Title: Implications of a 21-cm signal for dark matter annihilation and decay

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. Yet, 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 findings allow mapping any future measurement of the global 21-cm signal into constraints on dark matter annihilation and decay, within the broad range ofmore » scenarios we consider.« less

Authors:

Liu, Hongwan ^[1]; Slatyer, Tracy R.  ^[1]

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+ Show Author Affiliations

1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Publication Date:

2018-07-02

Research Org.:

Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP)

OSTI Identifier:

1596604

Alternate Identifier(s):

OSTI ID: 1458594

Report Number(s):

MIT-CTP/4996
Journal ID: ISSN 2470-0010; PRVDAQ; arXiv:1803.09739

Grant/Contract Number:  

SC0013999; SC0012567

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review D

Additional Journal Information:

Journal Volume: 98; Journal Issue: 2; Journal ID: ISSN 2470-0010

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; dark matter; particle dark matter; radio, microwave, & sub-mm astronomy