Formation of filaments/feathers in disc galaxies: Is self-gravity enough?

Dense filaments/feathers are kpc scale dusty features found in nearby main sequence disc galaxies. Visible as dust-attenuated features in HST and recently seen in emission maps of JWST/MIRI images in unprecedented detail. They are known to harbor embedded star forming regions, giving us insight into early stages of star formation and are expected to play an important role in molecular cloud formation as well. We explore the origin of these galactic filaments via the action of a global gravitational instability. Using 3D high resolution numerical simulations of isolated disc galaxies, we demonstrate that self-gravity alone is able to form galactic filaments without the need for spiral lanes, magnetic fields or feedback from stars. Their morphological properties, as well as their timescales of formation are found to vary with the thermodynamical and rotational properties of the disc. This is characterised by the dimensionless ratio vc/cs (ratio of the saturated circular velocity to the sound speed) of the galaxy. We also quantify the spacing of the filaments using a 2D Fourier transform and compare them with JWST and HST observations of nearby galaxies and find them to be in good agreement.