GRB110721A: AN EXTREME PEAK ENERGY AND SIGNATURES OF THE PHOTOSPHERE
- 17 September 2012
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal Letters
- Vol. 757 (2), L31
- https://doi.org/10.1088/2041-8205/757/2/l31
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 s (in the GBM) and had a peak flux of (5.7 ± 0.2) × 10–5 erg s–1 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 ± 2 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 ± 0.10. The temperature of the blackbody component also decreased, starting from ~80 keV, and the decay showed a significant break after ~2 s. The spectrum provides strong constraints on the standard synchrotron model, indicating that alternative mechanisms may give rise to the emission at these energies.This publication has 33 references indexed in Scilit:
- CONSTRAINTS ON THE SYNCHROTRON SHOCK MODEL FOR THEFERMIGRB 090820A OBSERVED BY GAMMA-RAY BURST MONITORThe Astrophysical Journal, 2011
- Handbook of X-ray AstronomyPublished by Cambridge University Press (CUP) ,2011
- Collisional mechanism for gamma-ray burst emissionMonthly Notices of the Royal Astronomical Society, 2010
- FERMIOBSERVATIONS OF GRB 090510: A SHORT-HARD GAMMA-RAY BURST WITH AN ADDITIONAL, HARD POWER-LAW COMPONENT FROM 10 keV TO GeV ENERGIESThe Astrophysical Journal, 2010
- FERMI OBSERVATIONS OF GRB 090902B: A DISTINCT SPECTRAL COMPONENT IN THE PROMPT AND DELAYED EMISSIONThe Astrophysical Journal, 2009
- THE LARGE AREA TELESCOPE ON THEFERMI GAMMA-RAY SPACE TELESCOPEMISSIONThe Astrophysical Journal, 2009
- Ground-based calibration and characterization of the Fermi gamma-ray burst monitor detectorsExperimental Astronomy, 2009
- Observation of an Extra Emission around 2 MeV in the Spectrum of an Intense Gamma‐Ray BurstThe Astrophysical Journal, 2000
- BATSE observations of gamma-ray burst spectra. 2: Peak energy evolution in bright, long burstsThe Astrophysical Journal, 1995
- BATSE observations of gamma-ray burst spectra. I - Spectral diversityThe Astrophysical Journal, 1993