1210.2432 (Saeed Tavasoli et al.)

The challenge of large and empty voids in SDSS DR7 redshift survey    [PDF]

Saeed Tavasoli, Kaveh Vasei, Roya Mohayaee

We produce catalogues of voids for SDSS DR7 redshift survey and for a Millennium I simulation mock data. The mock catalog is constructed such that it closely represents SDSS DR7 survey. We carry a parallel analysis of the two catalogues and find that in both the observation and the simulation, voids tend to be equally spherical. The total volume occupied by the voids and their total number are slightly larger in the simulation than in the observation. We find that large voids are less abundant in the simulation and the total luminosity of the galaxies contained in a void with a given radius is on average higher than observed by SDSS DR7 survey. We expect these discrepancies to be, in fact, even more important than found here since the present value of $\sigma_8$ given by WMAP7 is lower than the value of 0.9 used in the Millennium I simulation. The reason why the simulation fails to produce enough of the large and dark voids could be due to the failure of certain semi-analytic models of galaxy formation in reducing the small-scale power of $\Lambda$CDM and in producing sufficient power on large scales.

View original: http://arxiv.org/abs/1210.2432