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Testing the E(sub peak)-E(sub iso) Relation for GRBs Detected by Swift and Suzaku-WAMOne of the most prominent, yet controversial associations derived from the ensemble of prompt-phase observations of gamma-ray bursts (GRBs) is the apparent correlation in the source frame between the peak energy (E(sub peak)) of the nuF(nu) spectrum and the isotropic radiated energy, E(sub iso). Since most gamma-ray bursts (GRBs) have E(sub peak) above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, determining accurate E(sub peak) values for large numbers of Swift bursts has been difficult. However, by combining data from Swift/BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV, for bursts which are simultaneously detected ; one can accurately fit E(sub peak) and E(sub iso) and test the relationship between them for the Swift sample. Between the launch of Suzaku in July 2005 and the end of March 2009, there were 45 gamma-ray bursts (GRBs) which triggered both Swift/BAT and WAM and an additional 47 bursts which triggered Swift and were detected by WAM, but did not trigger. A BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine spectral parameters. For those bursts with spectroscopic redshifts.. we can also calculate the isotropic energy. Here we present the results of joint Swift/BAT-Suzaku/WAM spectral fits for 86 of the bursts detected by the two instruments. We show that the distribution of spectral fit parameters is consistent with distributions from earlier missions and confirm that Swift, bursts are consistent with earlier reported relationships between Epeak and isotropic energy. We show through time-resolved spectroscopy that individual burst pulses are also consistent with this relationship.
Document ID
20090023871
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Krimm, H. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Yamaoka, K. (Aoyamagakuin Univ. Kanagawa, Japan)
Sugita, S. (Aoyamagakuin Univ. Kanagawa, Japan)
Ohno, M. (Japan Aerospace Exploration Agency Kanagawa, Japan)
Sakamoto, T. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Barthelmy, S. D. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Gehrels, N. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hara, R. (Saitama Univ. Saitama, Japan)
Onda, K. (Denver Univ. Denver, CO, United States)
Sato, G. (Japan Aerospace Exploration Agency Kanagawa, Japan)
Tanaka, H. (Saitama Univ. Saitama, Japan)
Tashiro, M. (Saitama Univ. Saitama, Japan)
Yamauchi, M. (Saitama Univ. Saitama, Japan)
Norris, J. P. (Denver Univ. Denver, CO, United States)
Ohmori, N. (Saitama Univ. Saitama, Japan)
Date Acquired
August 24, 2013
Publication Date
April 29, 2009
Subject Category
Astronomy
Distribution Limits
Public
Copyright
Public Use Permitted.

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