Structure Formation and Backreaction in Growing Neutrino Quintessence

TL;DR

This paper investigates how neutrino mass variations linked to dark energy influence cosmic structure formation, employing relativistic N-body simulations to explore large-scale neutrino structures and their effects on universe evolution.

Contribution

It introduces a comprehensive relativistic N-body simulation approach to study growing neutrino quintessence, including local dark energy variations and backreaction effects.

Findings

Large-scale neutrino structures form and impact matter and dark energy evolution.

Relativistic velocities and local field variations significantly influence structure formation.

Simulation successfully models phenomena until redshift z ~ 1.

Abstract

A dependence of the neutrino masses on the dark energy scalar field could provide a solution to the why now problem of dark energy. The dynamics of the resulting cosmological model, growing neutrino quintessence, include an attractive force between neutrinos substantially stronger than gravity. We present a comprehensive approach towards an understanding of the full cosmological evolution including the formation of large-scale neutrino structures. Important effects we account for are local variations in the dark energy and the backreaction on the background evolution, as well as relativistic neutrino velocities. For this aim, we develop a relativistic N-body treatment of the neutrinos combined with an explicit computation of the local quintessence field. At its current stage, the simulation method is successful until z ~ 1 and reveals a rich phenomenology. We obtain a detailed picture of the formation of large-scale neutrino structures and their influence on the evolution of matter, dark energy, and the late-time expansion of the universe.