GRB110721A was observed by the Fermi Gamma-ray Space Telescope using its two instruments, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). The burst consisted of one major emission episode which lasted for similar to 24.5 s (in the GBM) and had a peak flux of (5.7 +/- 0.2) x 10(-5) erg s(-1) cm(-2). The time-resolved emission spectrum is best modeled with a combination of a Band function and a blackbody spectrum. The peak energy of the Band component was initially 15 +/- 2 MeV, which is the highest value ever detected in a GRB. This measurement was made possible by combining GBM/BGO data with LAT Low Energy events to achieve continuous 10-100 MeV coverage. The peak energy later decreased as a power law in time with an index of -1.89 +/- 0.10. The temperature of the blackbody component also decreased, starting from similar to 80 keV, and the decay showed a significant break after similar to 2 s. The spectrum provides strong constraints on the standard synchrotron model, indicating that alternative mechanisms may give rise to the emission at these energies.
|Autori:||Axelsson M; Baldini L; Barbiellini G; Baring MG; Bellazzini R; Bregeon J; Brigida M; Bruel P; Buehler R; Caliandro GA; Cameron RA; Caraveo PA; Cecchi C; Chaves RCG; Chekhtman A; Chiang J; Claus R; Conrad J; Cutini S; D'Ammando F; de Palma F; Dermer CD; Silva EDE; Drell PS; Favuzzi C; Fegan SJ; Ferrara EC; Focke WB; Fukazawa Y; Fusco P; Gargano F; Gasparrini D; Gehrels N; Germani S; Giglietto N; Giroletti M; Godfrey G; Guiriec S; Hadasch D; Hanabata Y; Hayashida M; Hou X; Iyyani S; Jackson MS; Kocevski D; Kuss M; Larsson J; Larsson S; Longo F; Loparco F; Lundman C; Mazziotta MN; McEnery JE; Mizuno T; Monzani ME; Moretti E; Morselli A; Murgia S; Nuss E; Nymark T; Ohno M; Omodei N; Pesce-Rollins M; Piron F; Pivato G; Racusin JL; Raino S; Razzano M; Razzaque S; Reimer A; Roth M; Ryde F; Sanchez DA; Sgro C; Siskind EJ; Spandre G; Spinelli P; Stamatikos M; Tibaldo L; Tinivella M; Usher TL; Vandenbroucke J; Vasileiou V; Vianello G; Vitale V; Waite AP; Winer BL; Wood KS; Burgess JM; Bhat PN; Bissaldi E; Briggs MS; Connaughton V; Fishman G; Fitzpatrick G; Foley S; Gruber D; Kippen RM; Kouveliotou C; Jenke P; McBreen S; McGlynn S; Meegan C; Paciesas WS; Pelassa V; Preece R; Tierney D; von Kienlin A; Wilson-Hodge C; Xiong S; Pe'er A|
|Titolo:||GRB110721A: AN EXTREME PEAK ENERGY AND SIGNATURES OF THE PHOTOSPHERE|
|Anno del prodotto:||2012|
|Digital Object Identifier (DOI):||10.1088/2041-8205/757/2/L31|
|Appare nelle tipologie:||1.1 Articolo in rivista|