pyBBN v0.9.0: particles/RadiationParticle.py

#

Ultra-relativistic simplifications of density, energy density and pressure calculations

import numpy


__path__ = "../.."


name = 'radiation'

#

Density

$\begin{equation} n = \frac{g}{\pi^2} (aT)^3 \zeta(3) \end{equation}$

def density(particle):

    from particles import STATISTICS

    density = particle.T**3 * particle.dof / numpy.pi**2 * 1.2
    if particle.statistics == STATISTICS.FERMION:

#

Multiplied by $\frac34$ for fermions

        density *= 3./4.

#

    return density

#

Energy density

$\begin{equation} \rho = \frac{\pi^2}{30} g T^4 \end{equation}$

def energy_density(particle):

    from particles import STATISTICS

    density = particle.dof * numpy.pi**2 / 30. * particle.T**4
    if particle.statistics == STATISTICS.FERMION:

#

Multiplied by $\frac78$ for fermions

        density *= 7./8.

#

    return density

#

Pressure

$\begin{equation} P = \frac{\rho}{3} \end{equation}$

def pressure(particle):

    return 1. * energy_density(particle) / 3.

#

Master equation terms

#

$\begin{equation}0\end{equation}$

def numerator(particle):

    return 0.

#

$\begin{equation} \frac{2 \pi^2}{15} g (a T)^3 \end{equation}$

def denominator(particle):

    return 2. * numpy.pi**2 / 15. * particle.dof * (particle.aT)**3