GRB110721A: An extreme peak energy and signatures of the photosphere
Magnus Axelsson
,
Luca Baldini
,
Guido Barbiellini
,
M. G. Baring
,
R. Bellazzini
,
J. Bregeon
,
M. Brigida
,
Pascal Bruel
(1)
,
R. Buehler
,
G. A. Caliandro
,
R. A. Cameron
,
P. A. Caraveo
,
C. Cecchi
,
R.C.G. Chaves
(2)
,
A. Chekhtman
,
J. Chiang
,
R. Claus
,
J. Conrad
,
S. Cutini
,
F. d'Ammando
,
F. de Palma
,
C. D. Dermer
,
E. Do Couto E Silva
,
P. S. Drell
,
C. Favuzzi
,
S. J. Fegan
(1)
,
E. C. Ferrara
,
W. B. Focke
,
Y. Fukazawa
,
P. Fusco
,
F. Gargano
,
D. Gasparrini
,
N. Gehrels
,
S. Germani
,
N. Giglietto
,
M. Giroletti
,
G. Godfrey
,
S. Guiriec
,
D. Hadasch
,
Y. Hanabata
,
M. Hayashida
,
X. Hou
(3)
,
S. Iyyani
,
M. S. Jackson
,
D. Kocevski
,
M. Kuss
,
J. Larsson
,
S. Larsson
,
F. Longo
,
F. Loparco
,
C. Lundman
,
M. N. Mazziotta
,
J. E. Mcenery
,
T. Mizuno
,
M. E. Monzani
,
E. Moretti
,
A. Morselli
,
S. Murgia
,
E. Nuss
(4)
,
T. Nymark
,
M. Ohno
,
N. Omodei
,
M. Pesce-Rollins
,
F. Piron
(4)
,
G. Pivato
,
J. L. Racusin
,
S. Rain'O
,
M. Razzano
,
S. Razzaque
,
A. Reimer
,
M. Roth
,
F. Ryde
,
D.A. Sanchez
,
C. Sgr'O
,
E. J. Siskind
,
G. Spandre
,
P. Spinelli
,
M. Stamatikos
,
L. Tibaldo
,
M. Tinivella
,
T. L. Usher
,
J. Vandenbroucke
,
V. Vasileiou
(4)
,
G. Vianello
,
V. Vitale
,
A. P. Waite
,
B. L. Winer
,
K. S. Wood
,
J. M. Burgess
,
P. N. Bhat
,
E. Bissaldi
,
M. S. Briggs
,
V. Connaughton
,
G. Fishman
,
G. Fitzpatrick
,
S. Foley
,
D. Gruber
,
R. M. Kippen
,
C. Kouveliotou
,
P. Jenke
,
S. Mcbreen
,
S. Mcglynn
,
C. Meegan
,
W. S. Pacisas
,
V. Pelassa
(4)
,
R. Preece
,
D. Tierney
,
A. von Kienlin
,
C. Wilson-Hodge
,
S. Xiong
,
A. Pe'Er
Magnus Axelsson
- Function : Author
Luca Baldini
- Function : Author
Guido Barbiellini
- Function : Author
M. G. Baring
- Function : Author
R. Bellazzini
- Function : Author
J. Bregeon
- Function : Author
- PersonId : 741214
- IdHAL : johan-bregeon
- ORCID : 0000-0002-6790-5328
- IdRef : 095856943
M. Brigida
- Function : Author
R. Buehler
- Function : Author
G. A. Caliandro
- Function : Author
R. A. Cameron
- Function : Author
P. A. Caraveo
- Function : Author
C. Cecchi
- Function : Author
A. Chekhtman
- Function : Author
J. Chiang
- Function : Author
R. Claus
- Function : Author
J. Conrad
- Function : Author
S. Cutini
- Function : Author
F. d'Ammando
- Function : Author
F. de Palma
- Function : Author
C. D. Dermer
- Function : Author
E. Do Couto E Silva
- Function : Author
P. S. Drell
- Function : Author
C. Favuzzi
- Function : Author
S. J. Fegan
- Function : Author
- PersonId : 740343
- IdHAL : stephen-fegan
- ORCID : 0000-0002-9978-2510
- IdRef : 253133149
E. C. Ferrara
- Function : Author
W. B. Focke
- Function : Author
Y. Fukazawa
- Function : Author
- PersonId : 760581
- ORCID : 0000-0002-0921-8837
P. Fusco
- Function : Author
F. Gargano
- Function : Author
D. Gasparrini
- Function : Author
N. Gehrels
- Function : Author
S. Germani
- Function : Author
N. Giglietto
- Function : Author
- PersonId : 755413
- ORCID : 0000-0002-9021-2888
M. Giroletti
- Function : Author
G. Godfrey
- Function : Author
S. Guiriec
- Function : Author
D. Hadasch
- Function : Author
- PersonId : 761675
- ORCID : 0000-0001-8663-6461
Y. Hanabata
- Function : Author
M. Hayashida
- Function : Author
S. Iyyani
- Function : Author
M. S. Jackson
- Function : Author
D. Kocevski
- Function : Author
M. Kuss
- Function : Author
J. Larsson
- Function : Author
S. Larsson
- Function : Author
F. Longo
- Function : Author
- PersonId : 755442
- ORCID : 0000-0003-2501-2270
F. Loparco
- Function : Author
C. Lundman
- Function : Author
M. N. Mazziotta
- Function : Author
J. E. Mcenery
- Function : Author
T. Mizuno
- Function : Author
M. E. Monzani
- Function : Author
E. Moretti
- Function : Author
- PersonId : 761109
- ORCID : 0000-0001-5477-9097
A. Morselli
- Function : Author
S. Murgia
- Function : Author
T. Nymark
- Function : Author
M. Ohno
- Function : Author
N. Omodei
- Function : Author
M. Pesce-Rollins
- Function : Author
- PersonId : 760585
- ORCID : 0000-0003-1790-8018
F. Piron
- Function : Author
- PersonId : 172749
- IdHAL : frederic-piron
- ORCID : 0000-0001-6885-7156
G. Pivato
- Function : Author
J. L. Racusin
- Function : Author
S. Rain'O
- Function : Author
M. Razzano
- Function : Author
S. Razzaque
- Function : Author
A. Reimer
- Function : Author
- PersonId : 755465
- ORCID : 0000-0001-8604-7077
M. Roth
- Function : Author
F. Ryde
- Function : Author
D.A. Sanchez
- Function : Author
C. Sgr'O
- Function : Author
E. J. Siskind
- Function : Author
G. Spandre
- Function : Author
P. Spinelli
- Function : Author
M. Stamatikos
- Function : Author
L. Tibaldo
- Function : Author
M. Tinivella
- Function : Author
T. L. Usher
- Function : Author
J. Vandenbroucke
- Function : Author
G. Vianello
- Function : Author
V. Vitale
- Function : Author
- PersonId : 760184
- ORCID : 0000-0001-8040-7852
A. P. Waite
- Function : Author
B. L. Winer
- Function : Author
K. S. Wood
- Function : Author
J. M. Burgess
- Function : Author
P. N. Bhat
- Function : Author
E. Bissaldi
- Function : Author
M. S. Briggs
- Function : Author
V. Connaughton
- Function : Author
G. Fishman
- Function : Author
G. Fitzpatrick
- Function : Author
S. Foley
- Function : Author
D. Gruber
- Function : Author
R. M. Kippen
- Function : Author
C. Kouveliotou
- Function : Author
P. Jenke
- Function : Author
S. Mcbreen
- Function : Author
S. Mcglynn
- Function : Author
C. Meegan
- Function : Author
W. S. Pacisas
- Function : Author
R. Preece
- Function : Author
D. Tierney
- Function : Author
A. von Kienlin
- Function : Author
C. Wilson-Hodge
- Function : Author
S. Xiong
- Function : Author
A. Pe'Er
- Function : Author
Abstract
GRB110721A was observed by the Fermi Gamma-ray Space Telescope using its two instruments the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). The burst consisted of one major emission episode which lasted for ~24.5 seconds (in the GBM) and had a peak flux of 5.7\pm0.2 x 10^{-5} erg/s/cm^2. The time-resolved emission spectrum is best modeled with a combination of a Band function and a blackbody spectrum. The peak energy of the Band component was initially 15\pm2 MeV, which is the highest value ever detected in a GRB. This measurement was made possible by combining GBM/BGO data with LAT Low Energy Events to achieve continuous 10--100 MeV coverage. The peak energy later decreased as a power law in time with an index of -1.89\pm0.10. The temperature of the blackbody component also decreased, starting from ~80 keV, and the decay showed a significant break after ~2 seconds. The spectrum provides strong constraints on the standard synchrotron model, indicating that alternative mechanisms may give rise to the emission at these energies.