Edges and Endpoints in 21-cm Observations from Resonant Photon Production.

Area of Science:

• Cosmology
• Particle Physics
• Astrophysics

Background:

• The 21-cm signal probes the early universe during the cosmic dawn and dark ages.
• Interactions between the standard and dark sectors are key to understanding cosmic evolution.
• Dark photons are hypothetical particles that could mediate interactions between visible and dark matter.

Purpose of the Study:

• To introduce novel signatures in 21-cm measurements.
• To explore the implications of dark sector interactions for early universe observations.
• To provide a new observational window for physics beyond the Standard Model.

Main Methods:

• Analyzing 21-cm brightness temperature fluctuations.
• Modeling resonant dark photon-to-photon conversions.
• Investigating spectral edges and endpoints as unique signatures.

Main Results:

• Identified spectral edges and endpoints as distinct features in 21-cm signals.
• Demonstrated that these features arise from dark photon-photon conversions.
• Showed the potential for these signatures in current and future experiments.

Conclusions:

• These spectral signatures offer a new, qualitatively different approach to searching for physics beyond the Standard Model.
• 21-cm observations provide a powerful tool for probing dark sector physics.
• The findings have direct implications for experiments targeting the cosmic dawn and dark ages.