arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.06073astro-ph.SR
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与日冕物质抛射相关的太阳射电爆发的成像光谱

Imaging Spectroscopy of CME-Associated Solar Radio Bursts

Sherry Chhabra, Dale E. Gary, Gregg Hallinan, Marin M. Anderson, Bin Chen, Lincoln J. Greenhill, Danny C. Price

摘要:

我们目前的第一个太阳射电事件与欧文斯谷射电天文台长波长阵列(OVRO-LWA)在米波观测的结果。我们研究了一个复杂的事件,包括多个无线电源/爆发与快速日冕物质抛射(CME)和M2.1 GOES软X射线耀斑从2015年9月20日。用9秒的图像分析了120分钟内的事件,并观测到距离为$\approx3.5\,R_\odot$的太阳辐射,瞬时带宽在40- 70 MHz的频率范围内覆盖22 MHz。我们提出了我们的结果,从调查的无线电事件,特别是集中在一个爆发源,表现出向外的运动,我们归类为一个移动的IV型爆发。我们在多个频率下对事件进行成像,并使用源质心来获得向外运动的速度。与LASCO(C2)日冕物质抛射白光中CME观测的时空比较表明,向外运动与CME的核心有关。通过对日冕物质抛射体进行梯度圆柱壳(GCS)重建,我们约束了体积中的密度。从密度估计获得的电子等离子体频率不允许我们完全驳回等离子体发射的基本机制。然而,基于源的高度和平滑的发射频率和时间,我们认为,回旋同步加速器是更合理的机制。我们使用回旋同步光谱拟合技术来估计不断变化的物理条件,在向外运动的爆发源。

英文摘要:

We present first results of a solar radio event observed with the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) at metric wavelengths. We examine a complex event consisting of multiple radio sources/bursts associated with a fast coronal mass ejection (CME) and an M2.1 GOES soft X-ray flare from 2015 September 20. Images of 9--s cadence are used to analyze the event over a 120-minute period, and solar emission is observed out to a distance of $\approx3.5\,R_\odot$, with an instantaneous bandwidth covering 22~MHz within the frequency range of 40--70~MHz. We present our results from the investigation of the radio event, focusing particularly on one burst source that exhibits outward motion, which we classify as a moving type IV burst. We image the event at multiple frequencies and use the source centroids to obtain the velocity for the outward motion. Spatial and temporal comparison with observations of the CME in white light from the LASCO(C2) coronagraph, indicates an association of the outward motion with the core of the CME. By performing graduated-cylindrical-shell (GCS) reconstruction of the CME, we constrain the density in the volume. The electron plasma frequency obtained from the density estimates do not allow us to completely dismiss plasma emission as the underlying mechanism. However, based on source height and smoothness of the emission in frequency and time, we argue that gyrosynchrotron is the more plausible mechanism. We use gyrosynchrotron spectral fitting techniques to estimate the evolving physical conditions during the outward motion of this burst source.

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