A very luminous magnetar-powered supernova associated with an ultra-long γ-ray burst
A new class of ultra-long-duration (more than 10,000 seconds) γ-ray bursts has recently been suggested. They may originate in the explosion of stars with much larger radii than those producing normal long-duration γ-ray bursts or in the tidal disruption of a star. No clear supernova has yet been associated with an ultra-long-duration γ-ray burst. Here we report that a supernova (SN 2011kl) was associated with the ultra-long-duration γ-ray burst GRB 111209A, at a redshift z of 0.677. This supernova is more than three times more luminous than type Ic supernovae associated with long-duration γ-ray bursts, and its spectrum is distinctly different. The slope of the continuum resembles those of super-luminous supernovae, but extends further down into the rest-frame ultraviolet implying a low metal content. The light curve evolves much more rapidly than those of super-luminous supernovae. This combination of high luminosity and low metal-line opacity cannot be reconciled with typical type Ic supernovae, but can be reproduced by a model where extra energy is injected by a strongly magnetized neutron star (a magnetar), which has also been proposed as the explanation for super-luminous supernovae.
Greiner, J., Mazzali, P., Kann, D., Krühler, T., Pian, E., Prentice, S., Olivares E., F., Rossi, A., Klose, S., Taubenberger, S., Knust, F., Afonso, P., Ashall, C., Bolmer, J., Delvaux, C., Diehl, R., Elliott, J., Filgas, R., Fynbo, J., Graham, J., Guelbenzu, A., Kobayashi, S., Leloudas, G., Savaglio, S., Schady, P., Schmidl, S., Schweyer, T., Sudilovsky, V., Tanga, M., Updike, A., Van Eerten, H., & Varela, K. (2015). A very luminous magnetar-powered supernova associated with an ultra-long γ-ray burst. Nature, 523 (7559), 189-192. https://doi.org/10.1038/nature14579