skypy.power_spectrum.growth_function_derivative¶

skypy.power_spectrum.growth_function_derivative(redshift, cosmology, gamma=0.5454545454545454)[source] [edit on github]¶

First derivative of the growth function.

Function used to calculate D’(z), derivative of the growth function with respect to redshift as in [1] equation 16.

Parameters:

redshift(nz,) array_like: Array of redshifts at which to evaluate the growth function.
cosmologyastropy.cosmology.Cosmology: Cosmology object providing methods for the evolution history of omega_matter and omega_lambda with redshift.
gammafloat: Growth index providing an efficient parametrization of the matter perturbations.

Returns:

growth_function_derivative(nz,) array_like: The redshift scaling of the derivative of the growth function.

Notes

The first derivative of the growth function, \(D(z)\), with respect to redshift reads

\[D'(z) = - \frac{D(z) f(z)}{1 + z} \;.\]

With \(f(z)\) the growth factor.

References

[1]