Cooling Times

Class providing models of the cooling time (in Gyr) for gas in the hot halo surrounding a galaxy, defined as the ratio of the thermal energy density to the radiative cooling rate. Given temperature, density, elemental abundances, chemical species densities, and an ambient radiation field, implementations typically evaluate \(t_\mathrm{cool} = (3/2) n k_\mathrm{B} T / \mathcal{L}\). The logarithmic gradients with respect to density and temperature are also provided for use in implicit ODE solvers that integrate the cooling flow equations.

Default implementation: coolingTimeSimple

Methods

time → double precision

Returns the cooling time for gas in the hot atmosphere surrounding the galaxy in units of Gyr.

  • type (treeNode ), intent(inout) :: node

  • double precision , intent(in ) :: temperature , density

  • type (abundances ), intent(in ) :: gasAbundances

  • type (chemicalAbundances ), intent(in ) :: chemicalDensities

  • class (radiationFieldClass), intent(inout) :: radiation

gradientDensityLogarithmic → double precision

Returns the logarithmic derivative of cooling time with respect to density for gas in the hot atmosphere surrounding the galaxy.

  • type (treeNode ), intent(inout) :: node

  • double precision , intent(in ) :: temperature , density

  • type (abundances ), intent(in ) :: gasAbundances

  • type (chemicalAbundances ), intent(in ) :: chemicalDensities

  • class (radiationFieldClass), intent(inout) :: radiation

gradientTemperatureLogarithmic → double precision

Returns the logarithmic derivative of cooling time with respect to temperature for gas in the hot atmosphere surrounding the galaxy.

  • type (treeNode ), intent(inout) :: node

  • double precision , intent(in ) :: temperature , density

  • type (abundances ), intent(in ) :: gasAbundances

  • type (chemicalAbundances ), intent(in ) :: chemicalDensities

  • class (radiationFieldClass), intent(inout) :: radiation

coolingTimeSimple

A cooling time class in which the cooling time is simply

\[t_\mathrm{cool} = {N \over 2} {\mathrm{k}_\mathrm{B} T n_\mathrm{tot} \over \Lambda},\]

where \(N=\)[degreesOfFreedom] is the number of degrees of freedom in the cooling gas which has temperature \(T\) and total particle number density (including electrons) \(n_\mathrm{tot}\) and \(\Lambda\) is the cooling function.

(Default implementation)

Methods

  • calculationReset — Reset memoized calculations.

Parameters

  • [degreesOfFreedom] (real; default 3.0d0) — Number of degrees of freedom to assume when computing the energy density of cooling gas in the “simple” cooling time class.