CosmoFit.TauLikelihood

class CosmoFit.TauLikelihood(cosmology, version='planck2018_lowe')

Bases: GaussianPriorLikelihood

The Planck 2018 large-scale-polarization constraint on the reionization optical depth.

Versions: "planck2018_lowe" (default), tau = 0.0506 +- 0.0086 from the low-l EE likelihood alone; and "planck2018", the familiar 0.0544 +- 0.0073, which is the TT,TE,EE+lowE posterior and so already contains the high-l spectra. Next to "planck_lite" only the first is right – the second counts plik’s spectra twice, and Fitter warns. The second is the shorthand to use where no CMB spectra are in the fit.

Only meaningful alongside PlanckLiteLikelihood, which covers l >= 30 only. There, tau enters solely through the exp(-2 tau) damping of the spectra and is therefore degenerate with the primordial amplitude A_s; this prior is what breaks that degeneracy, and it is the standard companion to a high-l-only CMB fit rather than an optional extra. Without it, sigma8 and anything derived from it are unconstrained.

Parameters:

version (str)

__init__(cosmology, version='planck2018_lowe')

Parameters:

version (str)

Methods

__init__(cosmology[, version])
chi2()	Chi-square statistic.
log_likelihood()	Return log-likelihood.
model()	Predicted value of the constrained quantity.
predictions()	Alias for model().
residuals()	Data minus model residual (a length-1 vector).
summary()	Return a summary of the likelihood evaluation.

Attributes

n_data	Number of data points.
name_and_size	Name together with the number of data points.
observable
version	The version actually loaded -- the registry's first one when none was asked for, which is what load_gaussian_prior resolves None to.