Future virialized structures: An analysis of superstructures in SDSS-DR7
  We construct catalogues of present superstructures that, according to a LCDM
scenario, will evolve into isolated, virialized structures in the future. We
use a smoothed luminosity density map derived from galaxies in SDSS-DR7 data
and separate high luminosity density peaks. The luminosity density map is
obtained from a volume-limited sample of galaxies in the spectroscopic galaxy
catalogue, within the SDSS-DR7 footprint area and in the redshift range 0.04 <
z < 0.12. Other two samples are constructed for calibration and testing
purposes, up to z = 0.10 and z = 0.15. The luminosity of each galaxy is spread
using an Epanechnikov kernel of 8Mpc/h radius, and the map is constructed on a
1 Mpc/h cubic cells grid. Future virialized structures (FVS) are identified as
regions with overdensity above a given threshold, calibrated using a LCDM
numerical simulation, and the criteria presented by D\"unner et al. (2006). We
assume a constant mass-to-luminosity ratio and impose the further condition of
a minimum luminosity of 10^{12}Lsol. According to our calibrations with a
numerical simulation, these criteria lead to a negligible contamination by less
overdense (non FVS) superstructures.We present a catalogue of superstructures
in the SDSS-DR7 area within redshift 0.04 < z < 0.12 and test the reliability
of our method by studying different subsamples as well as a mock catalogue.We
compute the luminosity and volume distributions of the superstructures finding
that about 10% of the luminosity (mass) will end up in future virialized
structures. The fraction of groups and X-ray clusters in these superstructures
is higher for groups/clusters of higher mass, suggesting that future cluster
mergers will involve the most massive systems. We also analyse known structures
in the present Universe and compare with our catalogue of FVS.
