The spatial fluctuations of the extragalactic background light trace the total emission from all stars and galaxies in the Universe. A multiwavelength study can be used to measure the integrated emission from first galaxies during reionization when the Universe was about 500 million years old. Here we report arcmin-scale spatial fluctuations in one of the deepest sky surveys with the Hubble Space Telescope in five wavebands between 0.6 and 1.6 μm. We model-fit the angular power spectra of intensity fluctuation measurements to find the ultraviolet luminosity density of galaxies at redshifts greater than 8 to be log ρUV = 27.4+0.2-1.2ergs-1Hz-1Mpc-3(1σ). This level of integrated light emission allows for a significant surface density of fainter primeval galaxies that are below the point-source detection level in current surveys.
This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. A.C. acknowledges support from NSF CAREER AST-06455427, AST-1310310, and STScI Archival Research program.
Mitchell-Wynne, Ketron; Cooray, Asantha; Gong, Yan; Ashby, Matthew; Dolch, Timothy; Ferguson, Henry; Finkelstein, Steven; Grogin, Norman; Kocevski, Dale D.; Koekemoer, Anton; Primack, Joel; and Smidt, Joseph, "Ultraviolet Luminosity Density of the Universe During the Epoch of Reionization" (2015). Physics and Astronomy Faculty Publications. 360.