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arXiv · 1808.05384

Science prospects for SPHiNX - a small satellite GRB polarimetry mission

M. Pearce·L. Eliasson·N. Kumar Iyer·M. Kiss·R. Kushwah·J. Larsson·C. Lundman·V. Mikhalev·F. Ryde·T. -A. Stana·H. Takahashi·F. Xie
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Abstract

Gamma-ray bursts (GRBs) are exceptionally bright electromagnetic events occurring daily on the sky. The prompt emission is dominated by X-/$\gamma$-rays. Since their discovery over 50 years ago, GRBs are primarily studied through spectral and temporal measurements. The properties of the emission jets and underlying processes are not well understood. A promising way forward is the development of missions capable of characterising the linear polarisation of the high-energy emission. For this reason, the SPHiNX mission has been developed for a small-satellite platform. The polarisation properties of incident high-energy radiation (50-600 keV) are determined by reconstructing Compton scattering interactions in a segmented array of plastic and Gd$_3$Al$_2$Ga$_3$O$_{12}$(Ce) (GAGG(Ce)) scintillators. During a two-year mission, $\sim$200 GRBs will be observed, with $\sim$50 yielding measurements where the polarisation fraction is determined with a relative error $\leq$10%. This is a significant improvement compared to contemporary missions. This performance, combined with the ability to reconstruct GRB localisation and spectral properties, will allow discrimination between leading classes of emission models.

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M. Pearce, L. Eliasson, N. Kumar Iyer, M. Kiss, R. Kushwah, J. Larsson, C. Lundman, V. Mikhalev, F. Ryde, T. -A. Stana, H. Takahashi, F. Xie. 2018-08-16. Science prospects for SPHiNX - a small satellite GRB polarimetry mission. https://doi.org/10.1016/j.astropartphys.2018.08.007

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