Probing inflationary features with galaxy ultraviolet luminosity function observables

TL;DR

This paper uses galaxy ultraviolet luminosity functions at high redshifts to constrain modifications to the inflationary power spectrum, focusing on features like bumps and oscillations, providing direct constraints complementary to reionization measurements.

Contribution

It introduces galaxy UV luminosity functions as a novel, direct probe for inflationary features in the matter power spectrum at high redshifts.

Findings

Galaxy luminosity functions constrain inflationary features at specific wavenumbers.

Upper limits are set on the amplitude of bump-like features.

Constraints are comparable to those from reionization optical depth measurements.

Abstract

We use the galaxy ultraviolet luminosity function measurements at $z=6-9$ to constrain modification to standard inflationary power spectrum. These observables are sensitive to the matter power spectrum which itself depends on inflationary initial conditions. We consider specific models where a bump or oscillatory features are introduced to the standard power law inflation spectrum. We find that the galaxy luminosity observables can probe such modifications at wavenumbers $0.5\lesssim k \lesssim 20$ Mpc$^{-1}$. We obtain upper limits on the amplitude of bump-like features at the mentioned wavenumbers. We obtain constraints which are similar to previous constraints on these models using measurements of optical depth of reionization. However, the galaxy luminosity functions are a more direct probe for these type of models and, therefore, can complement indirect constraints coming from measurements of IGM properties.