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Title: Severely Constraining Dark-Matter Interpretations of the 21-cm Anomaly

Here, the EDGES Collaboration has recently reported the detection of a stronger-than-expected absorption feature in the global 21-cm spectrum, centered at a frequency corresponding to a redshift of z≃17. This observation has been interpreted as evidence that the gas was cooled during this era as a result of scattering with dark matter. In this Letter, we explore this possibility, applying constraints from the cosmic microwave background, light element abundances, Supernova 1987A, and a variety of laboratory experiments. After taking these constraints into account, we find that the vast majority of the parameter space capable of generating the observed 21-cm signal is ruled out. The only viable models are those in which a small fraction, ~0.3%–2%, of the dark matter consists of particles with a mass of ~10–80 MeV and which couple to the photon through a small electric charge, roughly 10 –6–10 –4 as large as the electron charge. Furthermore, in order to avoid being overproduced in the early Universe, such models must be supplemented with an additional depletion mechanism, such as annihilations through a L μ–L τ gauge boson or annihilations to a pair of rapidly decaying hidden sector scalars.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [3]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Chicago, Chicago, IL (United States)
  3. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Publication Date:
Report Number(s):
arXiv:1803.02804; FERMILAB-PUB-18-066-A
Journal ID: ISSN 0031-9007; PRLTAO; 1658929
Grant/Contract Number:
AC02-07CH11359; AC02-76SF00515
Type:
Published Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 121; Journal Issue: 1; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1458596
Alternate Identifier(s):
OSTI ID: 1437302

Berlin, Asher, Hooper, Dan, Krnjaic, Gordan, and McDermott, Samuel D. Severely Constraining Dark-Matter Interpretations of the 21-cm Anomaly. United States: N. p., Web. doi:10.1103/PhysRevLett.121.011102.
Berlin, Asher, Hooper, Dan, Krnjaic, Gordan, & McDermott, Samuel D. Severely Constraining Dark-Matter Interpretations of the 21-cm Anomaly. United States. doi:10.1103/PhysRevLett.121.011102.
Berlin, Asher, Hooper, Dan, Krnjaic, Gordan, and McDermott, Samuel D. 2018. "Severely Constraining Dark-Matter Interpretations of the 21-cm Anomaly". United States. doi:10.1103/PhysRevLett.121.011102.
@article{osti_1458596,
title = {Severely Constraining Dark-Matter Interpretations of the 21-cm Anomaly},
author = {Berlin, Asher and Hooper, Dan and Krnjaic, Gordan and McDermott, Samuel D.},
abstractNote = {Here, the EDGES Collaboration has recently reported the detection of a stronger-than-expected absorption feature in the global 21-cm spectrum, centered at a frequency corresponding to a redshift of z≃17. This observation has been interpreted as evidence that the gas was cooled during this era as a result of scattering with dark matter. In this Letter, we explore this possibility, applying constraints from the cosmic microwave background, light element abundances, Supernova 1987A, and a variety of laboratory experiments. After taking these constraints into account, we find that the vast majority of the parameter space capable of generating the observed 21-cm signal is ruled out. The only viable models are those in which a small fraction, ~0.3%–2%, of the dark matter consists of particles with a mass of ~10–80 MeV and which couple to the photon through a small electric charge, roughly 10–6–10–4 as large as the electron charge. Furthermore, in order to avoid being overproduced in the early Universe, such models must be supplemented with an additional depletion mechanism, such as annihilations through a Lμ–Lτ gauge boson or annihilations to a pair of rapidly decaying hidden sector scalars.},
doi = {10.1103/PhysRevLett.121.011102},
journal = {Physical Review Letters},
number = 1,
volume = 121,
place = {United States},
year = {2018},
month = {7}
}