Radiative viscosity of neutron stars

Understand

We study non-linear effects of radiative viscosity of $npe$ matter in neutron stars for both direct Urca process and modified Urca process, and find that non-linear effects will decrease the ratio of radiative viscosity to bulk viscosity from 1.5 to 0.5 (for direct Urca process) and 0.375 (for modified Urca process).

• Which means that for small oscillations of neutron star, the large fraction of oscillation energy is emitted as neutrinos; but for large enough ones, bulk viscous dissipation dominates.