Can a simple instrument measure polarization in gamma-ray bursts.pdfVIP

a r X i v : a s t r o - p h / 0 4 0 2 5 9 6 v 1 2 5 F e b 2 0 0 4 Can a simple instrument measure polarization in gamma-ray bursts? A. Curioni, N. Mirabal Columbia University, New York, NY, USA Abstract The recent claim of a high degree of linear polarization in the prompt gamma- ray burst (GRB) emission of GRB 021206 might have important implications for the underlying mechanism ultimately responsible for the GRB radiation. While the claim itself remains controversial, a full characterization of the GRB polarization has become a scientific imperative. A review of past and present polarimetry missions motivates a set of guidelines for future dedicated GRB polarization experiments. It is also argued that polarization in GRBs could be measured by a relatively simple instrument using readily available technology. Key words: gamma-ray, polarization PACS: 1 Introduction The nature of the prompt GRB emission remains one of the outstanding as- trophysical mysteries of the past 35 years [1]. The central problem concerns the lack of a proven mechanism that can both extract energy from a col- lapsing GRB progenitor, and generate prime conditions for the production of relativistic outflows [2]. Three models have emerged as the leading candidates for explanation of the prompt GRB emission. In conventional hydrodynamic models, internal or external shock fronts accelerate particles that radiate high- energy photons [3,4,5,6]. In the case of electromagnetic models, the GRB pro- genitor loses much of its spin in the form of an electromagnetically dominated outflow that can extend all the way out to the γ-ray emission region [7]. The cannonball model relies on inverse Compton scattering of photons to GRB Email addresses: curioni@ (A. Curioni), abulafia@ (N. Mirabal). Preprint submitted to Elsevier Science 2 February 2008 energies [9]. Although various numerical simulations have been successful in reproducing the complex structure observed in GRB light curves [10,11], the observ