Implications of a non-universal IMF from C, N, and O abundances in very metal-poor Galactic stars and damped Lyman-alpha absorbers

Abstract

Recently revealed C, N, and O abundances in the most metal-poor damped Lyman-alpha (DLA) absorbers are compared with those of extremely metal-poor stars in the Galactic halo, as well as extragalactic H II regions, to decipher nucleosynthesis and chemical enrichment in the early Universe. These comparisons surprisingly identify a relatively high C/O ratio and a low N/O ratio in DLA systems, which is hard to explain theoretically. We propose that if these features are confirmed by future studies, this effect occurs because the initial mass function in metal-poor DLA systems has a cut-off at the upper mass end at around 20-25 Msun, thus lacks the massive stars that provide the nucleosynthesis products leading to the low C/O and high N/O ratios. This finding is a reasonable explanation of the nature of DLA systems in which a sufficient amount of cold H I gas remains intact because of the suppression of ionization by massive stars. In addition, our claim strongly supports a high production rate of N in very massive stars, which might be acceptable in light of the recent nucleosynthesis calculations with fast rotation models. The updates of both abundance data and nucleosynthesis results will strengthen our novel proposition that the C/O and N/O abundances are a powerful tool for inferring the form of the initial mass function.

9 pages including 5 figures, accepted for publication in A&A

References in corpus (9)

• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production
• Effects of rotation on the evolution of primordial stars
• A strong case for fast stellar rotation at very low metallicities
• C, N, O Abundances in the Most Metal-Poor Damped Lyman alpha Systems
• Formation & evolution of the Galactic bulge: constraints from stellar abundances
• The Nitrogen and Oxygen abundances in the neutral gas at high redshift
• The Chemical Evolution Of High Z Galaxies From The Relative Abundances Of N, Si, S, And Fe In Damped Lyman Alpha Systems
• On Iron Enrichment, Star Formation, and Type Ia Supernovae in Galaxy Clusters

Cited by in corpus (7)

• The most metal-poor damped Lyman-alpha systems: Insights into chemical evolution in the very metal-poor regime
• Carbon and Oxygen Abundances in Low Metallicity Dwarf Galaxies
• ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo~P. III. An Extremely Metal Deficient Galaxy
• Chemical Signature Indicating A Lack of Massive Stars in Dwarf Galaxies
• SOFIA observations of far-IR fine-structure lines in galaxies to measure metallicity
• The impact of carbon and oxygen abundances on the metal-poor initial mass function
• Stripping of nitrogen-rich AGB ejecta from interacting dwarf irregular galaxies