http://arxiv.org/abs/1506.01251
Twisted magnetic fields should be ubiquitous in the solar corona. The magnetic energy contained in such twisted fields can be released during solar flares and other explosive phenomena. Reconnection in helical magnetic coronal loops results in plasma heating and particle acceleration distributed within a large volume, including the lower coronal and chromospheric sections of the loops, and can be a viable alternative to the standard flare model, where particles are accelerated only in a small volume located in the upper corona. The goal of this study is to investigate the observational signatures of plasma heating and particle acceleration in kink-unstable twisted coronal loops using combination of MHD simulations and test-particle methods. The simulations describe the development of kink instability and magnetic reconnection in twisted coronal loops using resistive compressible MHD, and incorporate atmospheric stratification and large-scale loop curvature. The resulting distributions of hot plasma let us estimate thermal X-ray emission intensities. Test-particle trajectories combined with the density distributions let us deduce synthetic hard X-ray bremsstrahlung intensities. Our simulations emphasise that the geometry of the emission patterns produced in flaring twisted coronal loops can differ from the actual geometry of the underlying magnetic fields. The twist angles revealed by the soft X-ray thermal emission (SXR) are lower than the field-line twist present at the onset of the kink-instability. Hard X-ray (HXR) emission due to the collisions of energetic electrons with the stratified background are concentrated at the loop foot-points, even though the electrons are accelerated everywhere within the coronal volume of the loop. The HXR light-curve are approximately proportional to the temporal derivative of the SXR light-curve.
R. Pinto, M. Gordovskyy, P. Browning, et. al.
Thu, 4 Jun 15
31/60
Comments: (submitted to A&A)
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