Year: 2026
Type: preprint
Abstract: 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.
Source: arXiv (Cornell University)
Authors: Pessi, P. J., Barmentloo, S., Wyrzykowski, Ł., Schulze, S., Sollerman, J., Gangopadhyay, A., Mikołajczyk, P. J., Rose, S., Kotysz, K., Fremling, C., Jerkstrand, A., Lunnan, R., Yan, L., Fransson, C., Wise, J. L., Dubey, M., Misra, K., Cotter, A. P., Athanasopoulos, D., Bochenek, A., Bronikowski, M., Burgaz, U., Burzynski, W., Carrasco, J. M., Concepcion, E., Galdies, C., Gillan, A. F., Gkini, A., Gkiokas, E., Głowacki, E., Hambsch, F-J., Japelj, J., Karaman, N., King, P., Kurowski, S., Liu, C., Maskoliunas, M., McGrath, Z., Mihelčič, M., Nikolajuk, M., Ogloza, W., Pakštienė, E., Pylypenko, U., Pucek, A., Rehemtulla, N., Rich, R. M., Simon, A. O., Singh, A., Skoglund, C., Stonkute, E., Stsefanenka, Y., Szober, P., Tsalapatas, K., van Baal, B. F. A., Ventura, C., Vrontaki, K., Wozniak, A., Zdanavicius, J., Zola, S., Bellm, E. C., Jaimes, J. Castaneda, Graham, M. J., Helou, G., Masci, F. J., Purdum, J. N., Riddle, R.
Institutions: National Centre for Nuclear Research, Stockholm University, AlbaNova, Weizmann Institute of Science, University of Wrocław, California Institute of Technology, University of Warsaw, Aryabhatta Research Institute of Observational Sciences, Liverpool John Moores University, University of Nova Gorica, Trinity College Dublin, University of Białystok, University of Malta, National Observatory of Athens, Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, Adıyaman University, University of California, Los Angeles, Jagiellonian University, Vilnius University, University of Turku, Taras Shevchenko National University of Kyiv, Adam Mickiewicz University in Poznań, Astronomical Observatory of Rome, National Institute for Astrophysics, University of Zielona Góra, University of Washington, Infrared Processing and Analysis Center
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, University of Pennsylvania, Ohio State University, California Institute of Technology, University of Chicago, University of Portsmouth, National Energy Research Scientific Computing Center, University College London, European Commission, University of Sussex, Deutsche Forschungsgemeinschaft, Chinese Academy of Sciences, Ministerstwo Edukacji i Nauki, Financiadora de Estudos e Projetos, University of Illinois at Urbana-Champaign, Office of Science, Jet Propulsion Laboratory, HORIZON EUROPE Framework Programme, Science and Technology Facilities Council, Division of Astronomical Sciences, High Energy Physics, Integrated Electronics Engineering Center, Binghamton University, Argonne National Laboratory, Fermilab, Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory
Awards: G1039895795, G1265337469, G1313983767, G1800429324, G1813527838, G272672434, Exploring & Exploiting the Dynamic Optical Sky, G2994122026, G3204085874, ZWICKY TRANSIENT FACILITY, G387521742, G3880645893, G4221417635, G4392917094, G4508498098, G4930006217, G498139845, Opticon RadioNet Pilot, Enabling Synergistic Science between the Rubin Observatory and the Zwicky Transient Facility, Astrophysics Center for Multimessenger studies in Europe, G6876926712, Management and Operations of the National Optical Astronomy Observatory, G7406122311, G7861570460, G823181903, G8292014801, G969889393, G988696487
OpenAlex ID: W7212032113
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