Spectral Cross-Calibration of the Konus-Wind, the Suzaku/WAM, and the Swift/BAT Data Using Gamma-Ray Bursts

• Published in: Publications of the Astronomical Society of Japan Vol. 63; no. 1; pp. 215 - 277
• Main Authors: Sakamoto, Takanori, Pal'SHIN, Valentin, Yamaoka, Kazutaka, Ohno, Masanori, Sato, Goro, Aptekar, Rafail, Barthelmy, Scott D., Baumgartner, Wayne H., Cummings, Jay R., Fenimore, Edward E., Frederiks, Dmitry, Gehrels, Neil, Golenetskii, Sergey, Krimm, Hans A., Markwardt, Craig B., Onda, Kaori, Palmer, David M., Parsons, Ann M., Stamatikos, Michael, Sugita, Satoshi, Tashiro, Makoto, Tueller, Jack, Ukwatta, Tilan N.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford University Press 25.02.2011
• Subjects: instrumentation: detectors; gamma rays: general; gamma-ray burst: general
• ISSN: 0004-6264; 2053-051X
• DOI: 10.1093/pasj/63.1.215

We report on the spectral cross-calibration results of the Konus-Wind, the Suzaku/WAM, and the Swift/BAT instruments using simultaneously observed gamma-ray bursts (GRBs). This is the first attempt to use simultaneously observed GRBs as a spectral calibration source to understand systematic problems among the instruments. Based on these joint spectral fits, we find that (1) although a constant factor (a normalization factor) agrees within 20% among the instruments, the BAT constant factor shows a systematically smaller value by 10%–20% compared to that of Konus-Wind, (2) there is a systematic trend that the low-energy photon index becomes steeper by 0.1–0.2 and $E_{\rm peak}$ becomes systematically higher by 10%–20% when including the BAT data in the joint fits, and (3) the high-energy photon index agrees within 0.2 among the instruments. Our results show that cross-calibration based on joint spectral analysis is an important step to understanding the instrumental effects that could be affecting the scientific results from the GRB prompt emission data.