Neutrino Losses

We model thermal neutrino losses (plasma, photo-, pair-, recombination, and Bremsstrahlung) using the method described in [40]. This neutrino loss term is included in all of the reaction networks by default, and modifies the energy equation to have the form (for Strang splitting):

\[\frac{de}{dt} = \epsilon - \epsilon_\nu\]

where \(\epsilon_\nu\) are the thermal neutrino losses.

Note

Thermal neutrino losses can be disabled at compile time by setting the make variable USE_NEUTRINOS = FALSE.

The interface for the neutrino loss function is:

template <int do_derivatives>
AMREX_GPU_HOST_DEVICE AMREX_INLINE
void sneut5(const amrex::Real temp, const amrex::Real den,
            const amrex::Real abar, const amrex::Real zbar,
            amrex::Real& snu, amrex::Real& dsnudt, amrex::Real& dsnudd,
            amrex::Real& dsnuda, amrex::Real& dsnudz)

Here, the template parameter, do_derivatives, can be used to disable the code the computes the derivatives of the neutrino loss, for example, if a numerical Jacobian is used. The output is

  • snu : \(\epsilon_\nu\), the neutrino loss in erg/g/s

  • dsnudt : \(d\epsilon_\nu/dT\)

  • dsnudd : \(d\epsilon_\nu/d\rho\)

  • dsnuda : \(d\epsilon_\nu/d\bar{A}\)

  • dsnudz : \(d\epsilon_\nu/d\bar{Z}\)

By default, we do not include the recombination terms when calculating the total losses since its effect is negligible. This is controlled by the include_recomb parameter defined in Microphysics/neutrinos/_parameters. To include the recombination terms, set neutrino_cooling.include_recomb = 1 in the inputs file.