Global Characteristics of X‐Ray Flashes and X‐Ray–Rich Gamma‐Ray Bursts Observed by<i>HETE</i>‐<i>2</i>
T. SakamotoDepartment of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, JapanD. Q. LambDepartment of Astronomy and Astrophysics, University of Chicago, Chicago, IL, 60637N. KawaiDepartment of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, JapanA. YoshidaDepartment of Physics, Aoyama Gakuin University, Chitosedai 6-16-1, Setagaya-ku, Tokyo 157-8572, JapanC. GrazianiDepartment of Astronomy and Astrophysics, University of Chicago, Chicago, IL, 60637E. E. FenimoreLos Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545T. DonaghyDepartment of Astronomy and Astrophysics, University of Chicago, Chicago, IL, 60637M. MatsuokaM. SuzukiDepartment of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, JapanG. RickerCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139J. L. AtteiaLaboratoire d’Astrophysique, Observatoire Midi-Pyreńeés, 14 Avenue Edouard Belin, 31400 Toulouse, FranceY. ShirasakiNational Astronomical Observatory, Osawa 2-21-1, Mitaka, Tokyo 181-8588, JapanT. TamagawaRIKEN (Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, JapanK. ToriiDepartment of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, JapanM. GalassiLos Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545J. DotyCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139R. VanderspekCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139G. CrewCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139J. VillaseñorCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139N. ButlerCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139G. PrigozhinCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139J. G. JerniganSpace Sciences Laboratory, University of California, Berkeley, CA 94720-7450C. BarraudLaboratoire d’Astrophysique, Observatoire Midi-Pyreńeés, 14 Avenue Edouard Belin, 31400 Toulouse, FranceM. BoërCentre d’Etude Spatiale des Rayonnements, CNRS/UPS, B.P. 4346, 31028 Toulouse Cedex 4, FranceJ. P. DezalayCentre d’Etude Spatiale des Rayonnements, CNRS/UPS, B.P. 4346, 31028 Toulouse Cedex 4, FranceJ. F. OliveCentre d’Etude Spatiale des Rayonnements, CNRS/UPS, B.P. 4346, 31028 Toulouse Cedex 4, FranceK. HurleySpace Sciences Laboratory, University of California, Berkeley, CA 94720-7450Alan M. LevineCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139G. MonnellyCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139F. MartelCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139E. MorganCenter for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139S. E. WoosleyDepartment of Astronomy and Astrophysics, 477 Clark Kerr Hall, University of California, Santa Cruz, CA 95064T. L. ClineNASA Goddard Space Flight Center, Greenbelt, MD, 20771J. BragaInstituto Nacional de Pesquisas Espaciais, Avenida Dos Astronautas 1758, Saõ Josédos Campos 12227-010, BrazilR. ManchandaDepartment of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, IndiaG. PizzichiniINAF/IASF Sezione di Bologna, via Gobetti 101, 40129 Bologna, ItalyK. TakagishiFaculty of Engineering, Miyazaki University, Gakuen Kibanadai Nishi, Miyazaki 889-2192, JapanM. YamauchiFaculty of Engineering, Miyazaki University, Gakuen Kibanadai Nishi, Miyazaki 889-2192, Japan
2005en
ABI
Abstract
We describe and discuss the global properties of 45 gamma-ray bursts (GRBs) observed by HETE-2 during the first 3 years of its mission, focusing on the properties of X-ray flashes (XRFs) and X-ray-rich GRBs (XRRs). We find that the numbers of XRFs, XRRs, and GRBs are comparable, and that the durations and the sky distributions of XRFs and XRRs are similar to those of GRBs. We also find that the spectral properties of XRFs and XRRs are similar to those of GRBs, except that the values of the peak energy E of the burst spectrum in νFν, the peak energy flux Fpeak, and the energy fluence SE of XRFs are much smaller (and those of XRRs are smaller) than those of GRBs. Finally, we find that the distributions of all three kinds of bursts form a continuum in the [SE(2-30 keV), SE(30-400) keV] plane, the [SE(2-400 keV), Epeak] plane, and the [Fpeak(50-300 keV), Epeak] plane. These results provide strong evidence that all three kinds of bursts arise from the same phenomenon.
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