QUASARS AND LARGE SCALE STRUCTURE OF THE UNIVERSE

The majority of bright distant quasars $(z {}^{>}_{\sim} 1)$ may form in massive mergers appearing in compact galaxy groups in/and young clusters. The expected tests are (i) large correlation signal for medium-$z$ QSOs $(1 < z < 2)$ and (ii) direct search for quasar groups (QGs) indicating positions of distant pre-superclusters which later will evolve to the "systems" like the local Great Attractor or Shapley concentration. We discuss large QGs with more than ten members within regions $\le l_{LS} \sim 100-150 \, h^{-1} Mpc$, tracing the enhanced density regions at $z {}^{<}_{\sim} 2$. These early large scale structures (i) provide a natural way to "bias" the distribution of Abell clusters, and (ii) suggest that the spectrum of primordial density perturbations is nearly flat at scales encompassing both cluster and GAs, $l = \pi k^{-1} \in(10,100)h^{-1} Mpc: \Delta^{2}_{k} \sim k^{3}P(k) \sim k^{\gamma}, \gamma = 1^{+0.6}_{-0.4}$.Comment: 5 pages, uuencoded Z-compressed postscript, contribution to the Proceedings of Rencontres de Moriond 1995 "Clustering in the Universe

A Semi-automatic Search for Giant Radio Galaxy Candidates and their Radio-Optical Follow-up

We present results of a search for giant radio galaxies (GRGs) with a projected largest linear size in excess of 1 Mpc. We designed a computational algorithm to identify contiguous emission regions, large and elongated enough to serve as GRG candidates, and applied it to the entire 1.4-GHz NRAO VLA Sky survey (NVSS). In a subsequent visual inspection of 1000 such regions we discovered 15 new GRGs, as well as many other candidate GRGs, some of them previously reported, for which no redshift was known. Our follow-up spectroscopy of 25 of the brighter hosts using two 2.1-m telescopes in Mexico, and four fainter hosts with the 10.4-m Gran Telescopio Canarias (GTC), yielded another 24 GRGs. We also obtained higher-resolution radio images with the Karl G. Jansky Very Large Array for GRG candidates with inconclusive radio structures in NVSS.Comment: 4 pages, 1 figure, to appear in the proceedings of The Universe of Digital Sky Surveys, Naples, Italy, Nov 25-28, 2014; Astrophysics and Space Science, eds. N.R. Napolitano et a