Cosmology based on f(R) gravity admits 1 eV sterile neutrinos

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• Neutrino oscillation experiments suggest the existence of sterile neutrinos with eV-scale masses.
• Cosmological data, particularly from density fluctuations, impose strong upper limits on total neutrino mass due to free-streaming effects.
• A tension exists between these two sets of observations regarding neutrino mass.

Purpose of the Study:

• To resolve the apparent conflict between neutrino oscillation data and cosmological constraints on neutrino mass.
• To investigate if modified gravity theories can accommodate eV-scale sterile neutrinos within a cosmological context.

Main Methods:

• Utilized theoretical models based on f(R) gravity.
• Analyzed the implications of these models for the accelerated expansion of the Universe.
• Examined how f(R) gravity affects the suppression of density fluctuations and neutrino free-streaming.

Main Results:

• f(R) gravity models provide a framework to reconcile eV-scale sterile neutrinos with cosmological data.
• These models can alleviate the tension by modifying the universe's expansion history and its impact on structure formation.
• The free-streaming suppression of density fluctuations is re-evaluated within the context of modified gravity.

Conclusions:

• The apparent discrepancy concerning sterile neutrino masses is resolved within specific f(R) gravity scenarios.
• Modified gravity offers a potential solution to the tension between particle physics and cosmological observations of neutrino mass.