Discovery of the nearby long, soft GRB 100316D with an associated supernova
Sakamoto, T.; Covino, S.; D'Avanzo, P.; Campana, S.; Pian, E.; D'Elia, V.; Sollerman, J.; Goldoni, P.; Nugent, P. E.; Kouveliotou, C.; Kaper, L.; Fruchter, A. S.; Gehrels, N.; Fynbo, J. P. U.; O'Brien, P. T.; van der Horst, A. J.; Rowlinson, A.; Gorosabel, J.; Wiersema, K.; Osborne, J. P.; Page, K. L.; Burrows, D. N.; Levan, A. J.; Starling, R. L. C.; Bersier, D.; Oates, S. R.; Tanvir, N. R.; Malesani, D.; Vergani, S. D.; Barthelmy, S.; Cano, Z.; Curran, P. A.; de Pasquale, M.; Evans, P. A.; Flores, H.; Garnavich, P.; Hjorth, J.; Holland, S. T.; Hurkett, C. P.; Jakobsson, P.; Kamble, A. P.; Kuin, N. P. M.; Mazzali, P. A.; Stamatikos, M.; Thöne, C. C.; Woosley, S. E.
United Kingdom, United States, France, Italy, Sweden, Denmark, Spain, Iceland, Netherlands, Germany
Abstract
We report the Swift discovery of the nearby long, soft gamma-ray burst GRB 100316D, and the subsequent unveiling of its low-redshift host galaxy and associated supernova. We derive the redshift of the event to be z= 0.0591 ± 0.0001 and provide accurate astrometry for the gamma-ray burst (GRB) supernova (SN). We study the extremely unusual prompt emission with time-resolved γ-ray to X-ray spectroscopy and find that the spectrum is best modelled with a thermal component in addition to a synchrotron emission component with a low peak energy. The X-ray light curve has a remarkably shallow decay out to at least 800 s. The host is a bright, blue galaxy with a highly disturbed morphology and we use Gemini-South, Very Large Telescope and Hubble Space Telescope observations to measure some of the basic host galaxy properties. We compare and contrast the X-ray emission and host galaxy of GRB 100316D to a subsample of GRB-SNe. GRB 100316D is unlike the majority of GRB-SNe in its X-ray evolution, but resembles rather GRB 060218, and we find that these two events have remarkably similar high energy prompt emission properties. Comparison of the host galaxies of GRB-SNe demonstrates, however, that there is a great diversity in the environments in which GRB-SNe can be found. GRB 100316D is an important addition to the currently sparse sample of spectroscopically confirmed GRB-SNe, from which a better understanding of long GRB progenitors and the GRB-SN connection can be gleaned.