Author(s): Asantha Cooray1
Institution(s): 1. University of California, Irvine
The spatial fluctuations of the extragalactic background light (EBL) trace the total emission from unresolved stars and galaxies in the Universe. Due to redshifting of the photons arising from sources present during reionization, their emission is expected to peak in the 0.9 to 1.1 micron wavelength regime with no contribution shortward of the redshifted Lyman break around 0.8 micron. Spatial fluctuations of the EBL centered around 1micron thus provide the best mechanism to separate the signal generated by galaxies present during reionization from those at lower redshifts, such as faint nearby galaxies and the intra-halo light. Previous measurements of fluctuations in the EBL have until now been limited to wavelengths greater than 1.1 micron with the best measurements performed at 3.6 micron. We will present arcminute-scale spatial fluctuations of the optical and near-IR background from 0.5 micron to 4.5 microns using a combination of Hubble/CANDELS, Spitzer, and CIBER data. We will reveal resulting constraints on reionization and the UV luminosity density of the universe at z > 8 during the epoch of reionization. Our estimate of the UV luminosity density at z > 8 is consistent with the integrated intensity from extrapolations related to current drop-out detections and leaves open the possibility for a significant surface density of fainter galaxies that are undetected in current surveys.