# The tension between global and local determinations of the Hubble constant in the presence of a non-standard dark energy.

Name: David Francisco Camarena Torres

Type: MSc dissertation

Publication date: 26/02/2018

Advisor:

Name | Role |
---|---|

Valerio Marra | Advisor * |

Examining board:

Name | Role |
---|---|

Wiliam Santiago Hipolito Ricaldi | External Examiner * |

Valerio Marra | Advisor * |

Oliver Fabio Piattella | Internal Examiner * |

Miguel Boavista Quartin | External Examiner * |

Summary: There is a 3.4σ tension between local and global measurements of the Hubble constant H0 provided by observations of SNe Ia [1] and CMB [2], respectively. This tension cannot be totally explained by the concordance ΛCDM model and could be produced by unknown

systematics on the calibration of the cosmic distance ladder or CMB analysis. However, in the absence of these systematics, the tension could be a hint for physics beyond the ΛCDM model. On the other hand, it is well known that the linear perturbation theory predicts a cosmic variance on the Hubble parameter H0, produced by peculiar velocities

and local structures, which leads to systematic errors on local determinations of H0. Here, we consider this cosmic variance, predicted by linear perturbation theory, in a presence of a non-standard dark energy, in order to compute the systematic error on the local Hubble

rate. Non-standard dark energy models are represented by the coupled quintessence models and the γCDM, γwCDM and γaCDM parametrizations. Then, we include this systematic error in the Bayesian statistical analysis that uses CMB, BAO, SNe Ia, RSD and H0locl data. Thus, we show the effect of the cosmic variance on the cosmological constraints and the tension problem. Finally, we accomplish the model selection using the AIC and BIC criteria and also show how the systematic error provided for the models of non-standard dark energy could help to alleviate the current tension in determinations of H0.