Understanding ULX Nebulae in the Framework of Supercritical Accretion

TL;DR

This paper models ULX nebulae using SS433 as a prototype, explaining their properties through supercritical accretion and jet activity over evolutionary timescales of up to a million years.

Contribution

It demonstrates that ULX nebulae can be explained by SS433-like systems evolving in a constant density environment, highlighting the role of jets and shock waves.

Findings

ULX nebulae properties can be modeled by SS433-like systems.

Evolutionary stages include non-spherical HII regions and bipolar shock nebulae.

Most ULX nebulae can be explained within about one million years.

Abstract

For a long time, the well-known supercritically accreting binary SS433 is being proposed as a prototype for a class of hypothetical bright X-ray sources that may be identified with the so-called Ultraluminous X-ray sources (ULXs) in nearby galaxies or at least with part of them. Like SS433, these objects should be associated with optical nebulae, powered by both radiation of the central source and its wind or jet activity. Indeed, around many ULXs, bright optical nebulae (ULX Nebulae, ULXNe) are found. Here, we use SS433 as a prototype for the power source creating the nebulae around ULXs. Though many factors are important such as the structure of the host star-forming region and the possible supernova remnant formed together with the accreting compact object, we show that most of the properties of ULXNe may be explained by an SS433-like system evolving for up to about one million years in a constant density environment. The basic stages of evolution of a ULX Nebula include a non-spherical HII-region with a central cavity created by non-radiative shock waves, an elongated or bipolar shock-powered nebula created by jet activity and a large-scale quasi-spherical bubble.