Impact of stellar winds on the pair-instability supernova rate

¹ Physics and Astronomy Department Galileo Galilei, University of Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
² Gran Sasso Science Institute (GSSI), Viale Francesco Crispi 7, 67100 L’Aquila, Italy
³ INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi, Italy
⁴ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁵ Universität Heidelberg, Zentrum für Astronomie (ZAH), Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany
⁶ Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Heidelberg, Germany
⁷ INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova, Italy
⁸ Departament de Física Quàntica i Astrofísica, Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
⁹ SISSA, via Bonomea 365, 34136 Trieste, Italy
¹⁰ National Institute for Nuclear Physics – INFN, Sezione di Trieste, 34127 Trieste, Italy
¹¹ Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monteporzio Catone, Italy

^★ Corresponding authors: filippo.simonato@gssi.it; sttorniamenti@mpia.de; mapelli@uni-heidelberg.de

Received: 12 May 2025
Accepted: 2 September 2025

Abstract

Very massive stars (VMSs, M_★ ≥ 100 M_⊙) play a crucial role in several astrophysical processes. At low metallicity, they might collapse directly into black holes or end their lives as pair-instability supernovae. Recent observational results set an upper limit of 0.7 yr⁻¹ Gpc⁻³ on the rate density of pair-instability supernovae in the nearby Universe. However, most theoretical models predict rates exceeding this limit. In this work, we computed new VMS tracks with the MESA code and used them to analyze the evolution of the (pulsational) pair-instability supernova rate density across cosmic time. We show that stellar-wind models accounting for the transition between optically thin and thick winds yield a pair-instability supernova rate of ℛ_PISN ~ 0.1 Gpc⁻³ yr⁻¹ at redshift ɀ ~ 0, which is about two orders of magnitude lower than our previous models. We find that the main contribution to the pair-instability supernova rate comes from stars with metallicities of Z ~ 0.001 − 0.002. Stars with higher metallicities cannot enter the pair-instability supernova regime, even if their zero-age main-sequence mass is up to 500 M_⊙. The main reason is that VMSs enter the regime for optically thick winds during the main sequence at metallicities as low as Z ~ 4 × 10⁻⁴. This enhances the mass-loss rate, quenching the growth of the He core and thus preventing the onset of pair-instability in later evolutionary stages. This result highlights the critical role of mass loss in shaping the final fate of very massive stars and the rate of pair-instability supernovae.