English

Hubble tension or a transition of the Cepheid SnIa calibrator parameters?

Cosmology and Nongalactic Astrophysics 2021-12-15 v2 General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory

Abstract

We re-analyze the Cepheid data used to infer the value of H0H_0 by calibrating SnIa. We do not enforce a universal value of the empirical Cepheid calibration parameters RWR_W (Cepheid Wesenheit color-luminosity parameter) and MHWM_H^{W} (Cepheid Wesenheit H-band absolute magnitude). Instead, we allow for variation of either of these parameters for each individual galaxy. We also consider the case where these parameters have two universal values: one for low galactic distances D<DcD<D_c and one for high galactic distances D>DcD>D_c where DcD_c is a critical transition distance. We find hints for a 3σ3\sigma level mismatch between the low and high galactic distance parameter values. We then use AIC and BIC criteria to compare and rank the following types of models: Base models: Universal values for RWR_W and MHWM_H^{W} (no parameter variation), I Individual fitted galactic RWR_W with a universal fitted MHWM_H^{W}, II Universal fixed RWR_W with individual fitted galactic MHWM_H^{W}, III Universal fitted RWR_W with individual fitted galactic MHWM_H^{W}, IV Two universal fitted RWR_W (near and far) with one universal fitted MHWM_H^{W}, V Universal fitted RWR_W with two universal fitted MHWM_H^{W} (near and far), VI Two universal fitted RWR_W with two universal fitted MHWM_H^{W} (near and far). We find that the AIC and BIC criteria consistently favor model IV instead of the commonly used Base model where no variation is allowed for the Cepheid empirical parameters. The best fit value of the SnIa absolute magnitude MBM_B and of H0H_0 implied by the favored model IV is consistent with the inverse distance ladder calibration based on the CMB sound horizon H0=67.4±0.5kms1Mpc1H_0=67.4\pm 0.5\,km\,s^{-1}\,Mpc^{-1}. Thus in the context of the favored model IV the Hubble crisis is not present. This model may imply the presence of a fundamental physics transition taking place at a time more recent than 100Myrs100\,Myrs ago.

Keywords

Cite

@article{arxiv.2109.04406,
  title  = {Hubble tension or a transition of the Cepheid SnIa calibrator parameters?},
  author = {Leandros Perivolaropoulos and Foteini Skara},
  journal= {arXiv preprint arXiv:2109.04406},
  year   = {2021}
}

Comments

35 pages, 17 Figures, 7 Tables. Included comments based on discussion with SH0ES team. 2 Figures added. Included discussion on theoretical models based on false vacuum decay. The numerical analysis files and the data that lead to the production of the figures are publicly available at https://github.com/FOTEINISKARA/Cepheid_SnIa_Calibrator_Data_Transition