Detection of Pristine Gas Two Billion Years after the Big Bang

TL;DR

This paper reports the discovery of two ancient gas clouds with no detectable heavy elements, providing evidence for pristine gas from the early universe and confirming predictions of primordial nucleosynthesis.

Contribution

It presents the first detection of nearly pristine gas clouds from two billion years after the Big Bang, confirming the standard cosmological model's predictions.

Findings

Detection of two gas clouds with no heavy elements

Presence of deuterium matching primordial nucleosynthesis levels

Evidence of inhomogeneous distribution of heavy elements

Abstract

In the current cosmological model, only the three lightest elements were created in the first few minutes after the Big Bang; all other elements were produced later in stars. To date, however, heavy elements have been observed in all astrophysical environments. We report the detection of two gas clouds with no discernible elements heavier than hydrogen. These systems exhibit the lowest heavy-element abundance in the early universe and thus are potential fuel for the most metal poor halo stars. The detection of deuterium in one system at the level predicted by primordial nucleosynthesis provides a direct confirmation of the standard cosmological model. The composition of these clouds further implies that the transport of heavy elements from galaxies to their surroundings is highly inhomogeneous.