Large Scale Structure Forecast Constraints on Particle Production During Inflation

TL;DR

Bursts of particle production during inflation can imprint localized bumps in the primordial power spectrum, which propagate to the CMB and large-scale structure. The authors forecast constraints on the feature amplitude $A_{\text{IR}}$ and its position $k_{\text{IR}}$ using Fisher information from Planck, CIP, SKA, and galaxy/cluster surveys, modeling the feature with $\mathcal P(k)=\Delta_{\mathcal R}^2 (k/k_{\text{pivot}})^{n_s-1} + A_{\text{IR}} (\pi e/3)^{3/2} (k/k_{\text{IR}})^3 \exp[-(\pi/2)(k/k_{\text{IR}})^2]$. Planck alone can constrain $A_{\text{IR}}$ to about $0.5\%$, SKA to about $0.1\%$, and CIP can extend sensitivity up to $k_{\text{IR}}\lesssim 1\,h\,\mathrm{Mpc}^{-1}$, with combinations such as Planck+Planck+CIP and Planck+SKA yielding the strongest constraints. The study demonstrates substantial gains in testing inflationary physics on small scales, while noting potential further improvements from including non-Gaussianity and more sophisticated modeling.

Abstract

Bursts of particle production during inflation provide a well-motivated mechanism for creating bump like features in the primordial power spectrum. Current data constrains these features to be less than about 5% the size of the featureless primordial power spectrum at wavenumbers of about 0.1 h Mpc^{-1}. We forecast that the Planck cosmic microwave background experiment will be able to strengthen this constraint to the 0.5% level. We also predict that adding data from a square kilometer array (SKA) galaxy redshift survey would improve the constraint to about the 0.1% level. For features at larger wave-numbers, Planck will be limited by Silk damping and foregrounds. While, SKA will be limited by non-linear effects. We forecast for a Cosmic Inflation Probe (CIP) galaxy redshift survey, similar constraints can be achieved up to about a wavenumber of 1 h Mpc^{-1}.

Figures (7)

• Figure 1: The primordial power spectrum plus particle creation features with $A_{\hbox{\scriptsize{\tiny IR}}}$ = 1.25 $\times 10^{-10}$ at position $k_{\hbox{\scriptsize{\tiny IR}}}= 0.1 \,h\,{\rm Mpc}^{-1}$ (red dashed).
• Figure 2: The matter power spectrum from a featureless primordial power spectrum (blue solid) and the matter power spectrum from a primordial power spectrum which has a particle creation feature with amplitude $A_{\hbox{\scriptsize{\tiny IR}}}$ = 1.25 $\times 10^{-10}$ at position $k_{\hbox{\scriptsize{\tiny IR}}} = 0.1 \,h\,{\rm Mpc}^{-1}$ (red dashed).
• Figure 3: The CMB angular power spectrum from a featureless primordial power spectrum (blue solid) and the CMB angular power spectrum from a primordial power spectrum with a particle creation feature which has $A_{\hbox{\scriptsize{\tiny IR}}}$ = 1.25 $\times 10^{-10}$ at position $k_{\hbox{\scriptsize{\tiny IR}}}= 0.1 \,h\,{\rm Mpc}^{-1}$ (red dashed).
• Figure 4: Marginalised probability contours containing 68% of the posterior probability between $\alpha_{{s}}$ and $A_{\hbox{\scriptsize{\tiny IR}}} = 1.25 \times 10^{-10}$.
• Figure 5: 1-$\sigma$ marginalised constraints on the amplitude and position of particle production feature for Planck, Planck + SKA and Planck + CIP. The uncertainty in $k_{\hbox{\scriptsize{\tiny IR}}}$ is multiplied by 5 to make them more visible.