English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

An intriguing discrepancy emerging in the concordance model of cosmology isthe tension between the locally measured value of the Hubble rate, and the'global' value inferred from the cosmic microwave background (CMB). This couldbe due to systematic uncertainties when measuring $H_0$ locally, or it could bethat we live in a highly unlikely Hubble bubble, or other exotic scenarios. Wepoint out that the global $H_0$ can be found by extrapolating $H(z)$ datapoints at high-$z$ down to $z=0$. By doing this in a Bayesian non-parametricway we can find a model-independent value for $H_0$. We apply this to 19measurements based on differential age of passively evolving galaxies as cosmicchronometers. Using Gaussian processes, we find $H_0=64.9 \pm 4.2$ km s$^{-1}$Mpc$^{-1}$ $(1\sigma)$, in agreement with the CMB value, but reinforcing thetension with the local value. An analysis of possible sources of systematicerrors shows that the stellar population synthesis model adopted may change theresults significantly, being the main concern for subsequent studies. Forecastsfor future data show that distant $H(z)$ measurements can be a robust method todetermine $H_0$, where a focus in precision and a careful assessment ofsystematic errors are required.

Evidence for a Lower Value for $H_0$ from Cosmic Chronometers Data?