SN 2024afyu interpreted as a Pair Instability Supernova

@misc{pessi20262024afyu,
  title = {{SN 2024afyu interpreted as a Pair Instability Supernova}},
  author = {P. J. Pessi and S. Barmentloo and Ł. Wyrzykowski and S. Schulze and J. Sollerman and A. Gangopadhyay and P. J. Mikołajczyk and S. Rose and K. Kotysz and C. Fremling and A. Jerkstrand and R. Lunnan and L. Yan and C. Fransson and J. L. Wise and M. Dubey and K. Misra and A. P. Cotter and D. Athanasopoulos and A. Bochenek and M. Bronikowski and U. Burgaz and W. Burzynski and J. M. Carrasco and E. Concepcion and C. Galdies and A. F. Gillan and A. Gkini and E. Gkiokas and E. Głowacki and F-J. Hambsch and J. Japelj and N. Karaman and P. King and S. Kurowski and C. Liu and M. Maskoliunas and Z. McGrath and M. Mihelčič and M. Nikolajuk and W. Ogloza and E. Pakštienė and U. Pylypenko and A. Pucek and N. Rehemtulla and R. M. Rich and A. O. Simon and A. Singh and C. Skoglund and E. Stonkute and Y. Stsefanenka and P. Szober and K. Tsalapatas and B. F. A. van Baal and C. Ventura and K. Vrontaki and A. Wozniak and J. Zdanavicius and S. Zola and E. C. Bellm},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.07931},
  eprint = {2609.07931},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.07931},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - SN 2024afyu interpreted as a Pair Instability Supernova
AU  - P. J. Pessi
AU  - S. Barmentloo
AU  - Ł. Wyrzykowski
AU  - S. Schulze
AU  - J. Sollerman
AU  - A. Gangopadhyay
AU  - P. J. Mikołajczyk
AU  - S. Rose
AU  - K. Kotysz
AU  - C. Fremling
AU  - A. Jerkstrand
AU  - R. Lunnan
AU  - L. Yan
AU  - C. Fransson
AU  - J. L. Wise
AU  - M. Dubey
AU  - K. Misra
AU  - A. P. Cotter
AU  - D. Athanasopoulos
AU  - A. Bochenek
AU  - M. Bronikowski
AU  - U. Burgaz
AU  - W. Burzynski
AU  - J. M. Carrasco
AU  - E. Concepcion
AU  - C. Galdies
AU  - A. F. Gillan
AU  - A. Gkini
AU  - E. Gkiokas
AU  - E. Głowacki
AU  - F-J. Hambsch
AU  - J. Japelj
AU  - N. Karaman
AU  - P. King
AU  - S. Kurowski
AU  - C. Liu
AU  - M. Maskoliunas
AU  - Z. McGrath
AU  - M. Mihelčič
AU  - M. Nikolajuk
AU  - W. Ogloza
AU  - E. Pakštienė
AU  - U. Pylypenko
AU  - A. Pucek
AU  - N. Rehemtulla
AU  - R. M. Rich
AU  - A. O. Simon
AU  - A. Singh
AU  - C. Skoglund
AU  - E. Stonkute
AU  - Y. Stsefanenka
AU  - P. Szober
AU  - K. Tsalapatas
AU  - B. F. A. van Baal
AU  - C. Ventura
AU  - K. Vrontaki
AU  - A. Wozniak
AU  - J. Zdanavicius
AU  - S. Zola
AU  - E. C. Bellm
PY  - 2026
DA  - 2026/09/07
PB  - arXiv
DO  - 10.48550/arxiv.2609.07931
UR  - https://arxiv.org/abs/2609.07931
AB  - Pair-instability supernovae (PISNe) are the predicted explosions of very massive stars triggered by electron-positron pair production. Numerous transients have been proposed as PISN candidates, yet none has provided unambiguous confirmation of this explosion mechanism. The predicted strengths of nebular emission lines offer a powerful means of testing the PISN scenario. We investigate the nature of SN 2024afyu, a nearby (z = 0.0085), long-lived (trise = 85 +- 11.7 days) SN with peculiar spectral evolution, with the aim of identifying its powering mechanism. We analyse multi-band photometry and optical and near-infrared spectroscopy from shortly after explosion to the nebular phase (around 500 days past peak). Besides early appearance of [Ca II] features, we identify a number of sulfur and silicon emission lines, for which we estimate electron temperatures and elemental masses. SN 2024afyu has an inferred 56Ni mass of around 0.4 to 1.0 solar masses and an inferred sulfur mass of the order of 3 solar masses, substantially larger than expected for conventional core-collapse explosions. SN 2024afyu is photometrically similar (although fainter, M_Peak(r) = -18.9 +- 0.04 mag) but spectroscopically distinct to other proposed PISNe. Yet, existing PISN models broadly reproduce several key characteristics, including the overall spectral appearance and broad photometric evolution. SN 2024afyu is a strong PISN candidate, since alternative scenarios would struggle to explain the combination of broad light curve, large intermediate-mass-element abundance, and general spectroscopic evolution. The discrepancies between the observations and currently available theoretical models highlight the need for new PISN calculations spanning a wider range of progenitor masses, metallicities, mixing prescriptions, and circumstellar environments.
ER  -