Journal Article

The association of GRB 060218 with a supernova and the evolution of the shock wave

Moretti, A., Kennea, J. A., Cusumano, G., Mason, K. O., Cominsky, L. R., Malesani, D., Page, K. L., Angelini, L., Wells, A. A., Zhang, B., Sakamoto, T., Brown, P., Cummings, J. R., Blustin, A. J., Mangano, V., White, N. E., Tagliaferri, G., Godet, O., Page, M., Waxman, E., Krimm, H., Barthelmy, S. D., O'Brien, P. T., Palmer, D. M., Valle, M. Della, Osborne, J. P., Campana, S., Romano, P., Dai, Z. G., Immler, S., Boyd, P. T., Chincarini, G., Burrows, D. N., Nousek, J. A., Marshall, F. E., Mészáros, P., Giommi, P., Gehrels, N., Roming, P. W. A.

2006

Overview

X-Rated Supernova A link between long γ-ray bursts (GRBs) and supernovae has been established, but whether there is a similar relationship between the weaker and softer X-ray flashes and supernovae is unclear. GRB/XRF 060218, spotted by the Swift satellite on 18 February this year, may supply that missing link. In the first of four papers on this novel burster, Campana et al . report the sighting of the X-ray signature of a shock break-out, possible evidence of a supernova in progress. Pian et al . report the optical discovery of a type Ic supernova 2006aj associated with GRB/XRF 060218. Soderberg et al . report radio and X-ray observations that show that XRF 060218 is 100 times less energetic than, but of a type that is ten times more common than cosmological GRBs. Mazzali et al . modelled the spectra and light curve of SN 2006aj to show that it had a much smaller explosion energy and ejected much less mass than other GRB-supernovae, suggesting that it was produced by a star with a mass was only about 20 times that of the Sun, leaving behind a neutron star, rather than a black hole. Observations of the close gamma-ray burst GRB 060218 and its connection to supernova SN 2006aj reveal the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the GRB progenitor. These observation catch a supernova in the act of exploding. Although the link between long γ-ray bursts (GRBs) and supernovae has been established 1 , 2 , 3 , 4 , hitherto there have been no observations of the beginning of a supernova explosion and its intimate link to a GRB. In particular, we do not know how the jet that defines a γ-ray burst emerges from the star's surface, nor how a GRB progenitor explodes. Here we report observations of the relatively nearby GRB 060218 (ref. 5 ) and its connection to supernova SN 2006aj (ref. 6 ). In addition to the classical non-thermal emission, GRB 060218 shows a thermal component in its X-ray spectrum, which cools and shifts into the optical/ultraviolet band as time passes. We interpret these features as arising from the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the progenitor 7 . We have caught a supernova in the act of exploding, directly observing the shock break-out, which indicates that the GRB progenitor was a Wolf–Rayet star.

• Publisher: Nature Publishing Group UK,Nature Publishing,Nature Publishing Group
• Subject: Astronomy / Astrophysics / Band spectra / Bursts / Cosmology / Earth, ocean, space / Emissions / Evolution / Exact sciences and technology / Explosions / Gamma rays / Gamma-ray sources ; gamma-ray bursts / Humanities and Social Sciences / Late stages of stellar evolution (including black holes) / letter / Links / multidisciplinary / Science / Science (multidisciplinary) / Shells / Shock waves / Stars / Stellar systems. Galactic and extragalactic objects and systems. The universe / Supernovae / Supernovas / Unidentified sources and radiation outside the solar system / Wind / X-rays