Radiative transfer in stars by feebly interacting bosons

Understand

Starting from first principles, we study radiative transfer by new feebly-interacting bosons (FIBs) such as axions, axion-like particles (ALPs), dark photons, and others.

• Our key simplification is to include only boson emission or absorption (including decay), but not scattering between different modes of the radiation field.
• Based on a given distribution of temperature and FIB absorption rate in a star, we derive explicit volume-integral expressions for the boson luminosity, reaching from the free-streaming to the strong-trapping limit.
• The latter is seen explicitly to correspond to quasi-thermal emission from a "FIB sphere" according to the Stefan-Boltzmann law.