HETE-2 Observations of the X-Ray Flash XRF 040916
/ Authors
M. Arimoto, N. Kawai, Motoko Suzuki, R. Sato, N. V. Pazmino, T. Shimokawabe, T. Ishimura, J. Kotoku, A. Yoshida, T. Tamagawa
and 36 more authors
Y. Shirasaki, M. Matsuoka, Y. Nakagawa, N. Ishikawa, A. Kobayashi, S. Sugita, I. Takahashi, M. Kuwahara, M. Yamauchi, K. Takagishi, I. Hatsukade, J. Atteia, A. Pelangeon, R. Vanderspek, C. Graziani, G. Prigozhin, J. Villasenor, J. Jernigan, G. Crew, K. Hurley, T. Sakamoto, G. Ricker, S. Woosley, N. Butler, A. Levine, J. Doty, T. Donaghy, D. Lamb, E. Fenimore, M. Galassi, M. Boer, J. Dezalay, J. Olive, J. Braga, R. Manchanda, G. Pizzichini
/ Abstract
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.
Journal: Publications of the Astronomical Society of Japan