We investigate the idea that the interaction of Dark Matter ( DM ) sub-halos with the gaseous disk of galaxies can be the origin for the observed holes and shells found in their neutral hydrogen ( HI ) distributions .
We use high resolution hydrodynamic simulations to show that pure DM sub-halos impacting a galactic disk are not able to produce holes ; on the contrary , they result in high density regions in the disk .
However , sub-halos containing a small amount of gas ( a few percent of the total DM mass of the sub-halo ) are able to displace the gas in the disk and form holes and shells .
The size and lifetime of these holes depend on the sub-halo gas mass , density and impact velocity .
A DM sub-halo of mass 10 ^ { 8 } M _ { \odot } and a gas mass fraction of \sim 3 \% , is able to create a kpc scale hole , with a lifetime similar to those observed in nearby galaxies .
We also register an increase in the star formation rate at the rim of the hole , again in agreement with observations .
Even though the properties off these simulated structures resemble those found in observations we find that the number of predicted holes ( based on mass and orbital distributions of DM halos derived from cosmological N-body simulations ) falls short compared to the observations .
Only a handful of holes are produced per Giga year .
This leads us to conclude that DM halo impact is not the major channel through which these holes are formed .