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首页> 外文期刊>Astronomy and astrophysics >Modelling shock drift acceleration of electrons at the reconnection outflow termination shock in solar flares - Observational constraints and parametric study
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Modelling shock drift acceleration of electrons at the reconnection outflow termination shock in solar flares - Observational constraints and parametric study

机译：太阳耀斑中重新连接流出终止冲击时电子的冲击漂移加速度建模-观测约束和参数研究

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Context. The acceleration of electrons to nonthermal energies in solar flares is one of the main unsolved questions in solar physics. One possibility for producing these energetic electrons is acceleration at the reconnection outflow termination shock(TS). Aims. By comparing theoretical results with observations of nonthermal electrons, we determine whether shock drift acceleration(SDA) at the TS is a viable electron acceleration mechanism. Methods. We used radio observations to constrain the characteristics of the TS, and hard X-ray observations provided by RHESSI, INTEGRAL, and HXRS to obtain the characteristics of the injected electrons. Invoking relativistic shock-drift acceleration at the TS, we calculated electron flux spectra, which are then compared with the corresponding observational results from RHESSI. A parametric study of the model allows us to answer the question under which conditions the TS is a viable electron accelerator. Results. SDA at the TS is able to reproduce the required fluxes and kinetic power of nonthermal electrons in solar flares as long as there is significant heating of the outflow jet and a sufficiently large shock area. A prediction of the model is that the flux and power of injected electrons is higher than the values that are usually given by fitting observed spectra, since the low-energy cutoff is generally below 10keV. The synthetic spectra are consistent with the observed spectral indices up to 100keV. Beyond that, they soften too quickly. Possibly this is because we have not yet considered various additional effects, such as multiple reflections at the shock or some form of preacceleration. The observed relation between electron flux and spectral index is reproduced by the model, as well as the temporal evolution of the energetic electrons. We conclude that SDA at the TS is a viable electron acceleration mechanism that deserves further study. Key words: Sun: flares - Sun: corona - Sun: radio radiation - Sun: X-rays, gamma rays - shock waves - acceleration of particles
机译：上下文。太阳耀斑中电子向非热能的加速是太阳物理学中尚未解决的主要问题之一。产生这些高能电子的一种可能性是在重新连接流出终止冲击（TS）处加速。目的通过将理论结果与非热电子的观察结果进行比较，我们确定TS处的激波漂移加速（SDA）是否是可行的电子加速机制。方法。我们使用无线电观测来约束TS的特性，并使用RHESSI，INTEGRAL和HXRS提供的硬X射线观测来获得注入电子的特性。在TS处调用相对论性的冲击加速度，我们计算了电子通量谱，然后将其与RHESSI的相应观测结果进行比较。对模型的参数研究使我们能够回答在什么条件下TS是可行的电子促进剂。结果。只要流出的射流有足够的热量和足够大的冲击面积，TS上的SDA就能复制太阳耀斑中非热电子所需的通量和动能。该模型的预测是，注入的电子的通量和功率高于通常通过拟合观察到的光谱所给出的值，因为低能量截止值通常低于10keV。合成光谱与观察到的高达100keV的光谱指数一致。除此之外，它们变得太软。这可能是因为我们尚未考虑各种其他影响，例如冲击时的多次反射或某种形式的预加速。该模型再现了观察到的电子通量和光谱指数之间的关系，以及高能电子的时间演化。我们得出的结论是，TS处的SDA是可行的电子加速机制，值得进一步研究。关键词：太阳：耀斑-太阳：日冕-太阳：无线电辐射-太阳：X射线，伽马射线-冲击波-粒子加速

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