Cosmology

Pylians provide a set of routines to carry out simple cosmological calculations.

Comoving distance

The comoving distance to redshift z can be computed as:

import cosmology_library as CL

z       = 1.0
Omega_m = 0.3175
Omega_l = 0.6825

# compute the comoving distance to redshift z in Mpc/h
r = CL.comoving_distance(z, Omega_m, Omega_l)  #Mpc/h

Linear growth factor

The linear growth factor to redshift z can be computed as:

import cosmology_library as CL

z       = 1.0
Omega_m = 0.3175
Omega_l = 0.6825

# compute the linear growth factor
D = CL.linear_growth_factor(z, Omega_m, Omega_l)

Halofit

From a linear power spectrum at z=0, Pylians can find the non-linear matter power spectrum halofit by Takahashi 2012 as

import numpy as np
import cosmology_library as CL

z       = 1.0
Omega_m = 0.3175
Omega_l = 0.6825

# read the linear power spectrum
k_lin, Pk_lin = np.loadtxt('my_Pk_file_z=0.txt', unpack=True)

# find the non-linear power spectrum from halofit
Pk_nl = CL.Halofit_12(Omega_m, Omega_l, z, k_lin, Pk_lin)