Two close large quasar groups of size ~ 350 Mpc at z ~ 1.2
Monthly Notices of the Royal Astronomical Society (2012), 419, 556.
Two Close Large Quasar Groups of Size ~ 350 Mpc at z ~ 1.2
Roger G. Clowes1, Luis E. Campusano2, Matthew J. Graham3, Ilona K. Söchting4
1 Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
2Observatorio Astronómico Cerro Calán, Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
3California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
4Astrophysics, Denys Wilkinson Building, Keble Road, University of Oxford, Oxford OX1 3RH, UK
The Clowes & Campusano large quasar group (LQG) at <z> = 1.28 has been re-examined using the quasar data from the DR7QSO catalogue of the Sloan Digital Sky Survey. In the 1991 discovery, the LQG impinged on the northern, southern and eastern limits of the survey. In the DR7QSO data, the western, northern and southern boundaries of the LQG remain essentially the same, but an extension eastwards of ∼ 2 deg is indicated. In the DR7QSO data, the LQG has 34 members, with <z> = 1.28. A new group of 38 members is indicated at <z> = 1.11 and within ~ 2.0 deg of the Clowes & Campusano LQG. The characteristic sizes of these two LQGs, ∼350–400 Mpc, appear to be only marginally consistent with the scale of homogeneity in the concordance cosmology. In addition to their intrinsic interest, these two LQGs provide locations in which to investigate early large-scale structure in galaxies and to identify high-z clusters. A method is presented for assessing the statistical significance and overdensity of groups found by linkage of points.
This work has used the SDSS DR7QSO catalogue (Schneider et al. 2010) and the SDSS spectra.
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