2005/05/05 by D. R. Willis, E. J. Barlow, A. J. Bird +10 · 3 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Atmosphere (unit) #Fermi Gamma-ray Space Telescope #Flux (metallurgy) #Gamma ray #Gamma-ray burst #Gamma-ray bursts and supernovae #Optics #Physics #Polarimetry #Scattering #Sky #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1051/0004-6361:20052693
10 pages, 12 figures, Accepted, A&A
arxiv created 2005/05/05 · openalex publication_date 2005/07/22 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
The true nature of the progenitor to GRBs remains elusive; one characteristic that would constrain our understanding of the GRB mechanism considerably is gamma-ray polarimetry measurements of the initial burst flux. We present a method that interprets the prompt GRB flux as it Compton scatters off the Earth's atmosphere, based on detailed modelling of both the Earth's atmosphere and the orbiting detectors. The BATSE mission aboard the CGRO monitored the whole sky in the 20 keV–1 MeV energy band continuously from April 1991 until June 2000. We present the BATSE Albedo Polarimetry System (BAPS), and show that GRB 930131 and GRB 960924 provide evidence of polarisation in their prompt flux that is consistent with degrees of polarisation of % and % respectively. While the evidence of polarisation is strong, the method is unable to strongly constrain the degree of polarisation beyond a systematics based estimation. Hence the implications on GRB theory are unclear, and further measurements essential.