Local measurement of H₀

Synopsis:

Prototype class for local Hubble parameter measurements

Author:

Jesus Torrado, Pablo Lemos

This is a simple gaussian likelihood for the latest local \(H_0\) measurements using a combination of different data.

The above are all based on simple Gaussian posteriors for the value of H0 today, which is not what is directly measured. It can be more accurate to put a constraint on the intrinsic magnitude, which can then be combined with Supernovae constraints to relate to the expansion. An example is provided in

• H0.riess2020Mb: Riess et al. 2020 constraint on M_b (arXiv:2012.08534)

which should be run in combination with sn.pantheon with use_abs_mag: True (contributed by Pablo Lemos).

Using a different measurement

If you would like to use different values for the \(H_0\) constraint, as a mean and a standard deviation, simply add the following likelihood, substituting mu_H0 and sigma_H0 for the respective values:

likelihood:
  my_H0:
    external: 'lambda _self: -0.5 * (_self.provider.get_param("H0") - mu_H0)**2 / (sigma_H0)**2'
    requires: ["H0"]

Available internal likelihoods

H0.freedman2020:
  Local $H_0$ measurement from \cite{Freedman:2020dne}.

H0.riess2018a:
  Local $H_0$ measurement from \cite{Riess:2018uxu}.

H0.riess2018b:
  Local $H_0$ measurement from \cite{Riess:2018byc}.

H0.riess201903:
  Local $H_0$ measurement from \cite{Riess:2019cxk}.

H0.riess2020:
  Local $H_0$ measurement from  \cite{Riess:2020fzl}.

H0.riess2020Mb:
  Local $H_0$ measurement from  \cite{Riess:2020fzl}, in terms of magnitude measurement.

Use cobaya-doc and cobaya-bib to see details for a given likelihood.