The possibility of dark matter being a particle involved in the generation of neutrino mass has been of interest for over 25 years. Sterile neutrinos—or in the contemporary parlance—dark fermions, are among the simplest and most cited particles which can provide a mechanism for neutrino mass. If one particle of this class has a small mixing, it can be quasi-thermally or nonthermally produced in the early Universe, affect cosmological structure formation, and be detected by X-ray telescopes or laboratory nuclear experiments. A candidate line was detected in 2014, and I review the status of the line and its implications for galaxy formation, proposals for future observations, and laboratory detection.
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Can Neutrino Self-interactions Save Sterile Neutrino Dark Matter?
Sterile neutrinos only interact with the standard model through the neutrino sector, and thus represent a simple dark matter (DM) candidate with many potential astrophysical and cosmological signatures. Recently, sterile neutrinos produced through self-interactions of active neutrinos have received attention as a particle candidate that can yield the entire observed DM relic abundance without violating the most stringent constraints from X-ray observations. We examine consistency of this production mechanism with the abundance of small-scale structure in the universe, as captured by the population of ultrafaint dwarf galaxies orbiting the Milky Way, and derive a lower bound on the sterile-neutrino particle mass of 37 keV. Combining these results with previous collider and X-ray limits excludes 100% sterile-neutrino DM produced by strong neutrino self-coupling, mediated by a heavy (≳1 GeV) scalar; however, data permits sterile-neutrino DM production via a light mediator.
more » « less- NSF-PAR ID:
- 10451613
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal Letters
- Volume:
- 954
- Issue:
- 1
- ISSN:
- 2041-8205
- Format(s):
- Medium: X Size: Article No. L18
- Size(s):
- ["Article No. L18"]
- Sponsoring Org:
- National Science Foundation
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