A missing-link in the supernova-GRB connection: The case of SN 2012ap

Sayan Chakraborti, Alicia Soderberg, Laura Chomiuk, Atish Kamble, Naveen Yadav, Alak Ray, Kevin Hurley, Raffaella Margutti, Dan Milisavljevic, Michael Bietenholz, Andreas Brunthaler, Giuliano Pignata, Elena Pian, Paolo Mazzali, Claes Fransson, Norbert Bartel, Mario Hamuy, Emily Levesque, Andrew Macfadyen, Jason DittmannMiriam Krauss, M. S. Briggs, V. Connaughton, K. Yamaoka, T. Takahashi, M. Ohno, Y. Fukazawa, M. Tashiro, Y. Terada, T. Murakami, J. Goldsten, S. Barthelmy, N. Gehrels, J. Cummings, H. Krimm, D. Palmer, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin, T. Cline, I. G. Mitrofanov, D. Golovin, M. L. Litvak, A. B. Sanin, W. Boynton, C. Fellows, K. Harshman, H. Enos, A. Von Kienlin, A. Rau, X. Zhang, V. Savchenko

    Research output: Contribution to journalArticlepeer-review


    Gamma-ray bursts (GRBs) are characterized by ultra-relativistic outflows, while supernovae are generally characterized by non-relativistic ejecta. GRB afterglows decelerate rapidly, usually within days, because their low-mass ejecta rapidly sweep up a comparatively larger mass of circumstellar material. However, supernovae with heavy ejecta can be in nearly free expansion for centuries. Supernovae were thought to have non-relativistic outflows except for a few relativistic ones accompanied by GRBs. This clear division was blurred by SN 2009bb, the first supernova with a relativistic outflow without an observed GRB. However, the ejecta from SN 2009bb was baryon loaded and in nearly free expansion for a year, unlike GRBs. We report the first supernova discovered without a GRB but with rapidly decelerating mildly relativistic ejecta, SN 2012ap. We discovered a bright and rapidly evolving radio counterpart driven by the circumstellar interaction of the relativistic ejecta. However, we did not find any coincident GRB with an isotropic fluence of more than one-sixth of the fluence from GRB 980425. This shows for the first time that central engines in SNe Ic, even without an observed GRB, can produce both relativistic and rapidly decelerating outflows like GRBs.

    Original languageEnglish (US)
    Article number187
    JournalAstrophysical Journal
    Issue number2
    StatePublished - Jun 1 2015


    • gamma-ray burst: general
    • radiation mechanisms: non-thermal
    • shock waves
    • supernovae: individual (SN 2012ap)
    • techniques: interferometric

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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