  The deepest space and ground-based observations find metal-enriched galaxies
at cosmic times when the Universe was <1 Gyr old. These stellar populations had
to be preceded by the metal-free first stars, Population III. Recent cosmic
microwave background polarization measurements indicate that stars started
forming early when the Universe was $\lsim200$ Myr old. Theoretically it is now
thought that Population III stars were significantly more massive than the
present metal-rich stellar populations. While such sources will not be
individually detectable by existing or planned telescopes, they would have
produced significant cosmic infrared background radiation in the near-
infrared, whose fluctuations reflect the conditions in the primordial density
field. Here we report a measurement of diffuse flux fluctuations after removing
foreground stars and galaxies. The anisotropies exceed the instrument noise and
the more local foregrounds and can be attributed to emission from massive
Population III stars, providing observational evidence of an era dominated by
these objects.
