CMB Emulator

We also build an emulator for the CMB power spectra (TT, TE and EE), up to \(\ell=2500\). The priors of the cosmological parameters are roughly centred on the recent Planck 2018 results and are as follows:

\(\boldsymbol{\theta}\)	Distribution	Minimum	Scale	Fiducial
\(\sigma_8\)	Uniform	0.7	0.2	0.8
\(\Omega_{\text{cdm}}\)	Uniform	0.20	0.15	0.2
\(\Omega_b\)	Uniform	0.04	0.02	0.04
\(h\)	Uniform	0.62	0.12	0.7
\(n_s\)	Uniform	0.90	0.2	1.0

A minimal example of how we can use the CMB emulator is as follows:

from jax_cosmo.emulator import EMUCMBdata, prediction_cmb_cls
from cmbrun.cmbcls import get_config

cfg = get_config('planck')
emudata = EMUCMBdata(cfg)
cosmology = np.array([0.8120, 0.265, 0.04938, 0.6732, 0.96605])

# using the emulator to predict the power spectra
mean_tt_jax = prediction_cmb_cls(cosmology, emudata, 'tt')
mean_te_jax = prediction_cmb_cls(cosmology, emudata, 'te')
mean_ee_jax = prediction_cmb_cls(cosmology, emudata, 'ee')