Oxygen-enhanced extremely metal-poor DLAs: A signpost of the first stars?

Abstract

We present precise abundance determinations of two near-pristine damped Ly$\alpha$ systems (DLAs) to assess the nature of the [O/Fe] ratio at [Fe/H] < -3 (i.e. <1/1000 of the solar metallicity). Prior observations indicate that the [O/Fe] ratio is consistent with a constant value, [O/Fe] ~ +0.4, when -3 < [Fe/H] < -2, but this ratio may increase when [Fe/H] < -3. In this paper, we test this picture by reporting new, high-precision [O/Fe] abundances in two of the most metal-poor DLAs currently known. We derive values of [O/Fe] = +0.50 +/- 0.10 and [O/Fe] = +0.62 +/- 0.05 for these two z ~ 3 near-pristine gas clouds. These results strengthen the idea that the [O/Fe] abundances of the most metal-poor DLAs are elevated compared to DLAs with [Fe/H] > -3. We compare the observed abundance pattern of the latter system to the nucleosynthetic yields of Population III supernovae (SNe), and find that the enrichment can be described by a (19-25) M${}_{\odot }$ Population III SN that underwent a (0.9-2.4)$\times 10^{51}$ erg explosion. These high-precision measurements showcase the behaviour of [O/Fe] in the most metal-poor environments. Future high-precision measurements in new systems will contribute to a firm detection of the relationship between [O/Fe] and [Fe/H]. These data will reveal whether we are witnessing a chemical signature of enrichment from Population III stars and allow us to rule out contamination from Population II stars.

16 pages, 9 figures, accepted for publication in ApJ

References in corpus (18)

• The NumPy array: a structure for efficient numerical computation
• The DESI Experiment Part I: Science,Targeting, and Survey Design
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• Pulsational Pair-Instability Supernovae
• Nucleosynthetic signatures of the first stars
• Metallicity Evolution of Damped Lyman-alpha Systems out to z~5
• Effects of rotation on the evolution of primordial stars
• C, N, O Abundances in the Most Metal-Poor Damped Lyman alpha Systems
• The primordial deuterium abundance of the most metal-poor damped Lyman-alpha system
• The Cosmic Evolution of the Metallicity Distribution of Ionized Gas Traced by Lyman Limit Systems
• Evidence for an aspherical Population III supernova explosion inferred from the hyper metal-poor star HE1327-2326
• PUSHing core-collapse supernovae to explosions in spherical symmetry IV: Explodability, remnant properties and nucleosynthesis yields of low metallicity stars
• The Nitrogen and Oxygen abundances in the neutral gas at high redshift
• Discovery of the most metal-poor damped Lyman-alpha system
• Chemical abundances of damped Lyman alpha systems in the XQ-100 survey
• The most metal-poor damped Ly alpha system at z<3: constraints on early nucleosynthesis
• WEAVE-QSO: A Massive Intergalactic Medium Survey for the William Herschel Telescope
• Three-dimensional hydrodynamical CO5BOLD model atmospheres of red giant stars. IV. Oxygen diagnostics in extremely metal-poor red giants with infrared OH lines