Guillermo F. Abellán

arXiv2022

Improved cosmological constraints on the neutrino mass and lifetime

We present cosmological constraints on the sum of neutrino masses as a function of the neutrino lifetime, in a framework in which neutrinos decay into dark radiation after becoming non-relativistic. We find that in this regime the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO) and (uncalibrated) luminosity distance to supernovae from the Pantheon catalog constrain the sum of neutrino masses $\sum m_ν$ to obey $\sum m_ν< 0.42$ eV at (95$\%$ C.L.). While the the bound has improved significantly as compared to the limits on the same scenario from Planck 2015, it still represents a significant relaxation of the constraints as compared to the stable neutrino case. We show that most of the improvement can be traced to the more precise measurements of low-$\ell$ polarization data in Planck 2018, which leads to tighter constraints on $τ_{\rm reio}$ (and thereby on $A_s$), breaking the degeneracy arising from the effect of (large) neutrino masses on the amplitude of the CMB power spectrum.

hep-ph↗

arXiv2021

Early dark energy resolution to the Hubble tension in light of weak lensing surveys and lensing anomalies

Early Dark Energy (EDE) contributing a fraction $f_{\rm EDE}(z_c)\sim 10 \%$ of the energy density of the universe around $z_c\simeq 3500$ and diluting as or faster than radiation afterwards, can provide a resolution to the Hubble tension, the $\sim 5σ$ discrepancy between the $H_0$ value derived from early- and late-universe observations within $Λ$CDM. However, it has been pointed out that Large-Scale Structure (LSS) data, which are in $\sim3σ$ tension with $Λ$CDM and EDE cosmologies, might alter these conclusions. We reassess the viability of the EDE against a host of high- and low-redshift measurements, by combining LSS observations from recent weak lensing (WL) surveys with CMB, Baryon Acoustic Oscillation (BAO), growth function (FS) and Supernova Ia (SNIa) data. Introducing a model whose only parameter is $f_{\rm EDE}(z_c)$, we report a $\sim 2σ$ preference for non-zero $f_{\rm EDE}(z_c)$ from Planck data alone and the tension with SH0ES is reduced below $2σ$. Adding BAO, FS and SNIa does not affect this result, while the inclusion of a prior on $H_0$ from SH0ES increase the preference for non-zero EDE to $\sim3.6σ$. After checking the EDE non-linear matter power spectrum predicted by standard semi-analytical algorithms via a set of $N$-body simulations, we show that current WL data do not rule out EDE. We also caution against the interpretation of constraints obtained from combining statistically inconsistent data sets within the $Λ$CDM cosmology. In light of the CMB lensing anomalies, we show that the lensing-marginalized CMB data also favor non-zero $f_{\rm EDE}(z_c)$ at $\sim2σ$, predicts $H_0$ in $1.4σ$ agreement with SH0ES and $S_8$ in $1.5σ$ ($0.8σ$) agreement with KV (DES) data. Alternatively, we discuss promising extensions of the EDE cosmology that could allow to fully restore cosmological concordance.

astro-ph.CO↗