A surge of light at the birth of a supernova

BERSTEN, M.C; FOLATELLI, G.; GARCÍA, F.; S. VANDYK; BENVENUTO, O.G.; ORELLANA, M.; OTROS AUTORES

NATURE

NATURE PUBLISHING GROUP

Lugar: Londres; Año: 2018 vol. 554 p. 497 - 499

0028-0836

Understanding the explosive end of massive stars is vital for astrophysics. One key subject is the early emission of the resulting supernova (SN), which carries unique signatures of the progenitor envelope structure, and thereby of its mass-loss history soon before the explosion. A sharp emission peak is expected during the first minutes to hours of the SN owing to the emergence of the shock wave through the stellar surface, the "shock breakout" (SBO). Given its astrophysical relevance, large efforts have been dedicated in recent years to discovering SNe during such an elusive phase. The few existing claims, based on serendipitous detections, are subject to ambiguous interpretations. Here we report the optical detection of an SBO signal seen in a normal Type IIb supernova (SN 2016gkg) by amateur astronomer Victor Buso. Based on our numerical modelling, the initial rise, with a rate of over 40 mag/day, can be attributed only to the SBO phase. Most importantly, we present a self-consistent model that is able to reproduce the SN light curve through three distinct phases: the shock emergence, the post-shock cooling, and the radioactivity-dominated phase. We obtain a thorough picture of the SN progenitor by independently analysing the existing pre-explosion images of the SN site in light of our interacting-binary-evolution models. Future observations may bring about more SBO detections; thus, the case of SN 2016gkg can serve as a reference in the interpretation of this signal in terms of the explosion and progenitor properties.