TOOT survey and the largest structure in the universe

Abstract

The Texas-Oxford One Thousand (TOOT) radio source redshift survey is aimed at understanding the evolution of the radio source population down to flux density of S_151MHz = 100 mJy. This low frequency survey has a depth equivalent to about five times the NVSS limit, but does not contain the population of star forming galaxies detected in the NVSS survey. In addition, the survey reaches a high enough surface density of sources on the sky to probe large-scale structure at z ~ 1. Radio sources inhabit massive elliptical galaxies, and as such provide excellent sparse tracers of large-scale structure that are both easily identified and easily observed with spectrographs to map out their space distribution. We review the properties of the TOOT survey and its current status. We also report the discovery, using radio sources, of a huge structure at z=0.27 traced by radio sources and galaxy clusters. Such superstructures are aggregates of clusters seeded by rare (> 3σ) peaks in the power spectrum at recombination. The radio sources and galaxy clusters are shown to trace the same matter distribution. This is the first demonstration of radio AGN as direct sparse tracers of the underlying dark matter distribution. The extent of the superstructure is of order 100 h^-1 Mpc in three dimensions, making it the largest structure known, and indicating a mass similar to that of the Great Attractor. We report the properties of the superstructure, and consider the implications of its existence.