HETE-2 Observations of the X-Ray Flash XRF 040916

Makoto Arimoto , Nobuyuki Kawai , Motoko Suzuki (1, 2) , Rie Sato (3) , Nicolas Vasquez Pazmino , Takashi Shimokawabe , Takuto Ishimura , Jun'Ichi Kotoku , Atsumasa Yoshida (4) , Toru Tamagawa , Yuji Shirasaki , Masaru Matsuoka , Yujin Nakagawa , Nobuyuki Ishikawa (5, 5) , Akina Kobayashi (6, 7) , Satoshi Sugita , Ichiro Takahashi , Makoto Kuwahara , Makoto Yamauchi , Kunio Takagishi , Isamu Hatsukade (8) , Jean-Luc Atteia (9) , Alexandre Pelangeon (10) , Roland Vanderspek , Carlo Graziani , Gregory Prigozhin , Joel Villasenor , J. Garrett Jernigan , Geoffrey B. Crew , Kevin Hurley , Takanori Sakamoto , George R. Ricker (11) , Stanford E. Woosley , Nat Butler , Al Levine (12) , John P. Doty , Timothy Q. Donaghy , Donald Q. Lamb (13) , Edward E. Fenimore , Mark Galassi (14) , Michel Boer (15, 16) , Jean-Pascal Dezalay (15) , Jean-François Olive (15, 17) , Joao Braga (18) , Ravi Manchanda (19) , Graziella Pizzichini

1 Department of Physics
2 Botanical Garden, Graduate School of Science
3 Department of Electrical Engineering
4 Chercheur indépendant
5 JAEA - Japan Atomic Energy Agency [Ibaraki]
6 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
7 NIHON UNIVERSITY - Department of Humanities and Sciences
8 Faculty of Engineering
9 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
10 LATT - Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées
11 CSR - Center for Space Research [Cambridge]
12 IGM - Institut de génétique et microbiologie [Orsay]
13 Department of Astronomy and Astrophysics [Chicago]
14 LANL - Los Alamos National Laboratory
15 CESR - Centre d'étude spatiale des rayonnements
16 OHP - Observatoire de Haute-Provence
17 UMS 831 - Services communs OMP
18 LA - Laboratoire d'Anthropobiologie
19 Institute for Plasma Research [Gandhinagar]

A long X-ray flash was detected and localized by instruments aboard the High Energy Transient Explorer II (HETE-2) at 00:03:30 UT on 2004 September 16. The position was reported to the GRB Coordinates Network (GCN) approximately 2 hours after the burst. This burst consisted of two peaks separated by ? 200 s, with durations of about 110 s and 60 s. We analyzed the energy spectra of the 1st and 2nd peaks observed with the Wide Field X-Ray Monitor (WXM) and the French Gamma Telescope (FREGATE). We discuss the origin of the 2nd peak in terms of the flux variabilities and timescales. We find that it is most likely to be part of prompt emission, and is explained by a long-acting engine model. This feature is similar to some bright X-ray flares detected in the early afterglow phase of bursts observed by the Swift satellite.

Mots clés: gamma-rays: bursts; X-rays: bursts; X-rays: individual (XRF 040916)

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Makoto Arimoto, Nobuyuki Kawai, Motoko Suzuki, Rie Sato, Nicolas Vasquez Pazmino, et al.. HETE-2 Observations of the X-Ray Flash XRF 040916. Publications of the Astronomical Society of Japan, 2007, 59, pp.695-702. ⟨hal-00286251⟩