Holographic Bubbles with Jecco: Expanding, Collapsing and Critical

TL;DR

This paper extends holographic models of cosmological bubbles to include circular bubbles, revealing a critical bubble size and complex late-time profiles, using a new Julia-based simulation code called Jecco.

Contribution

The work introduces a new 3+1 evolution code, Jecco, for simulating holographic bubbles in asymptotically AdS spaces, and explores the properties of circular bubbles in a strongly-coupled gauge theory.

Findings

Identification of a critical bubble size.

Rich self-similar late-time bubble profiles.

Development of the Jecco simulation code.

Abstract

Cosmological phase transitions can proceed via the nucleation of bubbles that subsequently expand and collide. The resulting gravitational wave spectrum depends crucially on the properties of these bubbles. We extend our previous holographic work on planar bubbles to circular bubbles in a strongly-coupled, non-Abelian, four-dimensional gauge theory. This extension brings about two new physical properties. First, the existence of a critical bubble, which we determine. Second, the bubble profile at late times exhibits a richer self-similar structure, which we verify. These results require a new 3+1 evolution code called Jecco that solves the Einstein equations in the characteristic formulation in asymptotically AdS spaces. Jecco is written in the Julia programming language and is freely available. We present an outline of the code and the tests performed to assess its robustness and performance.