Observational assessment of the viability of de Sitter-G\"odel-de Sitter phase transition

TL;DR

This paper investigates the potential observational signatures of a hypothetical early universe phase transition from de Sitter to G"odel and back, using simulations and current Planck data to constrain its effects on cosmic perturbations.

Contribution

It introduces a simulation framework for the de Sitter-G"odel-de Sitter transition and constrains its parameters using Planck data, providing insights into early universe physics.

Findings

No evidence for the dGd transition in current data.

Constraints on transition parameters are consistent with standard inflation.

Future surveys could significantly improve detection sensitivity.

Abstract

de Sitter--G\"odel--de Sitter phase transition(dGd) is a possible geometrical phase transition in the very early universe. It induces fluctuations with possibly observable traces on matter and radiation fields. Here we present a simulation based on dGd to investigate possible perturbations which could be along with the standard inflationary fluctuations in the cosmic microwave background (CMB) and distribution of the large-scale structure. The power spectrum of perturbations is characterized by a parameter pair, labeled here as ($p_1, p_2$). With {\it Planck} observations we find $p_1=0.008^{+0.003}_{-0.008}$ and $p_2= 0.002^{+0.001}_{-0.002}$ consistent with pure inflationary power spectrum and no hint for the dGd transition. Also, it is estimated future large-scale surveys such as Euclid and SKA can further tighten the constraints up to an order of magnitude and probe the physics of the early universe with much higher precision.