A1 Refereed original research article in a scientific journal
Slowly fading super-luminous supernovae that are not pair-instability explosions
Authors: Nicholl M, Smartt SJ, Jerkstrand A, Inserra C, McCrum M, Kotak R, Fraser M, Wright D, Chen TW, Smith K, Young DR, Sim SA, Valenti S, Howell DA, Bresolin F, Kudritzki RP, Tonry JL, Huber ME, Rest A, Pastorello A, Tomasella L, Cappellaro E, Benetti S, Mattila S, Kankare E, Kangas T, Leloudas G, Sollerman J, Taddia F, Berger E, Chornock R, Narayan G, Stubbs CW, Foley RJ, Lunnan R, Soderberg A, Sanders N, Milisavljevic D, Margutti R, Kirshner RP, Elias-Rosa N, Morales-Garoffolo A, Taubenberger S, Botticella MT, Gezari S, Urata Y, Rodney S, Riess AG, Scolnic D, Wood-Vasey WM, Burgett WS, Chambers K, Flewelling HA, Magnier EA, Kaiser N, Metcalfe N, Morgan J, Price PA, Sweeney W, Waters C
Publisher: NATURE PUBLISHING GROUP
Publication year: 2013
Journal: Nature
Journal name in source: NATURE
Journal acronym: NATURE
Number in series: 7471
Volume: 502
Issue: 7471
First page : 346
Last page: 349
Number of pages: 4
ISSN: 0028-0836
DOI: https://doi.org/10.1038/nature12569(external)
Super-luminous supernovae(1-4) 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(5,6). 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 Ni-56 are synthesized; this isotope decays to Fe-56 via Co-56, powering bright light curves(7,8). Such massive progenitors are expected to have formed from metal-poor gas in the early Universe(9). 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(1,10). 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(2,11,12), which are not powered by radio-activity. Modelling our observations with 10-16 solar masses of magnetar-energized(13,14) 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 x 10(-6) times that of the core-collapse rate.