%0 Journal Article
%T Is the Harrison-Zel'dovich spectrum coming back? ACT preference for n(s) similar to 1 and its discordance with Planck
%A Giare, W.
%A Renzi, F.
%A Mena, O.
%A Di Valentino, E.
%A Melchiorri, A.
%J Monthly Notices of the Royal Astronomical Society
%D 2023
%V 521
%N 2
%I Oxford Univ Press
%@ 0035-8711
%G English
%F Giare_etal2023
%O WOS:000957248500013
%O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=5510), last updated on Sat, 29 Apr 2023 17:02:52 +0000
%X The Data Release 4 of the Atacama Cosmology Telescope (ACT) shows an agreement with an Harrison-Zel'dovich primordial spectrum (n(s) = 1.009 +/- 0.015), introducing a tension with a significance of 99.3 per cent Confidence Level (CL) with the results from the Planck satellite. The discrepancy on the value of the scalar spectral index is neither alleviated with the addition of large scale structure information nor with the low multipole polarization data. We discuss possible avenues to alleviate the tension relying on either neglecting polarization measurements from ACT or in extending different sectors of the theory.
%K cosmological parameters
%K inflation
%K cosmology: observations
%K cosmology: theory
%R 10.1093/mnras/stad724
%U https://arxiv.org/abs/2210.09018
%U https://doi.org/10.1093/mnras/stad724
%P 2911-2918