Accretion of Supersonic Winds on Boson Stars

TL;DR

This study investigates how supersonic winds interact with Boson Stars compared to Black Holes, revealing differences in density profiles and potential observational signatures to distinguish these objects.

Contribution

It provides the first detailed comparison of wind accretion onto Boson Stars versus Black Holes, highlighting key physical differences and conditions affecting their observational appearance.

Findings

Wind achieves stationary flux around Boson Stars

Maximum gas density is lower in Boson Stars than in Black Holes

High self-interaction and compactness in Boson Stars increase similarity to Black Holes

Abstract

We present the evolution of a supersonic wind interacting with a Boson Star (BS) and compare the resulting wind density profile with that of the shock cone formed when the wind is accreted by a non-rotating Black Hole (BH) of the same mass. The physical differences between these accretors are that a BS, unlike a BH has no horizon, it does not have a mechanical surface either and thus the wind is expected to trespass the BS. Despite these conditions, on the BS space-time the gas achieves a stationary flux with the gas accumulating in a high density elongated structure comparable to the shock cone formed behind a BH. The highest density resides in the center of the BS whereas in the case of the BH it is found on the downstream part of the BH near the event horizon. The maximum density of the gas is smaller in the BS than in the BH case. Our results indicate that the highest density of the wind is more similar on the BS to that on the BH when the BS has high self-interaction, when it is more compact and when the wind velocity is higher. We expect this and similar analyses help to know whether BSs can still be Black Hole mimickers or can be ruled out.