2020/05/31 by Arpita Roy, A.B. Roy, Michael A. Dopita +5 · 27 citations
Physics and Astronomy · #Abundance (ecology) #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Chemical evolution #Dwarf galaxy #Ejecta #Galaxy #Gamma-ray bursts and supernovae #Interstellar medium #Metallicity #Physics #Redshift #Star formation #Stars #Stellar, planetary, and galactic studies #Supernova #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stab376
published in Monthly Notices of the Royal Astronomical Society 502(3), 4359-4376 (Oxford University Press) · 19 pages, 14 figures, 4 tables, accepted for publication in MNRAS
arxiv created 2021/02/07 · openalex publication_date 2021/02/09 · arxiv updated 2021/02/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT Understanding the evolution of the N/O ratio in the interstellar medium (ISM) of galaxies is essential if we are to complete our picture of the chemical evolution of galaxies at high redshift, since most observational calibrations of O/H implicitly depend upon the intrinsic N/O ratio. The observed N/O ratio, however, shows large scatter at low O/H, and is strongly dependent on galactic environment. We show that several heretofore unexplained features of the N/O distribution at low O/H can be explained by the N seen in metal-poor galaxies being mostly primary nitrogen that is returned to the ISM via pre-supernova winds from rapidly rotating massive stars (M ≳ 10 M⊙, v/vcrit ≳ 0.4). This mechanism naturally produces the observed N/O plateau at low O/H. We show that the large scatter in N/O at low O/H also arises naturally from variations in star-formation efficiency. By contrast, models in which the N and O come primarily from supernovae provide a very poor fit to the observed abundance distribution. We propose that the peculiar abundance patterns we observe at low O/H are a signature that dwarf galaxies retain little of their SN ejecta, leaving them with abundance patterns typical of winds.