Gauge invariant perturbations in teleparallel Horndeski gravity

TL;DR

This paper catalogs cosmological perturbations in the teleparallel Horndeski gravity, aiding the understanding of structure formation and observational analysis in this alternative gravity theory.

Contribution

It provides a comprehensive catalog of perturbations in teleparallel Horndeski gravity, including gauge choices, facilitating comparison with observations.

Findings

Detailed gauge analysis for scalar, vector, tensor perturbations

Framework for incorporating perturbations into observational codes

Comparison with standard Horndeski gravity perturbations

Abstract

We present in the form of a catalogue of the cosmological perturbations within the Bahamonde- Dialektopoulos-Levi Said (BDLS) theory, which serves as the teleparallel counterpart of Horndeski gravity. To understand structure formation in cosmological models, it is essential to study both the background and perturbative aspects of their cosmology. While extensive analysis of both Horndeski gravity and its teleparallel analog exists in the literature, a quantitative understanding requires a detailed examination of their cosmological perturbations. We review here all the different gauges for the scalar, vector and tensor perturbations of a cosmological background up to second order and we hope this will help people who work with observations, to incorporate it in existing codes.