Effects of magnetic fields on the formation of Interstellar Filaments through shock-cloud interaction

Abstract

Interstellar Filaments are ubiquitous in molecular clouds which are hotbeds for star birth. What leads to their formation has been a subject of study in recent years. In the present numerical experiment, we have looked into the role of magnetic field in formation of such structures in the context of multiple molecular cloud complexes after they were subjected to a passing shock. We found that in the absence of this field, post-shock region is turbulent, leading to higher material mixing, 17.5% in the case of the highest porous model considered which also had 42% higher area filling factor compared to models with magnetic field imposed. On the other hand in the presence of a magnetic field, processes such as ‘mass-loading’, slowing down of shock, and inhibition of instabilities are observed which we have found to facilitate the formation of less porous and hence more clumpy structures in post-shock regions. It is found that in the absence of a field, such structures are diffused and spread over a larger area. Such structures are later elongated by hydrodynamical ablation leading to filament-like structures. Morphological output images having filamentary structures are further studied using tools from Nonlinear Dynamics such as Percolation and Fractal Analysis. We find that the filaments formed without a field have higher fractal dimensions, are longer, more complex, and highly branched. Magnetic field influences the properties of the filaments, making them smaller, more confined, and less complex. Further, it is observed that the influence of B is diminished with the presence of radiative cooling, still having a subtle affect on the system’s evolution though.