  Extragalactic background light (EBL) anisotropy traces variations in the
total production of photons over cosmic history, and may contain faint,
extended components missed in galaxy point source surveys. Infrared EBL
fluctuations have been attributed to primordial galaxies and black holes at the
epoch of reionization (EOR), or alternately, intra-halo light (IHL) from stars
tidally stripped from their parent galaxies at low redshift. We report new EBL
anisotropy measurements from a specialized sounding rocket experiment at 1.1
and 1.6 micrometers. The observed fluctuations exceed the amplitude from known
galaxy populations, are inconsistent with EOR galaxies and black holes, and are
largely explained by IHL emission. The measured fluctuations are associated
with an EBL intensity that is comparable to the background from known galaxies
measured through number counts, and therefore a substantial contribution to the
energy contained in photons in the cosmos.
