Detection of a Spectral Break in the Extra Hard Component of GRB 090926A

Research output: Contribution to journalArticle

Abstract

We report on the observation of the bright, long gamma-ray burst, GRB 090926A, by the Gamma-ray Burst Monitor 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 gamma-ray bursts, 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.

Details

Authors
  • M. Ackermann
  • M. Ajello
  • K. Asano
  • Magnus Axelsson
  • L. Baldini
  • J. Ballet
  • G. Barbiellini
  • M. G. Baring
  • D. Bastieri
  • K. Bechtol
  • R. Bellazzini
  • B. Berenji
  • P. N. Bhat
  • E. Bissaldi
  • R. D. Blandford
  • E. Bonamente
  • A. W. Borgland
  • A. Bouvier
  • J. Bregeon
  • A. Brez
  • And 171 others
  • M. S. Briggs
  • M. Brigida
  • P. Bruel
  • R. Buehler
  • S. Buson
  • G. A. Caliandro
  • R. A. Cameron
  • P. A. Caraveo
  • S. Carrigan
  • J. M. Casandjian
  • C. Cecchi
  • O. Celik
  • V. Chaplin
  • E. Charles
  • A. Chekhtman
  • J. Chiang
  • S. Ciprini
  • R. Claus
  • J. Cohen-Tanugi
  • V. Connaughton
  • J. Conrad
  • S. Cutini
  • C. D. Dermer
  • A. De Angelis
  • F. De Palma
  • B. L. Dingus
  • E. Do Couto E. Silva
  • P. S. Drell
  • R. Dubois
  • C. Favuzzi
  • S. J. Fegan
  • E. C. Ferrara
  • W. B. Focke
  • M. Frailis
  • Y. Fukazawa
  • S. Funk
  • P. Fusco
  • F. Gargano
  • D. Gasparrini
  • N. Gehrels
  • S. Germani
  • N. Giglietto
  • F. Giordano
  • M. Giroletti
  • T. Glanzman
  • G. Godfrey
  • A. Goldstein
  • J. Granot
  • J. Greiner
  • I. A. Grenier
  • J. E. Grove
  • S. Guiriec
  • D. Hadasch
  • Y. Hanabata
  • A. K. Harding
  • K. Hayashi
  • M. Hayashida
  • E. Hays
  • D. Horan
  • R. E. Hughes
  • R. Itoh
  • G. Johannesson
  • A. S. Johnson
  • W. N. Johnson
  • T. Kamae
  • H. Katagiri
  • J. Kataoka
  • R. M. Kippen
  • J. Knoedlseder
  • D. Kocevski
  • C. Kouveliotou
  • M. Kuss
  • J. Lande
  • L. Latronico
  • S. -H. Lee
  • M. Llena Garde
  • F. Longo
  • F. Loparco
  • M. N. Lovellette
  • P. Lubrano
  • A. Makeev
  • M. N. Mazziotta
  • S. McBreen
  • J. E. McEnery
  • S. McGlynn
  • C. Meegan
  • J. Mehault
  • P. Meszaros
  • P. F. Michelson
  • T. Mizuno
  • C. Monte
  • M. E. Monzani
  • E. Moretti
  • A. Morselli
  • I. V. Moskalenko
  • S. Murgia
  • H. Nakajima
  • T. Nakamori
  • M. Naumann-Godo
  • S. Nishino
  • P. L. Nolan
  • J. P. Norris
  • E. Nuss
  • M. Ohno
  • T. Ohsugi
  • A. Okumura
  • N. Omodei
  • E. Orlando
  • J. F. Ormes
  • M. Ozaki
  • W. S. Paciesas
  • D. Paneque
  • J. H. Panetta
  • D. Parent
  • V. Pelassa
  • M. Pepe
  • M. Pesce-Rollins
  • V. Petrosian
  • F. Piron
  • T. A. Porter
  • R. Preece
  • J. L. Racusin
  • S. Raino
  • R. Rando
  • A. Rau
  • M. Razzano
  • S. Razzaque
  • A. Reimer
  • O. Reimer
  • T. Reposeur
  • L. C. Reyes
  • J. Ripken
  • S. Ritz
  • M. Roth
  • F. Ryde
  • H. F. -W. Sadrozinski
  • A. Sander
  • J. D. Scargle
  • M. S. Strickman
  • D. J. Suson
  • H. Tajima
  • H. Takahashi
  • T. Tanaka
  • Y. Tanaka
  • J. B. Thayer
  • J. G. Thayer
  • L. Tibaldo
  • D. Tierney
  • K. Toma
  • D. F. Torres
  • G. Tosti
  • A. Tramacere
  • Y. Uchiyama
  • T. Uehara
  • T. L. Usher
  • J. Vandenbroucke
  • A. J. van der Horst
  • V. Vasileiou
  • N. Vilchez
  • V. Vitale
  • A. von Kienlin
  • A. P. Waite
  • P. Wang
  • C. Wilson-Hodge
  • B. L. Winer
  • K. S. Wood
  • X. F. Wu
  • R. Yamazaki
  • Z. Yang
  • T. Ylinen
  • M. Ziegler
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology

Keywords

  • gamma-ray burst: individual (GRB 090926A)
Original languageEnglish
JournalAstrophysical Journal
Volume729
Issue number2
Publication statusPublished - 2011
Publication categoryResearch
Peer-reviewedYes