Relic neutrino decay solution to the excess radio background

Bhupal Dev, P.S.; Di Bari, Pasquale; Martínez-Soler, Ivan; Roshan, Rishav

Abstract

The excess radio background detected by ARCADE 2 represents a puzzle within the standard cosmological model. There is no clear viable astrophysical solution, and therefore, it might indicate the presence of new physics. Radiative decays of a relic neutrino ν_i (either i=1, or i=2, or i=3) into a sterile neutrino ν_ s, assumed to be quasi-degenerate, provide a solution that currently evades all constraints posed by different cosmological observations and reproduces very well the ARCADE 2 data. We find a very good fit to the ARCADE 2 data with best fit values τ_i = 1.46 × 10^21 s and Δ m_i = 4.0 × 10^-5 eV, where τ_i is the lifetime and Δ m_i is the mass difference between the decaying active neutrino and the sterile neutrino. On the other hand, if relic neutrino decays do not explain ARCADE 2 data, then these place a stringent constraint Δ m_i^3/2τ_i ≳ 2 × 10^14 eV^3/2 s in the range 1.4 × 10^-5 eV<Δ m_i < 2.5 × 10^-4 eV. The solution also predicts a stronger 21 cm absorption global signal than the predicted one from the ΛCDM model, with a contrast brightness temperature T_21 = -238^+21_-20 mK (99% C.L.) at redshift z≃ 17. This is in mild tension with the even stronger signal found by the EDGES collaboration, T_21 = - 500^+200_-500 mK, suggesting that this might have been overestimated, possibly receiving a contribution from some unidentified foreground source.

Citation

Bhupal Dev, P., Di Bari, P., Martínez-Soler, I., & Roshan, R. (2024). Relic neutrino decay solution to the excess radio background. Journal of Cosmology and Astroparticle Physics, 2024(04), Article 046. https://doi.org/10.1088/1475-7516/2024/04/046

• Journal Article Type: Article
• Acceptance Date: Feb 26, 2024
• Online Publication Date: Apr 16, 2024
• Publication Date: 2024-04
• Deposit Date: May 15, 2024
• Publicly Available Date: May 15, 2024
• Journal: Journal of Cosmology and Astroparticle Physics
• Electronic ISSN: 1475-7516
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 2024
• Issue: 04
• Article Number: 046
• DOI: https://doi.org/10.1088/1475-7516/2024/04/046
• Keywords: cosmological neutrinos, CMBR theory, neutrino properties
• Public URL: https://durham-repository.worktribe.com/output/2389857