The gravitational redshift of boson stars

TL;DR

This paper explores the gravitational redshift of boson stars with self-interaction, identifying a maximum redshift value and assessing the observational prospects across various wavebands, highlighting X-ray spectroscopy as a promising method.

Contribution

It provides the first detailed analysis of the maximum gravitational redshift for stable boson stars with self-interaction and evaluates observational strategies.

Findings

Maximum redshift $z_{lim} \,\simeq 0.687$ for stable boson stars.

Direct observation of boson stars is extremely challenging.

X-ray spectroscopy offers the most promising observational approach.

Abstract

We investigate the possible gravitational redshift values for boson stars with a self-interaction, studying a wide range of possible masses. We find a limiting value of $z_{lim} \simeq 0.687$ for stable boson star configurations. We compare theoretical expectation with the observational capabilities in several different wavebands, concluding that direct observation of boson stars by this means will be extremely challenging. X-ray spectroscopy is perhaps the most interesting possibility.