The Type II supernova SN 2020jfo in M 61, implications for progenitor system, and explosion dynamics

Creators: Sollerman, J.; Yang, S.; Schulze, S.; Strotjohann, N. L.; Jerkstrand, A.; Van Dyk, S. D.; Kool, E. C.; Barbarino, C.; Brink, T. G.; Bruch, R.; De, K.; Filippenko, A. V.; Fremling, C.; Patra, K. C.; Perley, D.; Yan, L.; Yang, Y.; Andreoni, I.; Campbell, R.; Coughlin, M.; Kasliwal, M.; Kim, Y.-L.; Rigault, M.; Shin, K.; Tzanidakis, A.; Ashley, M. C. B.; Moore, A. M.; Travouillon, T.

Abstract

We present the discovery and extensive follow-up observations of SN 2020jfo, a Type IIP supernova (SN) in the nearby (14.5 Mpc) galaxy M 61. Optical light curves (LCs) and spectra from the Zwicky Transient Facility (ZTF), complemented with data from Swift/UVOT and near-infrared photometry is presented. These were used to model the 350-day duration bolometric light curve, which exhibits a relatively short (∼65 days) plateau. This implies a moderate ejecta mass (∼5 M_⊙) at the time of explosion, whereas the deduced amount of ejected radioactive nickel is ∼0.025 M_⊙. An extensive series of spectroscopy is presented, including spectropolarimetric observations. The nebular spectra are dominated by Hα, but also reveal emission lines from oxygen and calcium. Comparisons to synthetic nebular spectra indicate an initial progenitor mass of ∼12 M_⊙. We also note the presence of stable nickel in the nebular spectrum, and SN 2020jfo joins a small group of SNe that have inferred super-solar Ni/Fe ratios. Several years of prediscovery data were examined, but no signs of precursor activity were found. Pre-explosion Hubble Space Telescope imaging reveals a probable progenitor star, detected only in the reddest band (M_(F814W) ≈ −5.8) and it is fainter than expected for stars in the 10−15 M_⊙ range. There is thus some tension between the LC analysis, the nebular spectral modeling, and the pre-explosion imaging. To compare and contrast, we present two additional core-collapse SNe monitored by the ZTF, which also have nebular Hα-dominated spectra. This illustrates how the absence or presence of an interaction with circumstellar material (CSM) affect both the LCs and in particular the nebular spectra. Type II SN 2020amv has a LC powered by CSM interaction, in particular after ∼40 days when the LC is bumpy and slowly evolving. The late-time spectra show strong Hα emission with a structure suggesting emission from a thin, dense shell. The evolution of the complex three-horn line profile is reminiscent of that observed for SN 1998S. Finally, SN 2020jfv has a poorly constrained early-time LC, but it is of interest because of the transition from a hydrogen-poor Type IIb to a Type IIn, where the nebular spectrum after the light-curve rebrightening is dominated by Hα, although with an intermediate line width.

Additional Information

© ESO 2021. Received: 24 May 2021 Accepted: 8 September 2021. We thank the staffs of the various observatories where data were obtained for their excellent assistance. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the US National Science Foundation (NSF) under grant AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. ZTF-II is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW. The SED Machine is based upon work supported by the NSF under grant AST-1106171. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant #12540303 (PI M. Graham). This work was supported by the GROWTH project funded by the NSF under PIRE grant 1545949. The Oskar Klein Centre was funded by the Swedish Research Council. Gravitational Radiation and Electromagnetic Astrophysical Transients (GREAT) is funded by the Swedish Research council (VR) under Dnr 2016-06012. ECK is further supported by the Wenner-Gren Foundations. Much support to OKC involvement in ZTF was provided by the Knut and Alice Wallenberg foundation. Partially based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. Some of the data presented here were obtained with ALFOSC. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Support for program GO-16179 was provided by NASA through a grant from STScI. We thank T. de Jaeger, O. D. Fox, P. Kelly, N. Smith, S. Vasylyev, and W. Zheng for their assistance with this program. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA; 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 indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. A major upgrade of the Kast spectrograph on the Shane 3 m telescope at Lick Observatory was made possible through generous gifts from the Heising-Simons Foundation as well as William and Marina Kast. Research at Lick Observatory is partially supported by a generous gift from Google. Palomar Gattini-IR (PGIR) is generously funded by Caltech, the Australian National University, the Mt. Cuba Foundation, the Heising-Simons Foundation, and the Binational Science Foundation. PGIR is a collaborative project among Caltech, the Australian National University, University of New South Wales, Columbia University, and the Weizmann Institute of Science. Y.-L. K. has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant 759194 – USNAC). M. C. acknowledges support from the NSF through grant PHY-2010970. Funding for A. V. F.'s research group at U. C. Berkeley was provided by the Christopher R. Redlich Fund and the Miller Institute for Basic Research in Science (where A. V. F. is a Senior Miller Fellow). This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112, HST grant GO-15889 from STScI, and STFC grants ST/T000198/1 and ST/S006109/1. A. J. acknowledges funding from the European Research Council (ERC) through Starting Grant 803189. This work has made use of data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) project. The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; by products of the asteroid search include images and catalogues from the survey area. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, STScI, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. Full Tables 2–4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/655/A105

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