the first time. The results will be critically analysed in the case of the monopole response, also taking into account the experimental investigations that can be envisioned for well-deformed systems. If time allows, the nuclear response will be also discussed as a way to improve the current density functionals and ground them on ab initio nuclear theory. This seminar is co-hosted by Nuclear Many-body Theory Laboratory and Few-body Systems in Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science.

会場: 理化学研究所 和光キャンパス RIBF棟 2階 大会議室 (メイン会場) / via Zoom

イベント公式言語: 英語

Nuclear Energy-Density Functional Approach to Bridging Neutron-Rich Nuclei and Neutron Stars

2024年2月5日(月) 13:30 - 15:00

吉田 賢市 (大阪大学 核物理研究センター 准教授)

Understanding the properties of neutron-rich nuclei has been a central subject in low-energy nuclear physics. The great interest lies not only in the pursuit of a variety of structures and the elucidation of the mechanisms of their occurrence but also in obtaining insights into the structure of the inner crust of neutron stars. With advances in neutron-star observation techniques, the structure of neutron stars has been becoming better understood. The data accumulated from these observations unveil properties of neutron-rich matter that are otherwise inaccessible through terrestrial experiments. In this talk, I will introduce an attempt to construct a nuclear energy-density functional (EDF) inspired by the observations and then demonstrate its applicability to nuclear structure problems, including mass and deformation. One intriguing aspect of neutron stars is the emergence of superfluidity, especially the occurrence of spin-triplet pairing. I will discuss the unconventional pairing in nuclei within the nuclear EDF framework and give perspectives on the study of the phase diagram of the superfluidity in neutron stars. This seminar is co-hosted by UKAKUREN.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

第三回 社会課題は数理科学で解決できる!? − 企業における数理研究 −

2024年2月3日(土) 13:00 - 17:00

昨年度に引き続き、数理科学研究による社会課題の解決の可能性を探るシンポジウムを開催します。過去2年は「数理研究の社会実装一課題と克服」「企業課題と数理研究をつなぐ」というテーマで行いました。今年度は、具体例に目を向けて、「企業における数理研究」のタイトルを設定し、企業における数理を用いた活動について紹介をいただくことを目的としています。そこで、現在、企業で数理を使った活動をされている研究者、あるいはかつて企業で数理研究をして大学に研究の場を移された研究者など、多様な経歴をお持ちの先生方に講演をお願いしています。くわえて、近年は数学の大学院生企業活動と結びつける活動も数多く行われています。こうした活動も参加者のみなさんと共有することで、今後の企業連携を通した社会課題の数理科学のあり方について意見交換をするパネルセッションを行います。このような活動に興味のある企業研究者や数理科学者の皆様の積極的な参加を心よりお待ちしています。 主催： JST未来社会創造事業「共通基盤」領域 本格研究課題　未来医療を創出する4次元トポロジカルデータ解析数理基盤の開発 共催： 九州大学 マス・フォア・インダストリ研究所 理化学研究所iTHEMS 後援： 株式会社 理研数理 京都大学 大学院理学研究科 附属サイエンス連携探索センタ−(SACRA) コーディネート： 名古屋大学大学院 理学研究科 生命理学専攻 異分野融合生物学研究室/iBLab 詳細は、関連リンクをご覧下さい。

会場: 名古屋大学 野依記念学術交流館とZoomのハイブリッド開催

イベント公式言語: 日本語

Competition across scales in biology

2024年1月31日(水) 11:00 - 12:00

シダルタ・ゴヤル (Associate Professor, Department of Physics, University of Toronto, Canada)

Many biological phenomena emerge from interaction and competition between its parts. I will share some examples across biological scales where data-driven theory can reveal new rules of biological competition. At the molecular scale competition between mitochondrial genomes within budding yeast depends on genome architecture; dynamics of adaptive immunity in microbes reveal different modalities of competition and coexistence of bacteria and its phages; in mammals cellular reprogramming may be driven by elite clones, and tumor response to drugs is driven by "epigenetic" switching. Going beyond, I will present some ideas on understanding dynamical systems that govern cell fate dynamics and if competition may play a role in it. Short bio: Sidhartha Goyal got his PhD in Physics at Princeton in 2009 and then moved to Kavli Institute for Theoretical Physics, Santa Barbara for a postdoc. He got his first degree in Electrical Engineering from IIT Bombay. He is now an Associate Professor in the Physics Department at University of Toronto interested in collective phenomena in biology across scales.

会場: via Zoom

イベント公式言語: 英語

“Quantum-like Modeling” in Biology, Cognitive & Social Sciences

2024年1月26日(金) 9:30 - 17:00

近年、開放量子系(Open Quantum System)として生物・認知・社会現象をとらえて、それらの背後に潜む基本原理をいわゆる『Quantum-Like Modeling』をとおして数理的に定義することによって、これまで定性的な記述的論理構築に留まっていた現象を、厳密な定量解析の対象としようとする気運が熟そうとしている。そこで、関連する各分野での先端的な挑戦に着手している研究者による話題提供(15 分程度)と、数名の指定討論者によるコメント(5 分程度)を皮切りとした、参加者全員による自由闊達なブレーンストーミング(30 分程度)を企画した。各セッションでは、下記の様なごくおおまかな展望のもとに、参加者それぞれの研究の将来の発展可能性を大胆に広く探るような、胸躍る議論を期待したい。 プログラム 09:30~10:00 導入・背景(入來篤史・初田哲男) 導入1：開催趣旨(入來)−量子認知、Open Quantum System の黎明 導入2：RIKEN Quantum(初田)−量子計算の現状と展望 10:10~11:00 量子的現象(⻄郷甲矢人)：討論―小澤、江守 話題：JST-CREST 課題を中心に Open Quantum System 全体の概観を解説 討論：量子論的数理を用いた一般現象のモデリング・解釈の可能性と期待 11:10~12:00 新しい数学(小澤正直)：討論―小谷、初田 話題：非可換な順序効果の理論とブレークスルーにおける新しい数学理論 討論：実験家と数学者との相補的共働のデザインと「新しい数学」の創造 (昼休み) 13:30~14:20 生物学考察(磯村拓哉)：討論―桜田、石川 話題：ベイズ推論変分自由エネルギー原理における経路積分的手法 討論：生物学・脳神経科学・認知科学と精神医学における量子論的解釈 14:30~15:20 人文社会科学(田中彰吾)：討論―大村、池田 話題：原子論的人間観から量子メタファーによる人間と社会の理解へ 討論：人文社会科学における量子的現象と量子計算の社会実装の可能性 15:50~17:00 総合討論(司会・話題提供：入來篤史) 話題：「人間現象」の進化/歴史の経路積分・量子論的解釈と Quantum-Like Modeling 討論：フリー ブレーン ストーミング 登壇者(登壇順) 入來篤史 (CREST マルチセンシング領域 研究総括/理研 未来戦略室) 初田哲男 (理研 数理創造プログラム(iTHEMS)/CREST マルチセンシング領域 アドバイザー) ⻄郷甲矢人 (CREST マルチセンシング領域/⻑浜バイオ大学 フロンティアバイオサイエンス学科) 小澤正直 (理研 未来戦略室/中部大学 創発学術院 AI 数理データサイエンスセンター) 江守陽規 (理研 未来戦略室/北海道大学 工学部 光エレクトロニクス研究室) 小谷元子 (理研 数理創造プログラム(iTHEMS)/東北大学 理学部 数学科) 磯村拓哉 (CREST マルチセンシング領域/理研 脳神経科学研究センター 脳型知能理論研究ユニット) 桜田一洋 (AMED-CREST マルチセンシング領域 アドバイザー/理研 情報統合本部/慶應義塾大学医学部) 石川哲朗 (理研 情報統合本部 医療データ数理推論チーム/慶應義塾大学医学部 拡張知能医学講座) 田中彰吾 (CREST マルチセンシング領域/東海大学 文明研究所) 大村敬一 (放送大学 教養学部) 池田裕一 (京都大学 総合生存学館)

会場: 大河内記念ホール (メイン会場) / via Zoom

イベント公式言語: 日本語

Quantum Enhancement in Dark Matter Detection with Quantum Computation

2024年1月22日(月) 16:00 - 18:00

Thanaporn Sichanugrist (東京大学 大学院数理科学研究科 博士課程)
陳 詩遠 (東京大学 素粒子物理国際研究センター (ICEPP) 特任助教)

Title: Wave-like Dark Matter Search Using Qubits Abstract: The rapid controllability required for quantum computers makes the currently proposed quantum bit modalities also attractive as electromagnetic field sensors. One of the promising applications is wave-like dark matter searches, where the electric field converted from the coherent dark matter excites the qubits, leading to detectable signals [Phys. Rev. Lett. 131, 211001]. The quantum coherence between the qubits can be utilized to enhance the signal rate in a multi-qubit system. By designing an appropriate quantum circuit to entangle the qubits, it was found that the signal rate can scale proportionally to $n_q^2$, with $n_q$ being the number of sensor qubits, rather than linearly with $n_q$ [arXiv: 2311.10413]. In the seminar, we overview the theoretical framework of the search, elaborate on the signal-enhancing mechanism driven by quantum entanglement with specific examples of the quantum circuits, and discuss how the scheme can be implemented in the platform of future fault-tolerant quantum computers. We also provide the introduction of the experimental realization, and report the status of the experimental works carried out in UTokyo/ICEPP.

会場: via Zoom

イベント公式言語: 英語

Knot Theory in Doubly Periodic Tangles and Applications

2024年1月19日(金) 15:00 - 16:30

ソニア・マムーディ (東北大学 材料科学高等研究所 (AIMR) 数学連携グループ 助教)

Doubly periodic entangled structures offer an interesting framework for modeling and investigating diverse materials and physical phenomena, from micro to large scales. Specifically, a doubly periodic tangle (DP tangle) is characterized as an embedding of an infinite number of curves in the thickened plane, derived as the lift of a link in the thickened torus to the universal cover. DP tangles play a crucial role in scientific research, particularly in fields such as materials science, molecular chemistry, and biology. Despite their widespread applications, a universally accepted mathematical description of DP tangles is currently lacking. One of the key challenges arises from the infinite possibilities in choosing a periodic cell (referred to as a motif) for a DP tangle, taking into account various periodic boundary conditions. In this presentation, we conduct a comprehensive examination of the concept of topological equivalence of DP tangles, offering insights into potential classifications and applications in the process.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Quantum features in cosmological perturbations?

2024年1月18日(木) 14:15 - 15:00

アモリ・ミケリ (数理創造プログラム 特別研究員)

The statistical properties of the CMB anisotropies, reflecting the curvature inhomogeneities in the very early Universe, are very well accounted for by assuming that the inhomogeneities come from amplified vacuum fluctuations. This scenario makes the cosmological perturbations a possible observational window on the interplay between quantum degrees of freedom and gravity. I will review the discussions on the current presence or absence of quantum features in the perturbations, emphasising the quantum information approaches to this question, and comment on the observability of these features.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Gravitational lensing on superposed curved spacetime

2024年1月18日(木) 13:30 - 14:15

郭 優佳 (名古屋大学 大学院理学研究科 博士課程)

In 2017, Bose et al. proposed a tabletop experiment to observe the gravitational effect induced by a spatially superposed mass source, particularly gravity-induced entanglement. This experiment is expected to be the first step in exploring the quantum nature of gravity. Also, there are ongoing efforts to extend their proposal to the relativistic region to observe the unique quantum nature of gravity. In this talk, I will investigate gravitational lensing in a weak gravitational field induced by a spatially superposed mass source. I will show the Einstein ring image of a quantum scalar field propagated on a superposed curved spacetime and compare it with the image of the semi-classical gravity case. This work is currently in progress and is a collaboration with Yasusada Nambu.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Bayesian mechanics of classical, neural, and quantum systems

2024年1月17日(水) 16:30 - 17:45

磯村 拓哉 (理化学研究所 脳神経科学研究センター (CBS) 脳型知能理論研究ユニット ユニットリーダー)

(This is a joint seminar with iTHEMS Biology group.) Bayesian mechanics is a framework that addresses dynamical systems that can be conceptualised as Bayesian inference. However, the elucidation of requisite generative models is required for empirical applications to realistic self-organising systems. This talk introduces that the Hamiltonian of generic dynamical systems constitutes a class of generative models, thus rendering their Helmholtz energy naturally equivalent to variational free energy under the identified generative model. The self-organisation that minimises the Helmholtz energy entails matching the system's Hamiltonian with that of the environment, leading to an ensuing emergence of their generalised synchrony. In short, these self-organising systems can be read as performing variational Bayesian inference of the interacting environment. These properties have been demonstrated with coupled oscillators, simulated and living neural networks, and quantum computers. This notion offers foundational characterisations and predictions regarding asymptotic properties of self-organising systems exchanging with the environment, providing insights into potential mechanisms underlying emergence of intelligence.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

Methods for neural decoding using machine learning, deep learning, and quantum-inspired algorithms

2024年1月17日(水) 15:00 - 16:15

間島 慶 (量子科学技術研究開発機構 (QST) 研究員)

Note: The format of this event has changed from hybrid to Zoom only. However, you will still be able to watch it on the screen in Room #359 of the Main Research Building. (This is a joint seminar with iTHEMS Biology group.) Recent advances in machine learning have enabled the extraction of intrinsic information from neural activities, a field known as neural decoding. In this presentation, I will introduce several machine learning methods recently developed for neural decoding analysis: 1) a method for visualizing subjective images in the human mind based on brain activity [1], 2) a supervised algorithm designed for predicting discrete ordinal variables [2], and 3) a fast classical algorithm algorithm inspired by quantum computation for approximating principal component analysis (PCA) and canonical correlation analysis (CCA), potentially allowing for the analysis of vast-dimensional neural data [3]. Following these presentations, I am eager to engage in discussions with participants at the RIKEN Quantum Seminar regarding potential collaborations.

会場: via Zoom

イベント公式言語: 英語

Dust-driven instabilities in protoplanetary disks: toward understanding formation of planetesimals

2024年1月17日(水) 10:30 - 11:30

冨永 遼佑 (理化学研究所 開拓研究本部 (CPR) 坂井星・惑星形成研究室 基礎特別研究員)

Planet formation starts from collisional growth of sub-micron-sized dust grains in a gas disk called a protoplanetary disk. They are expected to grow toward km-sized objects called planetesimals. The resulting planetesimals further coalesce by gravity and form planets. However, there are some barriers preventing planetesimal formation, which includes fast radial drift and collisional fragmentation of dust grains. To circumvent the barriers and to explain planetesimal formation, previous studies have proposed hydrodynamic instabilities of dusty-gas disks. The instabilities can cause dust clumping, and planetesimals form if the resulting clumps collapse self-gravitationally. We have been investigating the linear/nonlinear development of these dust-gas instabilities. We also found a new instability driven by collisional growth of dust, which can bridge a potential gap between the first dust growth and the later planetesimal formation via the previous instabilities. In this talk, I will introduce our work on the dust-driven instabilities and their impact on planetesimal formation.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Does horizontal gene transfer stabilize cooperation in bacteria?

2024年1月16日(火) 16:00 - 17:00

Anna Dewar (Postdoctoral Researcher, Department of Biology, University of Oxford, UK)

Bacteria are highly social. Much of this sociality occurs through the production of cooperative ‘public goods’. Unlike in animals, bacterial genes are able to transfer horizontally between individuals, in addition to vertically via descendants. This widespread horizontal gene transfer has implications for the concept of relatedness and how cooperation is maintained in bacteria. It has been suggested that horizontal gene transfer, particularly via small segments of DNA called plasmids, could stabilize cooperation in bacteria. Transfer of a cooperative gene could turn non-cooperative ‘cheats’ into cooperators, preventing cheats from invading and destabilizing cooperation. We tested this with a comparative analysis across bacterial species. In contrast to the predictions of the hypothesis, we found that genes for cooperative traits were not more likely to be carried on either: (1) plasmids compared to chromosomes; or (2) plasmids that transfer at higher rates. Our results were supported by theoretical modelling which showed that, while horizontal gene transfer can help cooperative genes initially invade a population, it has less influence on the longer-term maintenance of cooperation.

会場: via Zoom

イベント公式言語: 英語

Probing structure of neutron stars through X-ray bursters

2024年1月12日(金) 14:00 - 15:15

土肥 明 (理化学研究所 開拓研究本部 (CPR) 長瀧天体ビッグバン研究室 基礎科学特別研究員)

Type-I X-ray bursts are rapidly brightening phenomena triggered by the nuclear burning of light elements near the surface of accreting neutron stars. Most of the X-ray bursters show irregular behavior of light curves. However, some X-ray bursters are somehow quite regular, i.e., constant recurrence time and constant shaper of light curves, and are often called Clocked bursters, which are powerful sites to probe uncertainties of many model parameters such as accretion rate, the composition of accreted matter, reaction rates, neutron star structure, and temperature. In this study, we focus on the uncertainties of the equation of states, which determines the latter two properties. Based on our numerical models covering whole areas of neutron stars, we will present their impact on X-ray burst light curves. Furthermore, we will discuss the possibility of constraining the equation of states from Clocked bursters such as GS 1826-24 and 1RXS J180408.9-342058.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語