Journal Article

Tracing the first stars with fluctuations of the cosmic infrared background

Moseley, S. H., Kashlinsky, A., Mather, J., Arendt, R. G.

2005

Overview

The deepest space- and ground-based observations find metal-enriched galaxies at cosmic times when the Universe was less than 1 Gyr old. These stellar populations had to be preceded by the metal-free first stars, known as ‘population III’. Recent cosmic microwave background polarization measurements indicate that stars started forming early—when the Universe was ≤200 Myr old. It is now thought that population III stars were significantly more massive than the present metal-rich stellar populations. Although 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; they can be attributed to emission from population III stars, at an era dominated by these objects. Early stars: lifting the veil The most distant and oldest observable stars are in the metal-rich galaxies seen in images such as the Hubble ultra-deep field. The metal — which in cosmology is anything that's not hydrogen or helium — must have come from somewhere and as nucleosynthesis happens in stars, there must have been an earlier population of metal-free stars. No existing or planned telescopes can detect them individually, but evidence of their existence has been found hidden in images obtained by the Infrared Array Camera onboard NASA's Spitzer Space Telescope. After removing foreground stars and galaxies from the image, the tiny fluctuations that remain in the cosmic infrared background are the fossil of emissions from the old metal-free stars.

• Publisher: Nature Publishing Group UK,Nature Publishing,Nature Publishing Group
• Subject: Astronomy / Background radiation / Background radiations / Cosmic microwave background temperature / Cosmology / Earth, ocean, space / Exact sciences and technology / Fluctuations / Humanities and Social Sciences / multidisciplinary / Normal stars (by class): general or individual / Population iii stars / Science / Science (multidisciplinary) / Stars / Stars & galaxies / Stellar systems. Galactic and extragalactic objects and systems. The universe / Unidentified sources and radiation outside the solar system / Universe