[1505.00777] Late-Time Photometry of Type Ia Supernova SN2012cg Reveals the Radioactive Decay of $^{57}$Co

[1505.00777] Late-Time Photometry of Type Ia Supernova SN2012cg Reveals the Radioactive Decay of $^{57}$Co:



"Seitenzahl et al. (2009) have predicted that ∼3 years after its explosion, the light we receive from a Type Ia supernova will come mostly from reprocessing of electrons and X-rays emitted by the radioactive decay chain 57Co → 57Fe, instead of positrons from the decay chain 56Co → 56Fe that dominates the supernova light at earlier times. Using the Hubble Space Telescope, we followed the light curve of the Type Ia supernova SN2012cg out to 1055 days after maximum light. Our measurements are consistent with the light curves predicted by the contribution of energy from the reprocessing of electrons and X-rays emitted by the decay of 57Co. This provides conclusive evidence that 57Co is produced in Type Ia supernova explosions. The ratio of luminosities produced by the decays of 57Co and 56Co, a strong constraint on any Type Ia supernova explosion model, is in the range (0.4 - 8.5)×10−3."



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