Environmental influence of voids on dark matter halos
Cosmic voids represent ideal environments to study the formation and evolution of galaxies and dark matter halos. In this project, we described the void environment and studied how the void halos differ than the overall halo population. The study is based on a GADGET-2 N-body simulation. The voids within the simulation have been identified using the Watershed Void Finder. The halos have been identified in the particle distribution using the Rockstar Halo Finder. To specifically find void halos, the convex hull algorithm was implemented.
We found that voids have a characteristic size of 17 Mpc and tend to be more prolate in shape. A correlation between the sizes and shapes of voids suggest that larger voids tend to be more round. We computed the density profiles which indicate that voids present underdense interiors and are surrounded by high density ridges. We also calculated the velocity profiles and showed that in the interior of voids, velocity increases linearly. At further radii, a drastic increase in velocity develops followed by a decline. Once the void environment was characterized, we turn to the halo analysis. We investigated the halo abundance and found that the percentage of halos residing within voids is ~11%. The halo mass function revealed that void halos present lower masses than the overall halo population. We also show that there exists a systematic decreasing trend of the spin of void halos as a function of their distance from the void boundary. Similarly, the shapes of the void halos located closer to the void centers reveal that they are slightly flattener than their overall counterparts.