Void Galaxy Distribution: A Challenge for ΛCDM

We extract void catalogs from the Sloan Digital Sky Survey Data Release 16 (SDSS DR16) survey and also from the Millennium simulation. We focus our comparison on distribution of galaxies brighter than M ( r ) < -18 inside voids and study the mean separation of void galaxies, distance from the void center, and the radial density profile. We find that mean separation of void galaxies depends on void size, as bigger voids have lower mean separation in both samples. However, void galaxies in the observation sample seem to have generally larger mean-distance than simulated ones at any given void size. In addition, observed void galaxies tend to reside closer to the void center than those in the simulation. This discrepancy is also shown in the density profile of voids. Regardless of the void size, the central densities of real void profiles are higher than the ones in the predicted simulated catalog.

Automated summary

The study found that the mean separation of void galaxies is influenced by void size, with larger voids having lower mean separation in both the observation and simulation samples. Void galaxies in the observation sample tend to have generally larger mean-distance than those in the simulated sample at any given void size, and they also tend to reside closer to the void center.