Mass loss and longevity of gravitationally bound oscillating scalar lumps (oscillatons) in D-dimensions

TL;DR

This paper investigates the properties, mass loss, and longevity of spherically symmetric oscillating scalar lumps, called oscillatons, in higher-dimensional spacetimes, focusing on their decay via scalar radiation and their long lifetimes.

Contribution

It introduces a method to compute the extremely small amplitude of outgoing waves in oscillatons, especially in the small-amplitude limit, and applies it to a simple massive scalar field model.

Findings

Oscillatons decay via scalar radiation with extremely long timescales.

A new method is developed to calculate the tiny outgoing wave amplitudes.

Results suggest oscillatons can have lifetimes comparable to the age of the universe.

Abstract

Spherically symmetric oscillatons (also referred to as oscillating soliton stars) i.e. gravitationally bound oscillating scalar lumps are considered in theories containing a massive self-interacting real scalar field coupled to Einstein's gravity in 1+D dimensional spacetimes. Oscillations are known to decay by emitting scalar radiation with a characteristic time scale which is, however, extremely long, it can be comparable even to the lifetime of our universe. In the limit when the central density (or amplitude) of the oscillaton tends to zero (small-amplitude limit) a method is introduced to compute the transcendentally small amplitude of the outgoing waves. The results are illustrated in detail on the simplest case, a single massive free scalar field coupled to gravity.