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X-Ray Polarimetry Workshop SLAC, Stanford, California 9-11 February 2004 |
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Re-analysis of Polarization in the Gamma-ray Flux of GRB021206
Robert
Rutledge
McGill
rutledge@physics.mcgill.ca
Robert E. Rutledge (McGill) and Derek B. Fox (Caltech)
We re-examine the RHESSI data for GRB 021206 and find no signal that can be interpreted as due to polarization of the gamma-ray flux. The number of scattering events suitable for measuring polarization -- having been scattered from one detector to another, with a count produced in both -- is considerably lower than previous estimates, by a factor of 10 (830+/-150 vs. 9840+/-96). We develop and apply a polarization-detection analysis limited in sensitivity only by Poisson noise, which does not require a space-craft mass model to detect polarization, finding no signal which might be interpreted as due to polarization of GRB 021206. Separately, we reproduce the signal found previously by Coburn and Boggs (2003), and show that it is not due to polarization in the GRB flux. Due to the low signal-to-noise ratio of the RHESSI data, our Poisson noise-limited analysis results in an upper limit consistent with 100%-polarization of the gamma-ray flux from GRB 021206. No observational constraint on the intrinsic polarization of GRB 021206 can be derived from these data.
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For more information, contact
Jennifer Formichelli |
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