Triggered fragmentation in self-gravitating discs: forming fragments at small radii

TL;DR

This study uses 3D radiation hydrodynamical simulations to show that fragmentation in self-gravitating discs can lead to inward mass movement, potentially causing further fragmentation at smaller radii after initial outer disc fragmentation.

Contribution

It reveals how mass movement after initial fragmentation influences subsequent fragmentation at smaller radii in self-gravitating discs.

Findings

Radial gas velocity increases up to 10 times after fragmentation.

Inward mass flow can cause inner disc regions to become dense enough to fragment.

Fragmentation can occur at smaller radii due to dynamical effects post initial fragmentation.

Abstract

We carry out three dimensional radiation hydrodynamical simulations of gravitationally unstable discs to explore the movement of mass in a disc following its initial fragmentation. We find that the radial velocity of the gas in some parts of the disc increases by up to a factor of approximately 10 after the disc fragments, compared to before. While the movement of mass occurs in both the inward and outward directions, the inwards movement can cause the inner spirals of a self-gravitating disc to become sufficiently dense such that they can potentially fragment. This suggests that the dynamical behaviour of fragmented discs may cause subsequent fragmentation to occur at smaller radii than initially expected, but only after an initial fragment has formed in the outer disc.