Abstract

Using the RT-32 radio telescope of the “Svetloe” IAA RAS observatory in 2017–2018, the flux density measurements of the combined (composite) supernova remnant (SNR) 3С396 (G39.2-0.3) at frequencies of 4840 and 8450 MHz are presented. The data obtained demonstrate source variability. Published data were used to determine the 3C396 flux density in 1962–2008 based on a comparison of the intensities of 3C396 and standard sources. To reduce all the data to a unified system, we used the “artificial moon” (AM) flux scale. A refined spectrum of SNR 3C396 was obtained, which is approximated as the sum of two power-law components with spectral indices α₁ = 0.5 and α₂ = 0.157. It is assumed that the components of the spectrum are due to emission from the shell and plerion, respectively. The plerion contribution to the SNR’s total flux is estimated: at a wavelength λ = 21 cm, it is close to 30%. Earlier, the contribution estimate was based on X-ray data and did not exceed 4%. The above discrepancy is eliminated if there is a kink in the spectrum of the plerion, similarly to spectra 3C58 and G21.5-0.9. The data obtained during measurements with RT-32 and based on published works show changes in the source flux density on different time scales, from short time intervals (t_min < 0.5 years) or more. The localization and possible causes of detected variability are discussed.

中文翻译：

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超新星残余3C396（G39.2-0.3）的无线电发射

摘要

使用2017-2018年“ Svetloe” IAA RAS天文台的RT-32射电望远镜，在4840和8450 MHz频率下，对组合（复合）超新星残留（SNR）3С396（G39.2-0.3）的通量密度测量被提出。获得的数据证明了来源的可变性。基于3C396和标准光源强度的比较，已发布的数据用于确定1962–2008年的3C396通量密度。为了将所有数据减少到一个统一的系统，我们使用了“人造月球”（AM）通量表。SNR 3C396的精制，所得光谱，其近似为2的幂律组件与和光谱指数α ₁ = 0.5，α ₂= 0.157。假定光谱的分量分别是由于壳和pl的发射引起的。估计pl对SNR总通量的贡献：在波长λ= 21 cm时，接近30％。早些时候，贡献估算是基于X射线数据，并且不超过4％。如果在pl虫的光谱中有一个纽结，则可以消除上述差异，类似于光谱3C58和G21.5-0.9。在RT-32的测量过程中并基于已发表的工作获得的数据显示，在较短的时间间隔（t _min <0.5年）或更长时间内，源通量密度在不同的时间尺度上会发生变化。讨论了定位和检测到的变化的可能原因。