Revealing the dark matter halo with axion direct detection

Journal Article · 13 June 2018 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.97.123006 · OSTI ID:1541173

Foster, Joshua W. ^[1]; Rodd, Nicholas L. ^[2]; Safdi, Benjamin R. ^[3]

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1. University of Michigan, Ann Arbor, MI (United States); DOE/OSTI
2. Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)
3. University of Michigan, Ann Arbor, MI (United States)

The next generation of axion direct-detection experiments may rule out or confirm axions as the dominant source of dark matter. Here we develop a general likelihood-based framework for studying the time-series data at such experiments, with a focus on the role of dark matter astrophysics, to search for signatures of the QCD axion or axionlike particles. Here we illustrate how in the event of a detection the likelihood framework may be used to extract measures of the local dark matter phase-space distribution, accounting for effects such as annual modulation and gravitational focusing, which is the perturbation to the dark matter phase-space distribution by the gravitational field of the Sun. Moreover, we show how potential dark matter substructure, such as cold dark matter streams or a thick dark disk, could impact the signal. For example, we find that when the bulk dark matter halo is detected at 5σ global significance, the unique time-dependent features imprinted by the dark matter component of the Sagittarius stream, even if only a few percent of the local dark matter density, may be detectable at ~2σ significance. A corotating dark disk, with lag speed ~50 km/s, that is ~20% of the local dark matter density could dominate the signal, while colder but as-of-yet unknown substructure may be even more important. Our likelihood formalism, and the results derived with it, are generally applicable to any time-series-based approach to axion direct detection.

• Research Organization: Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: SC0013999
• OSTI ID: 1541173
• Report Number(s): LCTP-17-08; MIT-CTP 4964
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 12 Vol. 97; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English