The Clowes-Campusano Large Quasar Group Survey: I. GALEX selected sample of LBGs at z$\sim$1

TL;DR

This study investigates large-scale galaxy structures at z~1 using GALEX and SDSS data, identifying LBG candidates and analyzing their properties and overdensities within quasar groups, revealing evolved stellar populations and clustering similar to higher redshift LBGs.

Contribution

First analysis of LBGs in large quasar groups at z~1 using GALEX and SDSS data, revealing their spectral properties and clustering behavior.

Findings

LBGs at z~1 have flat spectral energy distributions indicating evolved stars.

Overdensities of LBGs are detected in quasar groups compared to foreground regions.

LBG clustering scales at z~1 are similar to those at z~3.

Abstract

The nature of galaxy structures on large scales is a key observational prediction for current models of galaxy formation. The SDSS and 2dF galaxy surveys have revealed a number of structures on 40-150 h^-1 Mpc scales at low redshifts, and some even larger ones. To constrain galaxy number densities, luminosities, and stellar populations in large structures at higher redshift, we have investigated two sheet-like structures of galaxies at z=0.8 and 1.3 spanning 150 h^-1 comoving Mpc embedded in large quasar groups extending over at least 200 h^-1 Mpc. We present first results of an analysis of these sheet--like structures using two contiguous 1deg GALEX fields (FUV and NUV) cross-correlated with optical data from the Sloan Digital Sky Survey (SDSS). We derive a sample of 462 Lyman Break Galaxy (LBG) candidates coincident with the sheets. Using the GALEX and SDSS data, we show that the overall average spectral energy distribution of a LBG galaxy at z~1 is flat (in f_lambda) in the rest frame wavelength range from 1500A, to 4000A, implying evolved populations of stars in the LBGs. From the luminosity functions we get indications for overdensities in the two LQGs compared to their foreground regions. Similar conclusions come from the calculation of the 2-point correlation function, showing a 2sigma overdensity for the LBGs in the z~0.8 LQG on scales of 1.6 to 4.8 Mpc, indicating similar correlation scales for our LBG sample as their z~3 counterparts.