Accession Number DE2012-1045814
Title Detection of a Spectral Break in the Extra Hard Component of GRB 090926A.
Publication Date Jan 2011
Media Count 31p
Personal Author G. Barbiellini J. Ballet K. Asano L. Baldini M. Ackerman M. Ajello M. Axelsson
Abstract We report on the observation of the bright, long gamma-ray burst, GRB 090926A, by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. GRB 090926A shares several features with other bright LAT bursts. In particular, it clearly shows a short spike in the light curve that is present in all detectors that see the burst, and this in turn suggests that there is a common region of emission across the entire Fermi energy range. In addition, while a separate high-energy power-law component has already been observed in other GRBs, here we report for the first time the detection with good significance of a high-energy spectral break (or cutoff) in this power-law component around 1.4 GeV in the time-integrated spectrum. If the spectral break is caused by opacity to electron-positron pair production within the source, then this observation allows us to compute the bulk Lorentz factor for the outflow, rather than a lower limit.
Keywords Detection
Energy range
Eolectron-positron interactions
Fermi gamma ray space telescope
Gamma ray burst
Pair production

Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 54C - Astrophysics
54D - Cosmic Ray Research
Corporate Author Stanford Research Inst., Menlo Park, CA.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1303
Contract Number DE-AC02-76SF00515

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