Astrochemistry

Can Pre-supernova Winds From Massive Stars Enrich The Interstellar Medium With Nitrogen At High Redshift?

By Keith Cowing

Status Report

astro-ph.GA

January 21, 2023

Filed under astro-ph.GA, interstellar medium, metallicity, Nitrogen, Supernova

Can Pre-supernova Winds From Massive Stars Enrich The Interstellar Medium With Nitrogen At High Redshift? — Adapted from Figure 8 of Roy et al. (2021): log(N/O) vs. log(O/H) from our models (coloured data points) and observations (black data points). Top panel: Models of galaxies that retain only the low-velocity pre-SN wind yields, Bottom panel: galaxies that retain both SNe ejecta and pre-SN winds. Black filled points (representing stellar yields) show the observations of several authors: Israelian et al. (2004) (I04, circles), Spite et al. (2005) (S05, pentagons), Nieva & Przybilla (2012) (NP12, squares), and open circles represent the HII regions (IT99, Izotov et al. (1999)). The orange dashed lines show the primary and secondary N production channels as proposed by Dopita et al. (2016). The red star represents the solar value. The dashed blue and brown boxes divide the N/O versus O/H phase space into two regimes based on our theoretical predictions that metal-poor dwarfs (blue box) retain only wind ejecta, leading to a low N/O ratio with large scatter characteristic of wind yields, while metal-rich massive galaxies (brown box) retain both wind and SN ejecta, leading to a higher N/O ratio characteristic of SNe. Coloured points represent theoretical predictions for different initial metallicity [Fe/H] and star formation efficiency ∗ as indicated by the figure legend. For each point, the horizontal bar corresponds to the scenario where a galaxy accretes an additional fraction of primordial (p) hydrogen and helium followed by the star-formation event. Our assumed range of p are log p = −0.5−0.5. Note that, we omit the [Fe/H] = −4 case for SN yields because our SN yield tables only go down to [Fe/H] = −3 as adopted from Limongi & Chieffi (2018).

Understanding the nucleosynthetic origin of nitrogen and the evolution of the N/O ratio in the interstellar medium is crucial for a comprehensive picture of galaxy chemical evolution at high-redshift because most observational metallicity (O/H) estimates are implicitly dependent on the N/O ratio.

The observed N/O at high-redshift shows an overall constancy with O/H, albeit with a large scatter. We show that these heretofore unexplained features can be explained by the pre-supernova wind yields from rotating massive stars (M≳10M⊙, v/vcrit≳0.4).

Our models naturally produce the observed N/O plateau, as well as the scatter at low O/H. We find the scatter to arise from varying star formation efficiency. However, the models that have supernovae dominated yields produce a poor fit to the observed N/O at low O/H.

This peculiar abundance pattern at low O/H suggests that dwarf galaxies are most likely to be devoid of SNe yields and are primarily enriched by pre-supernova wind abundances.

Arpita Roy, Mark R. Krumholz, Michael A. Dopita, Ralph S. Sutherland, Lisa J. Kewley, Alexander Heger

Comments: 6 pages, 1 figure, published in Proceedings of the International Astronomical Union No. 366, 2022 titled “The Origin of Outflows in Evolved Stars”
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Cite as: arXiv:2212.05103 [astro-ph.GA] (or arXiv:2212.05103v1 [astro-ph.GA] for this version)
Journal reference: Proceedings of the International Astronomical Union, 16(S366), 33-38, 2022
Related DOI:
https://doi.org/10.1017/S1743921322000722
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Submission history
From: Arpita Roy
[v1] Fri, 9 Dec 2022 20:06:23 UTC (175 KB)
https://arxiv.org/abs/2212.05103
Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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