Implications of a 21-cm signal for dark matter annihilation and decay
Name
PhysRevD.98.023501.pdf
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2.35 MB
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Adobe PDF
Checksum (MD5)
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Author(s)
Liu, Hongwan
Slatyer, Tracy Robyn
Date Issued
July 2018
Journal
Physical Review D
Publisher
American Physical Society
Citation
Liu, Hongwan and Tracy R. Slatyer. "Implications of a 21-cm signal for dark matter annihilation and decay." Physical Reveiw D 98, 2 (July 2018): 023501 © 2018 American Physical Society
Version
Final published version
Abstract
Measurements of the temperature of the baryons at the end of the cosmic dark ages can potentially set very precise constraints on energy injection from exotic sources, such as annihilation or decay of the dark matter. However, additional effects that lower the gas temperature can substantially weaken the expected constraints on exotic energy injection, whereas additional radiation backgrounds can conceal the effect of an increased gas temperature in measurements of the 21-cm hyperfine transition of neutral hydrogen. Motivated in part by recent claims of a detection of 21-cm absorption from z∼17 by the EDGES experiment, we derive the constraints on dark matter annihilation and decay that can be placed in the presence of extra radiation backgrounds or effects that modify the gas temperature, such as dark matter (DM)–baryon scattering and early baryon-photon decoupling. We find that if the EDGES observation is confirmed, then constraints on light DM decaying or annihilating to electrons will in most scenarios be stronger than existing state-of-the-art limits from the cosmic microwave background, potentially by several orders of magnitude. More generally, our results allow mapping any future measurement of the global 21-cm signal into constraints on dark matter annihilation and decay, within the broad range of scenarios we consider.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevD.98.023501
