Gravitational instability of non-isothermal filamentary molecular clouds, in presence of external pressure

TL;DR

This study investigates the gravitational stability of non-isothermal, pressure-confined filamentary molecular clouds under magnetic influence, revealing how filament thickness and magnetic field strength affect their stability.

Contribution

It provides a comprehensive stability analysis of non-isothermal filaments with magnetic fields using large parameter surveys, highlighting the stabilizing effects of magnetic fields on different filament types.

Findings

Thinner filaments are more sensitive to magnetic field variations.

Intermediate magnetic fields can stabilize thinner filaments.

Strong magnetic fields (>70 μG) suppress stabilization in thicker filaments.

Abstract

Filamentary molecular clouds are omnipresent in the cold interstellar medium. Observational evidences show that the non-isothermal equations of state describe the filaments properties better than the isothermal one. In this paper we use the logatropic and the polytropic equations of state to study the gravitational instability of the pressure-confined filaments in presence of a uniform axial magnetic field. To fully explore the parameter space we carry out very large surveys of stability analysis that cover filaments with different radii in various magnetic fields. Our results show that for all the equations of state the instability of thinner filaments is more sensitive to the magnetic field variations than the thicker ones. Moreover, for all the equations of state, an intermediate magnetic field can entirely stabilize the thinner filaments. Albeit for the thicker ones this effect is suppressed for the magnetic field stronger than B ' 70 micro G.