Speaker
Takeshi Fujinuma
(Saitama University)
Description
The Wide-band All-sky Monitor (WAM) on board the X-ray astronomical satellite Suzaku consists of four sides of BGO scintillation counters within the Hard X-ray Detector. Thanks to large effective area (800 cm2 at 100 keV) and field of view of ∼ 2π st, the WAM has detected transient objects, such as Gamma-Ray Bursts (GRBs) and Solar flares, approximately 300 event per year. However, the WAM itself can not determine the position of incident photons since the WAM is a non-imaging detector. The energy response of the WAM has strong dependency on the incident angle (Terada IEEE ’07) and thus the position is required for the spectral analyses. Currently, all spectral results with WAM are obtained only by flaring events whose positions are measured by other missions. Actually, we have perfomed spectral analysis of only 10% of all detected GRBs by the WAM, which observed simultaneously with other satellite. In order to estimate locations of rest GRBs only with WAM, we performed Monte-Calro simulation using Suzaku mass model reproduced entire satellite besed on Geant4 toolkit and found out counts of the WAM in detail for each incident angle. And, we developed the method of estimating location by the WAM four sides independently. We verified our method using 32 GRBs whose locations are revealed by other satellites and found that an average of difference of azimuthal angles is approximately 7◦, except for direction of refrigerant tank which has large amount of material. Moreover, we also estimated the systematic errors in the response matrix we derived by this method using the same datasets. When spectrum fitted by Band function that model reproduce GRB spctra well, estimated systematic error of alpha, beta, Epeak, and flux are 25%, 3%, 18%, and 29% respectively. Our results show a probability that spectral analysis of new 1800 events is available.
Primary author
Takeshi Fujinuma
(Saitama University)
Co-authors
Dr
Kazutaka Yamaoka
(Nagoya University)
Prof.
Makoto Tashiro
(Saitama University)
Dr
Masanori Ohno
(Hiroshima University)
Dr
Satoshi Sugita
(Ehime University)
Dr
Tetsuya Yasuda
(Saitama University)
Dr
Yukikatsu terada
(Saitama University)
