Slowly fading super-luminous supernovae that are not pair-instability explosions

Research output: Contribution to journalArticle

Authors

  • S. J. Smartt
  • A. Jerkstrand
  • C. Inserra
  • M. McCrum
  • R. Kotak
  • M. Fraser
  • D. Wright
  • T. -W. Chen
  • K. Smith
  • D. R. Young
  • S. A. Sim
  • S. Valenti
  • D. A. Howell
  • F. Bresolin
  • R. P. Kudritzki
  • J. L. Tonry
  • M. E. Huber
  • A. Rest
  • A. Pastorello
  • L. Tomasella
  • E. Cappellaro
  • S. Benetti
  • S. Mattila
  • E. Kankare
  • T. Kangas
  • G. Leloudas
  • J. Sollerman
  • F. Taddia
  • E. Berger
  • R. Chornock
  • G. Narayan
  • C. W. Stubbs
  • R. J. Foley
  • R. Lunnan
  • A. Soderberg
  • N. Sanders
  • D. Milisavljevic
  • R. Margutti
  • R. P. Kirshner
  • N. Elias-Rosa
  • A. Morales-Garoffolo
  • S. Taubenberger
  • M. T. Botticella
  • S. Gezari
  • Y. Urata
  • S. Rodney
  • A. G. Riess
  • D. Scolnic
  • W. M. Wood-Vasey
  • W. S. Burgett
  • K. Chambers
  • H. A. Flewelling
  • E. A. Magnier
  • N. Kaiser
  • N. Metcalfe
  • J. Morgan
  • P. A. Price
  • W. Sweeney
  • C. Waters

Colleges, School and Institutes

Abstract

Super-luminous supernovae that radiate more than 1044 ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of `pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of 56Ni are synthesized; this isotope decays to 56Fe via 56Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10-6 times that of the core-collapse rate....

Details

Original languageUndefined/Unknown
JournalNature
Publication statusPublished - Oct 2013