Fermi Observations Of High-Energy Gamma-Ray Emission From Grb 090217a

Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini Amidei, Guido; Baring, M. G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bhat, P. N.; Bissaldi, Elisabetta; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Celik, O.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen Tanugi, J.; Connaughton, V.; Conrad, J.; Cutini, S.; Dermer, C. D.; Angelis, A. D.; Palma, F. D.; Digel, S. W.; Silva, E. D. Couto E.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Granot, J.; Grenier, I. A.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hays, E.; Horan, D.; Hughes, R. E.; Johannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kippen, R. M.; Knodlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. H.; Garde, M. L.; Longo, Francesco; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; Mcbreen, S.; Mcenery, J. E.; Mcglynn, S.; Meegan, C.; Mehault, J.; Meszaros, P.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce Rollins, M.; Petrosian, V.; Piron, F.; Porter, T. A.; Preece, R.; Racusin, J. L.; Raino, S.; Rando, R.; Rau, A.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Ripken, J.; Roth, M.; Ryde, F.; Sadrozinski, H. F. W.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sgro, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uehara, T.; Usher, T. L.; Vandenbroucke, J.; Van Der Horst, A. J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Kienlin, A. V.; Waite, A. P.; Wang, P.; Wilson Hodge, C.; Winer, B. L.; Wood, K. S.; X. F., Wu; Yamazaki, R.; Yang, Z.; Ylinen, T.; Ziegler, M.

doi:10.1088/2041-8205/717/2/L127

The Fermi observatory is advancing our knowledge of gamma-ray bursts (GRBs) through pioneering observations at high energies, covering more than seven decades in energy with the two on-board detectors, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). Here, we report on the observation of the long GRB 090217A which triggered the GBM and has been detected by the LAT with a significance greater than 9 sigma. We present the GBM and LAT observations and on-ground analyses, including the time-resolved spectra and the study of the temporal profile from 8 keV up to similar to 1 GeV. All spectra are well reproduced by a Band model. We compare these observations to the first two LAT-detected, long bursts GRB 080825C and GRB 080916C. These bursts were found to have time-dependent spectra and exhibited a delayed onset of the high-energy emission, which are not observed in the case of GRB 090217A. We discuss some theoretical implications for the high-energy emission of GRBs.

Fermi Observations Of High-Energy Gamma-Ray Emission From Grb 090217a / Ackermann, M., Ajello, M., Baldini, L., Ballet, J., BARBIELLINI AMIDEI, G., Baring, M.G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Bhat, P.N., Bissaldi, E., Blandford, R.D., Bonamente, E., Borgland, A.W., Bouvier, A., Bregeon, J., Brez, A., Briggs, M.S., Brigida, M., et al.. - In: THE ASTROPHYSICAL JOURNAL LETTERS. - ISSN 2041-8205. - STAMPA. - 717:(2010), pp. L127-L132. [10.1088/2041-8205/717/2/L127]