CaltechAUTHORS
Published April 4, 2009 | Version Published
Journal Article Open

The redshift and afterglow of the extremely energetic gamma-ray burst GRB 080916C

Creators

  • 1. ROR icon Max Planck Institute for Extraterrestrial Physics
  • 2. ROR icon Technical University of Munich
  • 3. ROR icon California Institute of Technology
  • 4. ROR icon Pennsylvania State University
  • 5. ROR icon SLAC National Accelerator Laboratory
  • 6. ROR icon Harvard University
  • 7. ROR icon University of California, Berkeley
  • 8. ROR icon Thüringer Landessternwarte Tautenburg
  • 9. ROR icon European Southern Observatory
  • 10. ROR icon University College Dublin
  • 11. ROR icon Kyoto University
  • 12. ROR icon Nagoya University
  • 13. ROR icon Eötvös Loránd University

Abstract

Context. The detection of GeV photons from gamma-ray bursts (GRBs) has important consequences for the interpretation and modelling of these most-energetic cosmological explosions. The full exploitation of the high-energy measurements relies, however, on accurate knowledge of the distance to the events. Aims. Here we report on the discovery of the afterglow and subsequent redshift determination of GRB 080916C, the first GRB detected by the Fermi Gamma-Ray Space Telescope with high significance detection of photons at energies >0.1 GeV. Methods. Observations were done with the 7-channel "Gamma-Ray Optical and Near-infrared Detector" (GROND) at the 2.2 m MPI/ESO telescope, the SIRIUS instrument at the Nagoya-SAAO 1.4 m telescope in South Africa, and the GMOS instrument at Gemini-S. Results. The afterglow photometric redshift of , based on simultaneous 7-filter observations with GROND, places GRB 080916C among the top 5% most distant GRBs and makes it the most energetic GRB known to date. The detection of GeV photons from such a distant event is unexpected because of the predicted opacity due to interaction with the extragalactic background light. The observed gamma-ray variability in the prompt emission, together with the redshift, suggests a lower limit for the Lorentz factor of the ultra-relativistic ejecta of . This value rivals any previous measurements of in GRBs and strengthens the extreme nature of GRB 080916C.

Additional Information

© 2009 ESO. Received 22 December 2008. Accepted 7 February 2009. T.K. acknowledges support by the DFG cluster of excellence "Origin and Structure of the Universe". Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz- Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). Av.K. acknowledges funding through DLR 50 QV 0301, and X.L.Z. through DLR 50 OG 0502. S.M.B. acknowledges an EUMarie Curie Fellowship in Framework 6. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. We thank X. Wu for a discussion oon the α − β relation. Max Planck: 2.2m (GROND), Gemini: South (GMOS), SAAO: Nagoya (SIRIUS), INTEGRAL (SPI-ACS).

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Additional details

Identifiers

Eprint ID
15383
Resolver ID
CaltechAUTHORS:20090828-080524923

Funding

Deutsche Forschungsgemeinschaft (DFG)
HA 1850/28-1
Deutsches Zentrum für Luft- und Raumfahrt (DLR)
50 QV 0301
Deutsches Zentrum für Luft- und Raumfahrt (DLR)
50 OG 0502

Dates

Created
2009-09-03
Created from EPrint's datestamp field
Updated
2021-11-08
Created from EPrint's last_modified field