IPTF 16asu: A Luminous, Rapidly Evolving, and High-velocity Supernova

L. Whitesides, R. Lunnan, M. M. Kasliwal, D. A. Perley, A. Corsi, S. B. Cenko, N. Blagorodnova, Y. Cao, D. O. Cook, G. B. Doran, D. D. Frederiks, C. Fremling, K. Hurley, E. Karamehmetoglu, S. R. Kulkarni, G. Leloudas, F. Masci, P. E. Nugent, A. Ritter, A. RubinV. Savchenko, J. Sollerman, D. S. Svinkin, F. Taddia, P. Vreeswijk, P. Wozniak

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Wide-field surveys are discovering a growing number of rare transients whose physical origin is not yet well understood. Here we present optical and UV data and analysis of intermediate Palomar Transient Factory (iPTF) 16asu, a luminous, rapidly evolving, high-velocity, stripped-envelope supernova (SN). With a rest-frame rise time of just four days and a peak absolute magnitude of Mg = -20.4 mag, the light curve of iPTF 16asu is faster and more luminous than that of previous rapid transients. The spectra of iPTF 16asu show a featureless blue continuum near peak that develops into an SN Ic-BL spectrum on the decline. We show that while the late-time light curve could plausibly be powered by 56Ni decay, the early emission requires a different energy source. Nondetections in the X-ray and radio strongly constrain the energy coupled to relativistic ejecta to be at most comparable to the class of low-luminosity gamma-ray bursts (GRBs). We suggest that the early emission may have been powered by either a rapidly spinning-down magnetar or by shock breakout in an extended envelope of a very energetic explosion. In either scenario a central engine is required, making iPTF 16asu an intriguing transition object between superluminous SNe, SNe Ic-BL, and low-luminosity GRBs.

Original languageEnglish
Article number107
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 20 2017


  • gamma-ray burst: general
  • shock waves
  • stars: magnetars
  • supernovae: general
  • supernovae: individual (iPTF 16asu)


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