Primordial gravastar from inflation

TL;DR

This paper proposes that primordial gravastars formed from inflationary bubbles could explain certain gravitational wave signals, with unique echoes in the waveform indicating their presence and evolution.

Contribution

It introduces a novel mechanism for primordial gravastar formation from inflationary bubbles and links it to observable gravitational wave signatures.

Findings

Primordial gravastars can form from inflationary bubbles.

Such gravastars could produce detectable GW echoes.

Potential connection to LIGO/Virgo GW events.

Abstract

The dS bubbles can nucleate spontaneously during inflation, and will be stretched by the cosmological expansion to astrophysical scale. We report on a novel phenomenon that such a bubble might develop into a gravastar (an ultra-compact object with a dS core) after inflation, which witnessed the occurrence of inflation and would survive till today. It is pointed out that if a primordial gravastar was involved in one of the LIGO/Virgo gravitational wave (GW) events, the post-merger object could be a gravastar that will eventually collapse into a black hole. As a result, the late-time GW ringdown waveform will exhibit a series of "echoes" with intervals increasing with time.