2021 Fiscal Year Annual Research Report
Astrophysical and Terrestrial Signals of Axion Stars
Publicly Offered Research
| Project Area | What is dark matter? - Comprehensive study of the huge discovery space in dark matter |
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| Project/Area Number |
21H05451
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| Research Institution | The University of Tokyo |
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Principal Investigator |
Eby Joshua 東京大学, カブリ数物連携宇宙研究機構, 特任研究員 (50902095)
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| Project Period (FY) |
2021-09-10 – 2023-03-31
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| Keywords | dark matter / axions / axion stars / terrestrial signals / astrophysical searches / axion bursts |
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| Outline of Annual Research Achievements |
We have made significant progress in understanding the signals which arise from axion stars. Building on work with colleagues at IPMU (now published, Phys. Lett. B825 (2022) 136858), I have been investigating the signals from collapsing axion stars which interact with photons or electrons inside of quantum sensor experiments; our analysis, nearly complete, shows a significant increase in the reach of direct detection experiments over a wide range of axion parameters. A second novel signal I have investigated arises from the build-up of high-energy axions over long astrophysical timescales, which can give rise to a 'background' of particles which can be searched for in the same experiments. We have also developed the framework to analyze photon signals from this axion background, which can arise due to axion interactions with intergalactic magnetic fields. These all provide novel and important signals for direct searches.
In another work, now in preprint, we investigated a new model of an axion-like particle which is connected to the Higgs hierarchy problem. This work provides a simple but promising new target for direct searches, including those described above.
Finally, we have developed a simple framework to understand the formation of axion bound states, which will appear in a completed research paper in the coming months.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The progress along the lines of this research proposal have been mostly smooth, and we have been able to propose a number of new search strategies to hasten the discovery of axion dark matter. New ideas, including the detection of axion bursts with quantum sensors, have arisen from these discussions in an unanticipated way, and provide exceptional sensitivity to these signals. The core of the project, which is the discovery of new signals from axion stars, has continued as planned.
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| Strategy for Future Research Activity |
We are finalizing the research papers related to (1) quantum sensors to detect axion bursts, (2) the axion background from the build-up of many bursts from axion stars, and (3) the formation of axion overdensities. The physics is well-understood at this point, and progress from here is expected to be very smooth as we write up the results.
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Research Products
(7 results)
