Axiverse and Black Hole

TL;DR

This paper explores the axiverse concept from string theory, focusing on black hole instabilities caused by axionic fields, and discusses their physical mechanisms and astrophysical implications.

Contribution

It provides an overview of the axiverse idea and analyzes black hole instability as a key phenomenon arising from axionic fields predicted by string theory.

Findings

Black hole superradiance can occur due to axionic fields.

Axionic fields can lead to observable astrophysical phenomena.

The paper discusses potential signals of axion-induced black hole instabilities.

Abstract

String theory/M-theory generally predicts that axionic fields with a broad mass spectrum extending below 10^{-10}eV are produced after compactification to four dimensions. These axions/fields provoke a rich variety of cosmophysical phenomena on different scales depending on their masses and provide us new windows to probe the ultimate theory. In this article, after overviewing this axiverse idea, I take up the black hole instability as the most fascinating one among such axionic phenomena and explain its physical mechanism and astrophysical predictions.