Analysis of production mechanisms of the axion dark matter based on numerical simulation

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03640
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: High Energy Accelerator Research Organization (2019-2020); The University of Tokyo (2018)
• Principal Investigator: Sekiguchi Toyokazu 大学共同利用機関法人高エネルギー加速器研究機構, 素粒子原子核研究所, 研究員 (30584750)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 暗黒物質 / 素粒子宇宙論 / 観測的宇宙論 / アクシオン / 位相欠陥

Outline of Final Research Achievements

Focusing on the possibility of axion dark matter, we have investigated a variety of its cosmological aspects, including its generation processes, time evolution afterwards, and observability in the present universe. Regarding the generation processes from axion topological defects such as comic strings, we have successfully derived novel implications based on the state-of-the-art massively parallel simulations. In particular, we have shown that axion cosmic strings have a long-term dynamics, which have innovated the previous picture of the cosmic strings. In addition, we have developed an innovative numerical simulation method of the axion electrodynamics and investigated its cosmological applications. We also have studied probing axion dark matter scenario with 21cm line observations. Our study have improved our understanding of axion cosmology extensively.

Free Research Field

宇宙論

Academic Significance and Societal Importance of the Research Achievements

暗黒物質の正体は宇宙・素粒子分野における最大の謎であり、その正体を明らかにすることで未知の物理への足掛かりが得られると期待されている。様々な暗黒物質候補の中で、アクシオンは最有力候補の一つであり、その直接検出のために様々な実験が世界中で進行・計画されている。他方、アクシオン暗黒物質の主要な生成過程であるアクシオン位相欠陥からのアクシオン放出には大きな理論的不定性があり、検出実験を計画する上で大きな問題となっている。我々は世界最大規模の第一原理数値シミュレーションに基づきアクシオン位相欠陥のダイナミクスにおける未知の性質を明らかにし、更なる理論予言の発展を導いた。