Detection of a spectral break in the extra hard component of GRB 090926A
Markus Ackermann
,
Marco Ajello
,
K. Asano
,
Magnus Axelsson
,
Luca Baldini
,
Jean Ballet
(1)
,
Guido 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
,
M. S. Briggs
,
M. Brigida
,
Pascal Bruel
(2)
,
R. Buehler
,
S. Buson
,
G. A. Caliandro
,
R. A. Cameron
,
P. A. Caraveo
,
S. Carrigan
,
J. M. Casandjian
(1)
,
C. Cecchi
,
Ö. Çelik
,
V. Chaplin
,
E. Charles
,
A. Chekhtman
,
J. Chiang
,
S. Ciprini
,
R. Claus
,
J. Cohen-Tanugi
(3)
,
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
(2)
,
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
(1)
,
J. E. Grove
,
S. Guiriec
,
D. Hadasch
,
Y. Hanabata
,
A. K. Harding
,
K. Hayashi
,
M. Hayashida
,
E. Hays
,
D. Horan
(2)
,
R. E. Hughes
,
R. Itoh
,
G. Jóhannesson
,
A. S. Johnson
,
W. N. Johnson
,
T. Kamae
,
H. Katagiri
,
J. Kataoka
,
R. M. Kippen
,
Jürgen Knödlseder
(4)
,
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
(3)
,
P. Mészáros
,
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
(1)
,
S. Nishino
,
P. L. Nolan
,
J. P. Norris
,
E. Nuss
(3)
,
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
(3)
,
M. Pepe
,
M. Pesce-Rollins
,
V. Petrosian
,
F. Piron
(3)
,
T.A. Porter
,
R. Preece
,
J. L. Racusin
,
S. Rainò
,
R. Rando
,
A. Rau
,
M. Razzano
,
S. Razzaque
,
A. Reimer
,
O. Reimer
,
T. Reposeur
(5)
,
L. C. Reyes
,
J. Ripken
,
S. Ritz
,
M. Roth
,
F. Ryde
,
H. F.-W. Sadrozinski
,
A. Sander
,
J. D. Scargle
,
T. L. Schalk
,
C. Sgrò
,
E. J. Siskind
,
P. D. Smith
,
G. Spandre
,
P. Spinelli
,
M. Stamatikos
,
F. W. Stecker
,
M. S. Strickman
,
D. J. Suson
,
H. Tajima
,
H. Takahashi
,
T. Tanaka
,
Y. Tanaka
,
J. B. Thayer
,
J. G. Thayer
,
L. Tibaldo
(1)
,
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
(4)
,
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
Markus Ackermann
- Function : Author
Marco Ajello
- Function : Author
K. Asano
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Magnus Axelsson
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Luca Baldini
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Guido Barbiellini
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M. G. Baring
- Function : Author
D. Bastieri
- Function : Author
K. Bechtol
- Function : Author
R. Bellazzini
- Function : Author
B. Berenji
- Function : Author
P. N. Bhat
- Function : Author
E. Bissaldi
- Function : Author
R. D. Blandford
- Function : Author
E. Bonamente
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A. W. Borgland
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A. Bouvier
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J. Bregeon
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A. Brez
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M. S. Briggs
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M. Brigida
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R. Buehler
- Function : Author
S. Buson
- Function : Author
G. A. Caliandro
- Function : Author
R. A. Cameron
- Function : Author
P. A. Caraveo
- Function : Author
S. Carrigan
- Function : Author
C. Cecchi
- Function : Author
Ö. Çelik
- Function : Author
V. Chaplin
- Function : Author
E. Charles
- Function : Author
A. Chekhtman
- Function : Author
J. Chiang
- Function : Author
S. Ciprini
- Function : Author
R. Claus
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J. Cohen-Tanugi
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V. Connaughton
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J. Conrad
- Function : Author
S. Cutini
- Function : Author
C. D. Dermer
- Function : Author
A. de Angelis
- Function : Author
F. de Palma
- Function : Author
B. L. Dingus
- Function : Author
E. Do Couto E Silva
- Function : Author
P. S. Drell
- Function : Author
R. Dubois
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C. Favuzzi
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S. J. Fegan
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E. C. Ferrara
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M. Frailis
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Y. Fukazawa
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S. Funk
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P. Fusco
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F. Gargano
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D. Gasparrini
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N. Gehrels
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S. Germani
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N. Giglietto
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F. Giordano
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M. Giroletti
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T. Glanzman
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G. Godfrey
- Function : Author
A. Goldstein
- Function : Author
J. Granot
- Function : Author
J. Greiner
- Function : Author
J. E. Grove
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S. Guiriec
- Function : Author
D. Hadasch
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Y. Hanabata
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A. K. Harding
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K. Hayashi
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M. Hayashida
- Function : Author
E. Hays
- Function : Author
R. E. Hughes
- Function : Author
R. Itoh
- Function : Author
G. Jóhannesson
- Function : Author
A. S. Johnson
- Function : Author
W. N. Johnson
- Function : Author
T. Kamae
- Function : Author
H. Katagiri
- Function : Author
J. Kataoka
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R. M. Kippen
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Jürgen Knödlseder
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D. Kocevski
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M. Kuss
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J. Lande
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L. Latronico
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S.-H. Lee
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M. N. Mazziotta
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S. Mcbreen
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J. E. Mcenery
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S. Mcglynn
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C. Meegan
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P. Mészáros
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P. F. Michelson
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T. Mizuno
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C. Monte
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M. E. Monzani
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E. Moretti
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A. Morselli
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S. Nishino
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P. L. Nolan
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J. P. Norris
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T. Ohsugi
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A. Okumura
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N. Omodei
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E. Orlando
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J. F. Ormes
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M. Ozaki
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D. Paneque
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J. H. Panetta
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D. Parent
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M. Pepe
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M. Pesce-Rollins
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V. Petrosian
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F. Piron
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T.A. Porter
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R. Preece
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S. Rainò
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R. Rando
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A. Rau
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M. Razzano
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S. Razzaque
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A. Reimer
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F. Ryde
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H. F.-W. Sadrozinski
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A. Sander
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T. L. Schalk
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C. Sgrò
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E. J. Siskind
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P. D. Smith
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G. Spandre
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P. Spinelli
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M. Stamatikos
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F. W. Stecker
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M. S. Strickman
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D. J. Suson
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H. Tajima
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H. Takahashi
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T. Tanaka
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Y. Tanaka
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J. B. Thayer
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K. Toma
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D. F. Torres
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G. Tosti
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A. Tramacere
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Y. Uchiyama
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T. Uehara
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T. L. Usher
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J. Vandenbroucke
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A. J. van Der Horst
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A. von Kienlin
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A. P. Waite
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B. L. Winer
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K. S. Wood
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X. F. Wu
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R. Yamazaki
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Z. Yang
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T. Ylinen
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M. Ziegler
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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.