Accretion disk onto boson stars: a way to supplant black holes candidates

TL;DR

This study compares the emission spectra of accretion disks around black holes and boson stars, showing that certain boson star parameters can mimic black hole spectra, challenging the ability to distinguish them observationally.

Contribution

It demonstrates that boson stars with specific parameters can produce spectra similar to black holes, suggesting they could replace black holes as accreting compact objects.

Findings

Self-interaction and compactness soften the spectrum.

Similar spectra can be produced by boson stars and black holes.

Current models do not distinguish between the two objects.

Abstract

The emission spectrum from a simple accretion disk model around a compact object is compared for the cases of a black hole (BH) and a boson star (BS) playing the role of the central object. It was found in the past that such a spectrum presents a hardening at high frequencies; however, here it is shown that the self-interaction and compactness of the BS have the effect of softening the spectrum, the less compact the star is, the softer the emission spectrum at high frequencies. Because the mass of the boson fixes the mass of the star and the self-interaction the compactness of the star, we find that, for certain values of the BS parameters, it is possible to produce similar spectra to those generated when the central object is a BH. This result presents two important implications: (i) using this simple accretion model, a BS can supplant a BH in the role of compact object accreting matter, and (ii) within the assumptions of the present accretion disk model we do not find a prediction that could help distinguish a BH from a BS with appropriate parameters of mass and self-interaction.