CMB tensions with low-redshift $H_0$ and $S_8$ measurements: impact of a redshift-dependent type-Ia supernovae intrinsic luminosity. (arXiv:1906.09189v1 [astro-ph.CO])

CMB tensions with low-redshift $H_0$ and $S_8$ measurements: impact of a redshift-dependent type-Ia supernovae intrinsic luminosity. (arXiv:1906.09189v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Martinelli_M/0/1/0/all/0/1">Matteo Martinelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tutusaus_I/0/1/0/all/0/1">Isaac Tutusaus</a>

Given the recent increase in precision of our cosmological datasets,
significant tensions between high- and low-redshift observations started to
appear in the measurements of $Lambda$CDM model parameters. In this work we
tackle the tension on the value of the Hubble parameter, $H_0$, and the
weighted amplitude of matter fluctuations, $S_8$, obtained from local or
low-redshift measurements and from cosmic microwave background (CMB)
observations. We combine the main approaches previously used in the literature
by extending the cosmological model and accounting for extra systematic
uncertainties. In more detail, we reconstruct the Dark Energy equation of state
as a function of redshift, while we study the impact of type-Ia supernovae
(SNIa) redshift-dependent astrophysical systematic effects on these tensions.
We consider a SNIa intrinsic luminosity dependence on redshift due to the star
formation rate in its environment, or the metallicity of the progenitor. We
find that the $H_0$ and $S_8$ tensions can be significantly alleviated, or even
removed, if we account for varying Dark Energy for SNIa and CMB data. However,
the tensions remain when we add baryon acoustic oscillations data into the
analysis, even after the addition of extra SNIa systematic uncertainties. This
points towards the need of either new physics beyond late-time Dark Energy, or
other unaccounted systematic effects (particulary in BAO measurements), to
fully solve the present tensions.

Given the recent increase in precision of our cosmological datasets,
significant tensions between high- and low-redshift observations started to
appear in the measurements of $Lambda$CDM model parameters. In this work we
tackle the tension on the value of the Hubble parameter, $H_0$, and the
weighted amplitude of matter fluctuations, $S_8$, obtained from local or
low-redshift measurements and from cosmic microwave background (CMB)
observations. We combine the main approaches previously used in the literature
by extending the cosmological model and accounting for extra systematic
uncertainties. In more detail, we reconstruct the Dark Energy equation of state
as a function of redshift, while we study the impact of type-Ia supernovae
(SNIa) redshift-dependent astrophysical systematic effects on these tensions.
We consider a SNIa intrinsic luminosity dependence on redshift due to the star
formation rate in its environment, or the metallicity of the progenitor. We
find that the $H_0$ and $S_8$ tensions can be significantly alleviated, or even
removed, if we account for varying Dark Energy for SNIa and CMB data. However,
the tensions remain when we add baryon acoustic oscillations data into the
analysis, even after the addition of extra SNIa systematic uncertainties. This
points towards the need of either new physics beyond late-time Dark Energy, or
other unaccounted systematic effects (particulary in BAO measurements), to
fully solve the present tensions.

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