2022年3月28日亚太赫兹耀斑的脉冲前与脉冲阶段
Pre-impulsive and Impulsive Phases of the Sub-Terahertz Flare of March 28, 2022
AI总结：
本研究针对2022年3月28日M4.0级太阳耀斑，结合多波段观测分析亚太赫兹辐射的起源，发现热自由-自由机制无法解释观测流量，排除了日冕加速电子和环顶热流的加热作用，探讨了脉冲前色球加热的可能机制。
摘要：
太阳射电频谱的特性以及耀斑辐射的时间剖面表明，观测到的亚太赫兹（sub-THz）分量具有热性质，该分量表现为100-1000 GHz频率范围内射电辐射的增强。亚太赫兹耀斑的起始时间可比脉冲阶段提前数分钟。然而，脉冲前和脉冲阶段亚太赫兹辐射的起源仍不明确。本工作致力于利用鲍曼莫斯科国立技术大学RT-7.5射电望远镜在93 GHz频段的观测，对2022年3月28日观测到的M4.0级X射线太阳耀斑开展详细分析。我们结合了X射线（GOES、GBM/Fermi）、极紫外（AIA/SDO）和微波波段的多波长太阳观测数据。通过基于AIA/SDO数据求解反问题，确定了产生极紫外辐射的微分发射量（DEM）。利用该DEM并假设脉冲前和脉冲阶段的辐射机制为热自由-自由发射，我们计算了耀斑源日冕等离子体的毫米波辐射流量，结果显示其远小于观测值。我们得出结论：日冕中加速的电子以及来自日冕环顶部的热流都无法为位于过渡区和色球上层的亚太赫兹辐射源提供加热。本文还讨论了太阳耀斑脉冲前阶段色球加热的一种可能起源。
英文摘要：
Properties of the solar radio spectrum, as well as the temporal profiles of flare emission, indicate the thermal nature of the sub-terahertz (sub-THz) component observed as the growth of radio emission in the frequency range of 100-1000 GHz. The sub-THz flare onset can be ahead of the impulsive phase for several minutes. However, the origin of the pre-impulsive and impulsive sub-THz emission remains unclear. The present work is devoted to a detailed analysis of the M4.0 X-class solar flare observed on March 28, 2022 with the Bauman Moscow State Technical University Radio Telescope RT-7.5 at 93 GHz. We supply these data with multiwavelength solar observations in the X-ray (GOES, GBM/Fermi), extreme ultraviolet (AIA/SDO), and microwave ranges. The differential emission measure (DEM) responsible for EUV emission is determined by solving the inverse problem based on the AIA/SDO data. Using the DEM and assuming a thermal free-free emission mechanism in pre-impulsive and impulsive phases, we calculated the millimeter emission flux of coronal plasma of the flare source, which turned out to be much smaller than the observed values. We concluded that electrons accelerated in the corona and heat fluxes from the coronal loop top cannot be responsible for heating the sub-THz emission source located in the transition region and upper chromosphere. A possible origin of chromospheric heating in the pre-impulsive phase of the solar flare is discussed.
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