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Search for Discrete X-ray Spectral Features in a Sample of Bright Gamma-ray Burst Afterglows.

DE2004833044

Publication Date	2004
Personal Author	Sako, M.
Page Count	94
Abstract	We present uniform, detailed spectral analyses of gamma-ray burst (GRB) X-ray afterglows observed with ASCA, Beppo-SAX, Chandra, and XMM-Newton, and critically evaluate the statistical significances of X-ray emission and absorption features in these spectra. The sample consists of 21 X-ray afterglow observations up to and including that of GRB040106 with spectra of sufficient statistical quality to allow meaningful line searches, chosen here somewhat arbitrarily to be detections with more than 100 total (source plus background) counts. This sample includes all nine X-ray afterglows with published claims of line detections. Moderate resolution spectra are available for 16 of the 21 sources, and for the remaining five the Chandra transmission grating spectrometers obtained high-resolution data. All of the data are available from the public archive. We test a simple hypothesis in which the observed spectra are produced by a power-law continuum model modified by photoelectric absorption by neutral material both in our Galaxy and possibly also local to the burst.
Keywords	Afterglow Cosmic gamma bursts X-ray spectra Spectral response X radiation Absorption Emission Monte carlo method Mathematical models Galaxies
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Stanford Linear Accelerator Center, CA.; California Inst. of Tech., Pasadena. Space Radiation Lab.; Department of Energy, Washington, DC.
Supplemental Notes	Prepared in cooperation with California Inst. of Tech., Pasadena. Space Radiation Lab. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200514

Search for Discrete X-ray Spectral Features in a Sample of Bright Gamma-ray Burst Afterglows.

Search for Discrete X-ray Spectral Features in a Sample of Bright Gamma-ray Burst Afterglows.
DE2004833044

Publication Date	2004
Personal Author	Sako, M.
Page Count	94
Abstract	We present uniform, detailed spectral analyses of gamma-ray burst (GRB) X-ray afterglows observed with ASCA, Beppo-SAX, Chandra, and XMM-Newton, and critically evaluate the statistical significances of X-ray emission and absorption features in these spectra. The sample consists of 21 X-ray afterglow observations up to and including that of GRB040106 with spectra of sufficient statistical quality to allow meaningful line searches, chosen here somewhat arbitrarily to be detections with more than 100 total (source plus background) counts. This sample includes all nine X-ray afterglows with published claims of line detections. Moderate resolution spectra are available for 16 of the 21 sources, and for the remaining five the Chandra transmission grating spectrometers obtained high-resolution data. All of the data are available from the public archive. We test a simple hypothesis in which the observed spectra are produced by a power-law continuum model modified by photoelectric absorption by neutral material both in our Galaxy and possibly also local to the burst.
Keywords	Afterglow Cosmic gamma bursts X-ray spectra Spectral response X radiation Absorption Emission Monte carlo method Mathematical models Galaxies
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Stanford Linear Accelerator Center, CA.; California Inst. of Tech., Pasadena. Space Radiation Lab.; Department of Energy, Washington, DC.
Supplemental Notes	Prepared in cooperation with California Inst. of Tech., Pasadena. Space Radiation Lab. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200514