2022 Fiscal Year Research-status Report
Uncovering the Local Dark Matter Density in Axion Dark Matter Scenarios
| Project/Area Number |
21K20366
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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) |
2021-08-30 – 2024-03-31
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| Keywords | dark matter / axions / ultralight particles / astrophysics / axion stars / gravitational atoms |
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| Outline of Annual Research Achievements |
This project has been exceptionally fruitful for producing important results. The main results so far are that we have uncovered two novel experimental signatures of large-density clumps of dark matter in the solar system:
1) we proposed a space mission with on-board atomic clocks as a direct probe of small, dense bound states around the Sun which from from axions (published in Nature Astronomy, 7 (2023) 1, 113-121); and
2) we set a completely new constraint on the dark matter density in the solar system using high-precision asteroid tracking data (under review by Nature Astronomy).
These proposals prove that small-scale dark matter overdensities can be directly probed; in the future, it may be possible to expand on this work to precisely measure the dark matter density in the solar system.
We also have made significant progress in understanding the mechanism of formation of axion bound states, including those bound to the Sun. These bound states can significantly modify the local dark matter density and give rise to novel observables in experiment. Our mechanism will provide a precise experimental target for direct searches, both those conducted on Earth as well as future space missions.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
Aside from the achievements listed above, we have been working to understand the process by which axion overdensities form in the solar system, for example around the Sun. A research work along these lines is forthcoming very soon; we had expected it to be finalized by now, but delays related to the novel coronavirus led to slower-than-expected progress. We expect to finalize this important work in the coming months, where we show how interactions of axion particles in the vicinity of the Sun can lead directly to their capture and give rise to large dark matter densities in the solar system. Because this work is quite exciting and novel, we are taking great care to ensure our analysis is correct before publishing it.
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| Strategy for Future Research Activity |
We are finalizing our paper on the formation of axion bound states around the Sun, as mentioned above. The collaboration, which includes colleagues in Japan, US, Israel and Germany, is finally making rapid progress towards a final version of this work and we expect to release the paper in the coming months. I have begun to discuss this work with external colleagues and have presented preliminary results at a number of invited seminars, for example at KIAS in Seoul and in the US. The finished work, related to our proposed space mission and asteroid tracking constraint, have also been presented at a large number of seminars and workshops. The response from the community has been exceptionally positive, with many ideas for future developments in this blossoming subfield of dark matter research.
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| Causes of Carryover |
Due to some delays from collaborators in Israel (related to covid-19), an international visit to finalize the work had to be postponed, and as a result the funds were not able to be used during FY2022 as planned.
The remainder of the grant funds will be used to partially fund a visit to collaborators in Germany and Israel in May and June 2023, in order to hasten the completion of this work.
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Research Products
(8 results)
