HESS OBSERVATIONS OF THE PROMPT AND AFTERGLOW PHASES OF GRB 060602B

We report on the first completely simultaneous observation of a gamma-ray burst (GRB) using an array of Imaging Atmospheric Cherenkov Telescopes which is sensitive to photons in the very-high-energy (VHE) gamma-ray range (>~100 GeV). On 2006 June 2, the Swift Burst Alert Telescope (BAT) registered an unusually soft gamma-ray burst (GRB 060602B). The burst position was under observation using the High Energy Stereoscopic System (H.E.S.S.) at the time the burst occurred. Data were taken before, during, and after the burst. A total of 5 hours of observations were obtained during the night of 2006 June 2-3, and 5 additional hours were obtained over the next 3 nights. No VHE gamma-ray signal was found during the period covered by the H.E.S.S. observations. The 99% confidence level flux upper limit (>1 TeV) for the prompt phase (9s) of GRB 060602B is 2.9x10^-9 erg cm^-2 s^-1. Due to the very soft BAT spectrum of the burst compared to other Swift GRBs and its proximity to the Galactic center, the burst is likely associated with a Galactic X-ray burster, although the possibility of it being a cosmological GRB cannot be ruled out. We discuss the implications of our flux limits in the context of these two bursting scenarios.

HESS Collaboration F. Aharonian | et al | A. R. Bazer-Bachi | K. J. Orford | Nicolas Produit | T. Bulik | E. Moulin | T. Lohse | T. Mccomb | M. Kerschhaggl | W. Domainko | W. Benbow | S. Rosier-Lees | A. Quirrenbach | D. Emmanoulopoulos | M. Renaud | C. Venter | M. Raue | F. Dubois | S. Ohm | C. Stegmann | W. Hofmann | M. Hauser | R. Schlickeiser | L. Chounet | F. Aharonian | D. Horns | Y. Gallant | K. Kosack | F. Feinstein | P. Goret | M. Naumann-Godo | A. Santangelo | L. Drury | S. Gabici | S. Wagner | M. Beilicke | J. Ruppel | M. Vivier | C. Farnier | D. Khangulyan | H. Dickinson | J. Ripken | J. Tavernet | M. Panter | B. Behera | K. Bernlöhr | C. Boisson | I. Braun | A. Djannati-Ataï | G. Dubus | J. Dyks | K. Egberts | A. Fiasson | A. Förster | B. Giebels | J. Glicenstein | G. Henri | G. Hermann | J. Hinton | A. Jacholkowska | I. Jung | K. Katarzyński | B. Khélifi | N. Komin | G. Lamanna | J. Lenain | A. Marcowith | R. Moderski | D. Nedbal | S. Nolan | M. Ostrowski | G. Pedaletti | P. Petrucci | S. Pita | G. Pühlhofer | M. Punch | F. Rieger | L. Rob | B. Rudak | V. Sahakian | U. Schwanke | S. Schwarzburg | S. Schwemmer | H. Sol | R. Steenkamp | R. Terrier | G. Vasileiadis | J. Vialle | P. Vincent | A. Zech | L. Costamante | V. Borrel | B. Degrange | G. Fontaine | E. de Oña Wilhelmi | G. Rowell | R. Chaves | P. Chadwick | Ł. Stawarz | A. Akhperjanian | U. Barres de Almeida | J. Brucker | R. Bühler | I. Büsching | T. Boutelier | A. Clapson | M. Dalton | P. Espigat | B. Glück | D. Hauser | A. Hoffmann | S. Hoppe | D. Keogh | O. Martineau-Huynh | D. Maurin | M. de Naurois | D. Nekrassov | G. Pelletier | B. Raubenheimer | S. Rayner | F. Schöck | A. Shalchi | G. Superina | P. Tam | C. van Eldik | H. Völk | F. Volpe | S. Carrigan | R. Cornils | C. Hadjichristidis | M. Holleran | I. Latham | C. Masterson | A. Zdziarski | J. Osborne | G. Heinzelmann | E. Brion | E. Kendziorra | O. C. de Jager | D. Spangler | J-P. Olive | R. Schröder | T. Lohse | M. Ward | M. Füssling | J. M. Martin | É. Brion | S. Wagner | S. Wagner | K. Orford

[1]  B. Dingus,et al.  Broadband Spectral Properties of Bright High-Energy Gamma-Ray Bursts Observed with BATSE and EGRET , 2008, 0801.1869.

[2]  Neutrino Afterglow from Gamma-Ray Bursts: ~1018 eV , 1999, hep-ph/9909286.

[3]  D. Berley,et al.  Milagro Constraints on Very High Energy Emission from Short-Duration Gamma-Ray Bursts , 2007, 0705.1554.

[4]  A. Hillas,et al.  Differences between gamma-ray and hadronic showers , 1996 .

[5]  G. Gisler,et al.  Evidence for TeV Emission from GRB 970417a , 2000 .

[6]  A. Noutsos,et al.  A low level of extragalactic background light as revealed by γ-rays from blazars , 2005, Nature.

[7]  Ray W. Klebesadel,et al.  Observations of Gamma-Ray Bursts of Cosmic Origin , 1973 .

[8]  R. Cousins,et al.  A Unified Approach to the Classical Statistical Analysis of Small Signals , 1997, physics/9711021.

[9]  B. Mészáros High-Energy Spectral Components in Gamma-Ray Burst Afterglows , 2001, astro-ph/0103229.

[10]  The high-energy gamma-ray fluence and energy spectrum of GRB 970417a from observations with Milagrito , 2003 .

[11]  D. Thompson,et al.  Detection of a γ-ray burst of very long duration and very high energy , 1994, Nature.

[12]  P. Meszaros Gamma-ray bursts , 1998 .

[13]  Z. Dai,et al.  The Inverse Compton Emission Spectra in the Very Early Afterglows of Gamma-Ray Bursts , 2001, astro-ph/0104128.

[14]  CONSTRAINTS ON VERY HIGH ENERGY GAMMA-RAY EMISSION FROM GAMMA-RAY BURSTS , 2005, astro-ph/0503270.

[15]  T. Weekes TeV radiation from galactic sources , 1992 .

[16]  C. Dermer,et al.  High-energy Gamma Rays from Ultra-high-energy Cosmic-Ray Protons in Gamma-Ray Bursts , 1998, astro-ph/9801027.

[17]  B. Degrange,et al.  Towards a network of atmospheric Cherenkov detectors VII : Palaiseau, April 27-29, 2005 , 2005 .

[18]  K. Asano,et al.  Prompt GeV-TeV Emission of Gamma-Ray Bursts Due to High-Energy Protons, Muons, and Electron-Positron Pairs , 2007, 0705.2910.

[19]  N Tonello,et al.  Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303 , 2006, Science.

[20]  Walter H. G. Lewin,et al.  X-ray bursts , 1993 .

[21]  L. Natalucci,et al.  Burst-only sources: probing type I X-ray bursters at low persistent luminosities , 2004 .

[22]  T. Piran Gamma-ray bursts and the fireball model , 1998, astro-ph/9810256.

[23]  Charles D. Dermer,et al.  Beaming, Baryon Loading, and the Synchrotron Self-Compton Component in Gamma-Ray Bursts , 2000 .

[24]  A. Noutsos,et al.  A New Population of Very High Energy Gamma-Ray Sources in the Milky Way , 2005, Science.

[25]  P. Mészáros,et al.  GeV-TeV and X-Ray Flares from Gamma-Ray Bursts , 2006, astro-ph/0601229.

[26]  K. Cheng,et al.  Stationary accelerators around Keplerian disks of aligned magnetized collapsed objects: Pair production and gamma-ray emission , 1991 .

[27]  E.P.J. van den Heuvel,et al.  A catalogue of low-mass X-ray binaries , 2001 .

[28]  N. R. Butler Refined Astrometry and Positions for 179 Swift X-Ray Afterglows , 2007 .

[29]  John Ellis,et al.  Int. J. Mod. Phys. , 2005 .

[30]  D. Hartmann,et al.  Gamma-ray bursts , 1995 .

[31]  Bing Zhang,et al.  GeV and Higher Energy Photon Interactions in Gamma-Ray Burst Fireballs and Surroundings , 2004, astro-ph/0404076.

[32]  A. Pe’er,et al.  High-Energy Photon Emission in the Early Afterglow of GRBs , 2004, astro-ph/0407084.

[33]  D. Gingrich,et al.  VERY HIGH ENERGY OBSERVATIONS OF GAMMA-RAY BURSTS WITH STACEE , 2010 .

[34]  Temporal evolution of pair attenuation signatures in gamma-ray burst spectra , 2006, astro-ph/0606425.

[35]  J. A. Hinton,et al.  The status of the HESS project , 2004 .

[36]  A. Chilingarian,et al.  MAGIC upper limits on the high energy emission from GRBs , 2007, 0709.1386.

[37]  Bing Zhang,et al.  Gamma-Ray Bursts: Progress, Problems & Prospects , 2004 .

[38]  B. Dingus,et al.  A γ-ray burst with a high-energy spectral component inconsistent with the synchrotron shock model , 2003, Nature.

[39]  W. E. Harris,et al.  Photospheric radius expansion X-ray bursts as standard candles , 2002, astro-ph/0212028.

[40]  T. Piran,et al.  High-energy afterglow emission from gamma-ray bursts , 2007, 0704.2063.