Influence of the relict cosmological constant on accretion discs

TL;DR

The paper explores how the relict cosmological constant influences the structure and behavior of accretion discs around black holes, affecting their size, outflows, and jet collimation in quasars and active galactic nuclei.

Contribution

It demonstrates the significant impact of the relict cosmological constant on accretion disc properties in Kerr-de Sitter spacetimes, a novel consideration in astrophysical models.

Findings

Accretion discs have an outer edge near the static radius where matter outflows occur.

Jets from thick discs can become highly collimated after crossing the static radius.

The extension of quasar discs may be limited by the cosmological constant, comparable to galaxy sizes.

Abstract

Surprisingly, the relict cosmological constant has a crucial influence on properties of accretion discs orbiting black holes in quasars and active galactic nuclei. We show it by considering basic properties of both the geometrically thin and thick accretion discs in the Kerr-de Sitter black-hole (naked-singularity) spacetimes. Both thin and thick discs must have an outer edge allowing outflow of matter into the outer space, located nearby the so called static radius, where the gravitational attraction of a black hole is balanced by the cosmological repulsion. Jets produced by thick discs can be significantly collimated after crossing the static radius. Extension of discs in quasars is comparable with extension of the associated galaxies, indicating a possibility that the relict cosmological constant puts an upper limit on extension of galaxies.