2003 (IPP)
Permanent URI for this collectionhttp://localhost:4000/handle/11007/626
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Item Size of the longest filaments in the Universe(2011-07-05) Bharadwaj, Somnath; Bhavsar, Suketu P.; Sheth, Jatush V.We analyze the filamentarity in the Las Campanas redshift survey (LCRS) and determine the length scale at which filaments are statistically significant. The largest length-scale at which filaments are statistically significant, real objects, is between 70 to 80 h−1 Mpc, for the LCRS −3o slice. Filamentary features longer than 80 h−1 Mpc, though identified, are not statistically significant; they arise from chance alignments. For the five other LCRS slices, filaments of lengths 50 h−1 Mpc to 70 h−1 Mpc are statistically significant, but not beyond. These results indicate that while individual filaments up to 80 h−1 Mpc are statistically significant, the impression of structure on larger scales is a visual effect. On scales larger than 80 h−1 Mpc the filaments interconnect by statistical chance to form the the filament-void network. The reality of the 80 h−1 Mpc features in the −3o slice make them the longest coherent features in the LCRS. While filaments are a natural outcome of gravitational instability, any numerical model attempting to describe the formation of large scale structure in the universe must produce coherent structures on scales that match these observations.Item Morphology of the supercluster-void network in /\ CDM cosmology(2011-07-05) Shandarin, S.F.; Sheth, Jatush V.; Sahni, VarunWe report here the first systematic study of the supercluster-void network in the ΛCDM concordance cosmology in which voids and superclusters are treated on an equal footing. Superclusters are defined as individual members of an over-dense excur- sion set and voids are defined as individual members of a complementary under-dense excursion set at the same density threshold. We determine the geometric, topological and morphological properties of the cosmic web at a large set of density levels by computing Minkowski functionals for every supercluster and void using SURFGEN (Sheth et al. 2003). The properties of the largest (percolating) supercluster and the complementary void are found to be very different from properties of individual su- perclusters and voids. Individual superclusters totally occupy no more than about 5% of the total volume and contain no more than 20% of mass if the largest supercluster is excluded. Likewise, individual voids totally occupy no more than 14% of volume and contain no more than 4% of mass if the largest void is excluded. Although super- clusters are more massive and voids are more voluminous the difference in maximum volumes is not greater than by an order of magnitude. The genus value of individual superclusters can be ∼ 5 while the genus of individual voids can reach ∼ 40, implying significant amount of substructure in superclusters and especially in voids. One of our main results is that large voids, as defined through the density field (read dark matter distribution) can be distinctly non-spherical.