The role of non-axisymmetry of magnetic flux rope in constraining solar eruptions

Whether a solar eruption is successful or failed depends on the competition between different components of the Lorentz force exerting on the flux rope that drives the eruption. The present models only consider the strapping force generated by the background magnetic field perpendicular to the flux rope and the tension force generated by the field along the flux rope. Using the observed magnetic field on the photosphere as a time-matching bottom boundary, we perform a data-driven magnetohydrodynamic simulation for the 30 January 2015 confined eruption and successfully reproduce the observed solar flare without a coronal mass ejection. Here we show a Lorentz force component, resulting from the radial magnetic field or the non-axisymmetry of the flux rope, which can essentially constrain the eruption. Our finding contributes to the solar eruption model and presents the necessity of considering the topological structure of a flux rope when studying its eruption behaviour.

FIGARO simulation: FIlaments & GAlactic RadiO simulation

We produce the first low to mid-frequency radio simulation that incorporates both traditional extragalactic radio sources as well as synchrotron cosmic web emission. The FIlaments & GAlactic RadiO (FIGARO) simulation includes 10 unique 4° × 4° fields, incorporating active galactic nucleii (AGNs), star-forming galaxies (SFGs), and synchrotron cosmic web emission out to a redshift of z = 0.8 and over the frequency range 100–1 400 MHz. To do this, the simulation brings together a recent 1003 Mpc3 magnetohydrodynamic simulation (Vazza et al. 2019, A&A, 627, A5), calibrated to match observed radio relic population statistics, alongside updated ‘T-RECS’ code for simulating extragalactic radio sources (Bonaldi et al. 2019, MNRAS, 482, 2). Uniquely, the AGNs and SFGs are populated and positioned in accordance with the underlying matter density of the cosmological simulation. In this way, the simulation provides an accurate understanding of the apparent morphology, angular scales, and brightness of the cosmic web as well as—crucially—the clustering properties of the cosmic web with respect to the embedded extragalactic radio population. We find that the synchrotron cosmic web does not closely trace the underlying mass distribution of the cosmic web, but is instead dominated by shocked shells of emission surrounding dark matter halos and resembles a large, undetected population of radio relics. We also show that, with accurate kernels, the cosmic web radio emission is clearly detectable by cross-correlation techniques and this signal is separable from the embedded extragalactic radio population. We offer the simulation as a public resource towards the development of techniques for detecting and measuring the synchrotron cosmic web.

Testing Computational Magnetohydrodynamics Algorithms with a Problem Having an Exact Solution

Представлены результаты тестирования разработанного пакета программ для численного моделирования задач магнитной гидродинамики. Программный комплекс создан с использованием технологии CUDA Fortran и ориентирован на вычислительные системы с графическими процессорами. Получено точное трехмерное решение системы уравнений магнитной гидродинамики, которое использовалось для тестирования реализованных вычислительных алгоритмов. Результаты тестовых расчетов демонстрируют корректность получаемых численных решений. The results of testing the magnetohydrodynamic simulation software package developed by the authors are presented. The software package was developed with CUDA Fortran and is intended for GPU computing systems. An exact 3D solution of the system of magnetohydrodynamic equations was obtained and applied to testing the computational algorithms. The test results demonstrate that the numerical solutions are valid.