Comparing Production Sources in a Stellar Profile

Volumetric emission rate as a function of radius in a representative collapsed pre-supernova at a snapshot in time. Shown are the rates for mu and anti-mu neutrinos via electron-positron annihilation (blue, dashed) and nucleon-nucleon bremsstahlung at arbitrary nucleon degeneracy (black). Also shown is the bremsstrahlung emission in the non-degenerate nucleon limit (red, dot-dashed). Note that at between 20 and 30 kilometers in radius, bremsstrahlung begins to dominate electron-positron annihilation as a production mechanism. This may have important consequences for the emergent mu and tau neutrino spectra since these neutrinos decouple from the dense nuclear matter near this radius.