CosmoCoffee

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import numpy as np
import matplotlib.pyplot as plt
import camb
from camb import model, initialpower

# Set up the cosmological parameters
pars = camb.CAMBparams()
pars.set_cosmology(H0=67.5, ombh2=0.022, omch2=0.122)
pars.InitPower.set_params(ns=0.965)
pars.set_for_lmax(2500, lens_potential_accuracy=1)

# Obtain results from CAMB
results = camb.get_results(pars)

# Redshift range
z = np.logspace(-2, 3, 300)

# Galaxy lensing kernel
z0 = 1.0
sigma_z = 1.0
dNdz = np.exp(-(z - z0)**2 / (2 * sigma_z**2))
chi = results.comoving_radial_distance(z)
chi_star = results.comoving_radial_distance(1100)
W_gal = chi * (1 - chi / chi_star) * dNdz

# CMB lensing kernel
W_cmb = 1.5 * pars.omegam * (1 + z) * chi * (chi_star - chi) / chi_star**2

plt.figure(figsize=(10, 5))
plt.plot(z, W_gal/W_gal.max(), label='Galaxy lensing', color='orange')
plt.plot(z, W_cmb/W_cmb.max(), label='CMB lensing', color='blue')
plt.axvline(z[np.argmax(W_gal)], color='black', linestyle='--', linewidth=0.7)
plt.xscale('log')
plt.xlim(z.min(), z.max())
plt.ylim(0, 1.1)
plt.xlabel('Redshift z')
plt.ylabel('Weight $W(z)/W_{max}$')
plt.legend()
plt.grid(True, which='both', linestyle='--', linewidth=0.5)
plt.tight_layout()
plt.show()