Contribution of very massive stars to the sulfur abundance in star-forming galaxies: Role of pair-instability supernovae

• Published in: Astronomy and astrophysics (Berlin) 2024-05, Vol.685, p.A81
• Main Authors: Goswami, S., Vilchez, J. M., Pérez-Díaz, B., Silva, L., Bressan, A., Pérez-Montero, E.
• Format: Article
• Language: English
• Subjects: Abundance; Chemical evolution; Ejecta; Galaxies; Initial mass function; Massive stars; Metallicity; Oxygen enrichment; Star & galaxy formation; Star formation; Stars & galaxies; Sulfur; Supernovae
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202348231

Context. Recent work presented increasing evidence of high non-constant S/O abundance ratios observed in star-forming metal-poor galaxies that deviated from the constant canonical S/O across a wide range of O/H abundances. Similar peculiarly high Fe/O ratios have also recently been detected. Aims. We investigate whether these high S/O ratios at low metallicities could be explained when the process of pair-instability supernovae (PISN) in chemical modelling is included, through which a similar behaviour of the Fe/O ratios was reproduced successfully. Methods. We used chemical evolution models that considered the stages of PISN in the previously published yields and adopted a suitable initial mass function (IMF) to characterize this evolutionary stage appropriately. Results. The peculiarly high values and the behaviour of the observed S/O versus O/H relation can be reproduced when the ejecta of very massive stars that go through the process of PISN are taken into account. Additionally, a bimodal top-heavy IMF and an initial strong burst of star formation are required to reach the reported high S/O values. Conclusions. We show that the role of very massive stars going through the process of PISN should be taken into account to explain the chemical enrichment of sulphur and oxygen in metal-poor star-forming regions.