Taking off the edge - simultaneous filament and end core formation

Abstract

Simulations of idealized star-forming filaments of finite length typically show core growth that is dominated by two cores forming at its respective end. The end cores form due to a strong increasing acceleration at the filament ends that leads to a sweep-up of material during the filament collapse along its axis. As this growth mode is typically faster than any other core formation mode in a filament, the end cores usually dominate in mass and density compared to other cores forming inside a filament. However, observations of star-forming filaments do not show this prevalence of cores at the filament ends. We explore a possible mechanism to slow the growth of the end cores using numerical simulations of simultaneous filament and embedded core formation, in our case a radially accreting filament forming in a finite converging flow. While such a set-up still leads to end cores, they soon begin to move inwards and a density gradient is formed outside of the cores by the continued accumulation of material. As a result, the outermost cores are no longer located at the exact ends of the filament and the density gradient softens the inward gravitational acceleration of the cores. Therefore, the two end cores do not grow as fast as expected and thus do not dominate over other core formation modes in the filament.