On the primordial origin of the smoothing excess in the Planck temperature power spectrum in light of LSS data

Abstract

The Planck DR3 measurements of the temperature and polarization anisotropies power spectra of the cosmic microwave background (CMB) show an excess of smoothing of the acoustic peaks with respect to ΛCDM, often quantified by a phenomenological parameter A L. A specific feature superimposed to the primordial power spectrum has been suggested as a physical solution for this smoothing excess. Here, we investigate the impact of this specific localized oscillation with a frequency linear in the wavenumber, designed to mimic the smoothing of CMB temperature spectrum corresponding to A L ≃ 1.1–1.2 on the matter power spectrum. We verify the goodness of the predictions in perturbation theory at next-to-leading order with a set of N-body simulations, a necessary step to study the non-linear damping of these primordial oscillations. We show that for a large portion of the parameter space, the amplitude of this primordial oscillation can be strongly damped on the observed nonlinear matter power spectrum at z = 0, but a larger signal is still persistent at z ≲ 2 and is therefore a target for future galaxy surveys at high redshifts. From an analysis of the BOSS DR12 two-point correlation function, we find 𝒜lin < 0.26 at 95% CL by keeping the frequency fixed to the best-fit of Planck data.

Euclid: The search for primordial features

“…We have modelled the nonlinear matter power spectrum with time-sliced perturbation theory predictions at leading order (Vasudevan et al 2019;Beutler et al 2019;Ballardini et al 2020;Ballardini & Finelli 2022) calibrated on a set of Nbody simulations from COLA (Tassev et al 2013;Howlett et al 2015) and GADGET (Springel et al 2001;Springel 2005;Ballardini et al 2020;Ballardini & Finelli 2022) for GC sp ; see Sect. 4.2.…”

“…We fix the standard cosmological parameters and the amplitude and phase of the feature, and we study the effect of varying the frequency of the primordial oscillations over the set of values ω X ∈ {0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2}. Following the analysis done by Ballardini & Finelli (2022), we run each simulation with 1024 3 dark matter particles in a comoving box with side length of 1024 h −1 Mpc evolved with 30 time steps. We set at redshift z = 9 the initial conditions that we generate using second-order Lagrangian perturbation theory, with the 2LPTic code (Crocce et al 2006).…”

“…These include the dip in power in the multipole range ∼ 20-40 and an oscillatory pattern at the intermediate scales ∼ 700-800. Models with primordial features have also been studied in the context of the anomalous CMB lensing smoothing excess, as well as the H 0 and S 8 tensions (Planck Collaboration X 2020; Domènech & Kamionkowski 2019;Liu & Huang 2020;Domènech et al 2020;Keeley et al 2020;Hazra et al 2022;Antony et al 2023;Ballardini & Finelli 2022).…”

“…This has been studied extensively with forecast analyses in Wang et al (1999), Zhan et al (2006), Huang et al (2012), Chen et al (2016a,b), Ballardini et al (2016Ballardini et al ( , 2018Ballardini et al ( , 2020, Xu et al (2016), Ansari Fard & Baghram (2018), Palma et al (2018), Ballardini (2019), Beutler et al (2019), Debono et al (2020), Li et al (2022) and demonstrated on real data in Beutler et al (2019), Ballardini et al (2023), and Mergulhão et al (2023) showing that current galaxy clustering data of the Baryon Oscillation Spectroscopic Survey (BOSS) alone can already provide constraints that are competitive with those derived from the Planck CMB data. Given the potential of the Euclid mission, it is imperative to have a good description of the LSS observables on all observed scales, and to do so, nonlinear corrections need to be correctly accounted for (Vlah et al 2016;Vasudevan et al 2019;Beutler et al 2019;Ballardini et al 2020;Chen et al 2020;Li et al 2022;Ballardini & Finelli 2022).…”