Angular Momentum and the Formation of Stars and Black Holes

TL;DR

This paper discusses how gravitational interactions are crucial in redistributing angular momentum during the formation of stars and black holes, suggesting a complex and dynamic process that influences mass ratios and system properties.

Contribution

It proposes that gravitational interactions with other objects are key to angular momentum redistribution, challenging simpler models of star and black hole formation.

Findings

Gravitational interactions facilitate angular momentum removal.

Formation processes are more dynamic and chaotic than previously thought.

Implications for mass ratios and black hole sizes in galaxies.

Abstract

The formation of compact objects like stars and black holes is strongly constrained by the requirement that nearly all of the initial angular momentum of the diffuse material from which they form must be removed or redistributed during the formation process. The mechanisms that may be involved and their implications are discussed for (1) low-mass stars, most of which probably form in binary or multiple systems; (2) massive stars, which typically form in clusters; and (3) supermassive black holes that form in galactic nuclei. It is suggested that in all cases, gravitational interactions with other stars or mass concentrations in a forming system play an important role in redistributing angular momentum and thereby enabling the formation of a compact object. If this is true, the formation of stars and black holes must be a more complex, dynamic, and chaotic process than in standard models. The gravitational interactions that redistribute angular momentum tend to couple the mass of a forming object to the mass of the system, and this may have important implications for mass ratios in binaries, the upper stellar IMF in clusters, and the masses of supermassive black holes in galaxies.