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Title: NEW FERMI-LAT EVENT RECONSTRUCTION REVEALS MORE HIGH-ENERGY GAMMA RAYS FROM GAMMA-RAY BURSTS

Journal Article · · Astrophysical Journal
 [1];  [2]; ; ; ;  [3];  [4];  [5];  [6]; ; ; ;  [7];  [8];  [9];  [10]
  1. Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States)
  2. Universita di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
  3. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
  4. Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France)
  5. Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States)
  6. Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS/IN2P3, F-34095 Montpellier (France)
  7. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
  8. Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra'anana 43537 (Israel)
  9. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
  10. Department of Physics, University of Johannesburg, Auckland Park 2006 (South Africa)

Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy ({approx}147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

OSTI ID:
22133928
Journal Information:
Astrophysical Journal, Vol. 774, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
Country of Publication:
United States
Language:
English

Cited By (23)

Unidentified γ -ray emission towards the SNR Kes 41 revisited journal November 2018
Broadband characterisation of the very intense TeV flares of the blazar 1ES 1959+650 in 2016 journal June 2020
SEARCH FOR GeV GAMMA-RAY BURSTS WITH THE ARGO-YBJ DETECTOR: SUMMARY OF EIGHT YEARS OF OBSERVATIONS journal September 2014
Constraints on very high Energy Emission from grb 130427a journal October 2014
Testing the anisotropy in the angular distribution of Fermi/GBM gamma-ray bursts journal September 2017
The beamed jet and quasar core of the distant blazar 4C 71.07 journal August 2019
Resolving the Extragalactic γ -Ray Background above 50 GeV with the Fermi Large Area Telescope journal April 2016
Wimp searches with gamma rays in the Fermi era: Challenges, methods and results journal December 2015
Main physics results of the ARGO-YBJ experiment journal August 2014
Relativistic Jets in Gamma-Ray-Emitting Narrow-Line Seyfert 1 Galaxies journal November 2019
Identifying the 3FHL Catalog. II. Results of the KOSMOS Optical Spectroscopy Campaign journal October 2018
X-Ray and GeV Gamma-Ray Variability of the Radio Galaxy NGC 1275 journal March 2018
Deriving the Contribution of Blazars to the Fermi -LAT Extragalactic γ -ray Background at E > 10 GeV with Efficiency Corrections and Photon Statistics journal March 2018
The Bright and the Slow—GRBs 100724B and 160509A with High-energy Cutoffs at ≲100 MeV journal September 2018
2FHL J0826.1–4500: Discovery of a Possible Shock–Cloud Interaction on the Western Edge of the Vela Supernova Remnant journal January 2019
Broadband characterisation of the very intense TeV flares of the blazar 1ES 1959+650 in 2016 text January 2020
Constraints on very High Energy Emission from GRB 130427A text January 2014
Resolving the Extragalactic $\gamma$-Ray Background above 50 GeV with the Fermi Large Area Telescope text January 2016
Search for GeV Gamma Ray Bursts with the ARGO-YBJ Detector: Summary of Eight Years of Observations text January 2015
WIMP searches with gamma rays in the Fermi era: challenges, methods and results text January 2015
Identifying the 3FHL catalog: I. Results of the KOSMOS optical spectroscopy campaign text January 2018
The beamed jet and quasar core of the distant blazar 4C 71.07 text January 2019
Broadband characterisation of the very intense TeV flares of the blazar 1ES 1959+650 in 2016 text January 2020

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