We present late-time (δt > 3000 days) optical (Keck), X-ray (Chandra and the Nuclear Spectroscopic Telescope Array), and radio (the Very Large Area, the Atacama Large Millimeter/submillimeter Array, and the Upgraded Giant Metrewave Radio Telescope) observations of the Type Ic-BL (SN Ic-BL) SN 2012ap. Previous studies of this supernova (SN) have suggested that it stands out as a key example of a weak engine-driven explosion due to the lack of gamma-ray burst (GRB) detection and mildly relativistic ejecta. Recently, radio sky surveys revealed the rebrightening of the radio emission from this SN, highlighting the possibilities of a density enhancement at large radii or the existence of an off-axis relativistic jet. While the late-time optical spectra do not exhibit the broad emission lines seen in other interacting supernovae (SNe), our analysis of the broadband radio and X-ray emission implies that both scenarios are plausible. If a density enhancement is responsible for the radio rebrightening, it has to result from a change in the mass-loss rate and/or wind velocity, possibly due to the transition of the progenitor from a red supergiant to a Wolf–Rayet star. If the late-time radio component is a result of an off-axis relativistic jet, we find that an energetic narrow jet viewed at θobs ≥ 80° is needed. In this scenario, SN 2012ap is not a result of a weak engine-driven explosion, and instead, it is similar to other GRBs. However, radio rebrightenings of SN Ic-BL are not enough on their own to determine the existence of off-axis jets, and our planned Very Long Baseline Array observation will help reveal the true nature of this SN.
- A 14-yr-old Mystery: The Peculiar Case of the Engine-driven SN 2012ap
- Itai Sfaradi - University of California SystemRaffaella Margutti - University of California SystemRyan Chornock - University of California SystemNayana A. JEli Wiston - University of California SystemFabio De Colle - Universidad Nacional Autónoma de MéxicoTracy E Clarke - United States Naval Research LaboratoryWendy M Peters - United States Naval Research LaboratoryPaz Beniamini - Open University of IsraelWenbin Lu - University of California SystemRodolfo Barniol DuranMichael Bietenholz - York UniversityCollin T Christy - University of ArizonaDeanne L Coppejans - University of WarwickMaria R Drout - University of TorontoDina Ibrahimzade - University of California SystemMichał J Michałowski - Adam Mickiewicz University in PoznańDan Milisavljevic - Purdue University West LafayetteConor M. B Omand - Liverpool John Moores UniversityYihan WangKate D Alexander - University of ArizonaCarles Badenes - University of PittsburghJoe Bright - University of OxfordJonathan Granot - Open University of IsraelErica Hammerstein - University of California SystemW. V Jacobson-Galán - California Institute of TechnologyNatalie LeBaron - University of California SystemKohta Murase - Instituto de Física TeóricaGitika Rameshan - Indian Institute of AstrophysicsHuei Sears - Rutgers, The State University of New JerseyMichael Stroh - National Radio Astronomy ObservatoryGiacomo Terreran - Adler Planetarium
- Physics and Astronomy Department
- IOP Publishing; Bristol
- 07/01/2026
- National Science Foundation (NSF) U.S. Naval Research Laboratory Sustainment Restoration and Maintenance fund ALMA: 2021.1.00099 National Aeronautics and Space Administration (NASA): GO2-23052X, GO2-23039X, NAS8-03060 Chandra X-ray Observatory National Aeronautics and Space Administration W. M. Keck Foundation
The NRAO is a facility of the National Science Foundation (NSF) operated under cooperative agreement by Associated Universities, Inc. We thank the NRAO for carrying out the Karl G. Jansky VLA. Construction and installation of VLITE was supported by the U.S. Naval Research Laboratory Sustainment Restoration and Maintenance fund. We thank the staff of the GMRT who made these observations possible. The GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2021.1.00099.S ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSTC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Space Science Data Center (SSDC, Italy) and the California Institute of Technology (Caltech, USA). Support for this work was provided by the National Aeronautics and Space Administration (NASA) through Chandra Award Numbers GO2-23052X and GO2-23039X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. This research employs a list of Chandra datasets, obtained by the Chandra X-ray Observatory, contained in DOI:10.25574/cdc.604. Basic research in radio astronomy at the U.S. Naval Research Laboratory is supported by 6.1 Base funding. Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c)3 nonprofit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
- 99258329773801671; https://hdl.handle.net/20.500.12741/rep:14171; https://doi.org/10.3847/2041-8213/ae796d
- English
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