Void Galaxy Distribution: A Challenge for ?CDM

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