The Super-Eddington Nature of Super Massive Stars

TL;DR

This paper investigates supermassive stars near the Eddington limit, revealing their evolution, mass loss, and potential to form supermassive black holes, emphasizing the role of porosity and rotation in their lifecycle.

Contribution

It introduces a detailed analysis of super-Eddington states in supermassive stars, highlighting the effects of porosity, rotation, and winds on their evolution and end states.

Findings

Supermassive stars evolve faster due to increased energy release.

Continuum-driven winds accelerate mass loss in SMSs.

Without rotational stabilization, winds do not prevent collapse into black holes.

Abstract

Supermassive stars (SMS) are massive hydrogen objects, slowly radiating their gravitational binding energy. Such hypothetical primordial objects may have been the seed of the massive black holes (BHs) observed at the centre of galaxies. Under the standard picture, these objects can be approximately described as n=3 polytropes, and they are expected to shine extremely close to their Eddington luminosity. Once however, one considers the porosity induced by instabilities near the Eddington limit, which give rise to super-Eddington states, the standard picture should be modified. We study the structure, evolution and mass loss of these objects. We find the following. First, the evolution of SMSs is hastened due to their increased energy release. They accelerate continuum driven winds. If there is no rotational stabilization, these winds are insufficient to "evaporate" the objects, such that they can collapse to form a supermassive BHs, however, they do prevent SMSs from emitting a copious amount of ionizing radiation. If the SMSs are rotationally stabilized, the winds "evaporate" the objects until a normal sub-Eddington star remains, having a mass of a few 100Msun.