FERMI OBSERVATIONS OF HIGH-ENERGY GAMMA-RAY EMISSION FROM GRB 090217A

Journal Article · Sat Jul 10 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/717/2/L127· OSTI ID:21451040

Ackermann, M; Ajello, M; Bechtol, K; Berenji, B; Blandford, R D; Borgland, A W; Bouvier, A ^[1]; Baldini, L; Bellazzini, R; Bregeon, J; Brez, A ^[2]; Ballet, J ^[3]; Barbiellini, G ^[4]; Baring, M G ^[5]; Bastieri, D ^[6]; Bhat, P N; Briggs, M S ^[7]; Bissaldi, E ^[8]; Bonamente, E ^[9]; Brigida, M ^[10]

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1. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
2. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
3. Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France)
4. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
5. Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States)
6. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
7. Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States)
8. Max-Planck Institut fuer extraterrestrische Physik, 85748 Garching (Germany)
9. Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)
10. Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy)

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 {approx}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.

• OSTI ID: 21451040
• Journal Information: Astrophysical Journal Letters, Vol. 717, Issue 2; Other Information: DOI: 10.1088/2041-8205/717/2/L127; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COSMIC GAMMA BURSTS
EMISSION
EMISSION SPECTRA
GAMMA RADIATION
TELESCOPES
TIME DEPENDENCE
TIME RESOLUTION
COSMIC RADIATION
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
PRIMARY COSMIC RADIATION
RADIATIONS
RESOLUTION
SPECTRA
TIMING PROPERTIES