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.

中文翻译：

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使用 OVRO-LWA 对 CME 相关太阳射电暴的成像光谱

我们展示了欧文斯谷射电天文台长波长阵列 (OVRO-LWA) 在公制波长下观测到的太阳射电事件的第一个结果。我们检查了一个复杂事件，该事件由与快速日冕物质抛射 (CME) 和 M2.1 GOES 软 X 射线耀斑相关的多个射电源/爆发组成，从 2015 年 9 月 20 日开始。9-s 节奏的图像用于分析事件在 120 分钟的时间内，太阳辐射被观测到 $\approx3.5\,R_\odot$ 的距离，在 40--70~MHz 的频率范围内，瞬时带宽覆盖 22~MHz。我们展示了对无线电事件的调查结果，特别关注一个表现出向外运动的爆发源，我们将其归类为移动的 IV 型爆发。我们以多个频率对事件进行成像，并使用源质心来获得向外运动的速度。与 LASCO(C2) 日冕仪在白光下观察 CME 的时空比较表明向外运动与 CME 的核心有关。通过对 CME 进行分级圆柱壳 (GCS) 重建，我们限制了体积中的密度。从密度估计中获得的电子等离子体频率不允许我们完全排除等离子体发射作为潜在机制。然而，基于源高度和发射在频率和时间上的平滑度，我们认为陀螺同步加速器是更合理的机制。我们使用陀螺同步加速器光谱拟合技术来估计此爆发源向外运动期间不断变化的物理条件。