Perturbation growth in accreting filaments

TL;DR

This study uses simulations to analyze how perturbations grow in accreting filaments, revealing complex growth patterns influenced by accretion rate and temperature, and providing insights into filament fragmentation and core formation.

Contribution

It introduces a detailed dispersion relation for perturbation growth in accreting filaments, accounting for gravo-acoustic oscillations and linking growth rates to physical conditions.

Findings

Growth peaks depend on accretion rate and temperature.

Preferred core separation matches the largest dispersion relation peak.

Model estimates filament age and maximum accretion rate.

Abstract

We use smoothed particle hydrodynamic simulations to investigate the growth of perturbations in infinitely long, initially sub-critical but accreting filaments. The growth of these perturbations leads to filament fragmentation and the formation of cores. Most previous work on this subject has been confined to the growth and fragmentation of equilibrium filaments and has found that there exists a preferential fragmentation length scale which is roughly 4 times the filament's diameter. Our results show a more complicated dispersion relation with a series of peaks linking perturbation wavelength and growth rate. These are due to gravo-acoustic oscillations along the longitudinal axis during the sub-critical phase of growth. The positions of the peaks in growth rate have a strong dependence on both the mass accretion rate onto the filament and the temperature of the gas. When seeded with a multi-wavelength density power spectrum there exists a clear preferred core separation equal to the largest peak in the dispersion relation. Our results allow one to estimate a minimum age for a filament which is breaking up into regularly spaced fragments, as well as a maximum accretion rate. We apply the model to observations of filaments in Taurus by Tafalla & Hacar (2015) and find accretion rates consistent with those estimated by Palmeirim et al. (2013).