A new candidate for probing Population III nucleosynthesis with carbon-enhanced damped Lyman-alpha systems

TL;DR

This paper reports the discovery of a very metal-poor, carbon-enhanced damped Lyman-alpha system at high redshift, which could provide insights into Population III star nucleosynthesis, though current data cannot definitively distinguish the origin.

Contribution

It presents the first identification of a carbon-enhanced, metal-poor DLA with potential signatures of Population III nucleosynthesis, highlighting observational challenges and future prospects.

Findings

Identified a DLA with [Fe/H] = -2.84 and [C,O/Fe] ~ +0.6.

Derived an upper temperature limit of T_DLA <= 4700 K.

Models of high-mass Population II stars can replicate the observed abundance pattern.

Abstract

We report the identification of a very metal-poor damped Lyman-alpha system (DLA) at z_abs = 3.067295 that is modestly carbon-enhanced, with an iron abundance of ~1/700 solar ([Fe/H] = -2.84) and [C,O/Fe] ~ +0.6. Such an abundance pattern is likely to be the result of nucleosynthesis by massive stars. On the basis of 17 metal absorption lines, we derive a 2 sigma upper limit on the DLA's kinetic temperature of T_DLA <= 4700 K, which is broadly consistent with the range of spin temperature estimates for DLAs at this redshift and metallicity. While the best-fitting abundance pattern shows the expected hallmarks of Population III nucleosynthesis, models of high-mass Population II stars can match the abundance pattern almost as well. We discuss current limitations in distinguishing between these two scenarios and the marked improvement in identifying the remnants of Population III stars expected from the forthcoming generation of 30-metre class telescopes.