On the Hubble Constant Tension in the SNe Ia Pantheon Sample
Abstract
The Hubble constant (H_{0}) tension between Type Ia supernovae (SNe Ia) and Planck measurements ranges from 4 to 6σ. To investigate this tension, we estimate H_{0} in the ΛCDM and ${w}_{0}{w}_{a}$ CDM (cold dark matter) models by dividing the Pantheon sample, the largest compilation of SNe Ia, into 3, 4, 20, and 40 bins. We fit the extracted H_{0} values with a function mimicking the redshift evolution: $g{(z)={H}_{0}(z)={\tilde{H}}_{0}/(1+z)}^{\alpha }$ , where α indicates an evolutionary parameter and ${\tilde{H}}_{0}={H}_{0}$ at z = 0. We set the absolute magnitude of SNe Ia so that ${H}_{0}\,=73.5\,\mathrm{km}\,{{\rm{s}}}^{1}\,{\mathrm{Mpc}}^{1}$ , and we fix fiducial values for ${{\rm{\Omega }}}_{0m}^{{\rm{\Lambda }}\mathrm{CDM}}=0.298$ and ${{\rm{\Omega }}}_{0m}^{{w}_{0}{w}_{a}\mathrm{CDM}}=0.308$ . We find that H_{0} evolves with redshift, showing a slowly decreasing trend, with α coefficients consistent with zero only from 1.2 to 2.0σ. Although the α coefficients are compatible with zero in 3σ, this however may affect cosmological results. We measure locally a variation of ${H}_{0}(z=0){H}_{0}(z=1)=0.4\,\mathrm{km}\,{{\rm{s}}}^{1}\,{\mathrm{Mpc}}^{1}$ in three and four bins. Extrapolating ${H}_{0}(z)$ to z = 1100, the redshift of the last scattering surface, we obtain values of H_{0} compatible in 1σ with Planck measurements independent of the cosmological models and number of bins we investigated. Thus, we have reduced the H_{0} tension in the range from 54% to 72% for both cosmological models. If the decreasing trend of ${H}_{0}(z)$ is real, it could be due to astrophysical selection effects or to modified gravity.
 Publication:

The Astrophysical Journal
 Pub Date:
 May 2021
 DOI:
 10.3847/15384357/abeb73
 arXiv:
 arXiv:2103.02117
 Bibcode:
 2021ApJ...912..150D
 Keywords:

 Type Ia supernovae;
 1728;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 20 pages, 6 figures, 1 table