Abstract

Based on the spatial correlation between the distributions of diffuse ionized gas (DIG) and the HII regions in the Galaxy and using observations of the Galactic background in the H166α line found in literature, we investigated the strong inhomogeneity of the DIG in the direction of longitude 33.5° near the Galaxy plane, where objects located at close angular distances from each other have very different observable parameters due to the DIG effect. We argued the absence of a spectrum cut-off at a frequency of 30.9 MHz for the supernova remnant Kes 79 (G33.6+0.1) by the presence of an insignificant amount of ionized gas between the SNR and the observer. The large value of the pulse broadening of the pulsar B1849+00 (τ_psr = 0.86 s at 1 GHz) located at an angular distance of 10\(' \) from the center of the Kes 79 is explained by two factors. Firstly, the HII region (G33.46+0.06) is located in the direction of the pulsar with an emission measure of about 2900 pc/cm⁶, which contributes less than 32% to the dispersion measure of the pulsar and provides about 50% of the pulsar pulse broadening, despite the fact that the emission measure of ionized gas located between the observer and the pulsar, is ≈6150 pc/cm⁶. Secondly, the largest contribution to the broadening of its pulses comes from an ionized gas located approximately halfway between the pulsar and the observer, which is consistent with the scattering theory. The supernova remnant Kes 79, which is closer to the observer than the pulsar B1849+00, does not significantly affect the radiation scattering from the pulsar and the compact extragalactic source B1849+005. The distance to the pulsar B1849+00 was found to be in the range from 9.8 to 11.5 kpc.

中文翻译：

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超新星残余Kes 79和Pulsar B1849 + 00方向的扩散电离气体

摘要

基于银河中弥散离子化气体（DIG）分布与HII区域之间的空间相关性，并利用文献中H166α线的银河本底观测，我们研究了DIG在经度方向上的强不均匀性在银河平面附近的33.5°处，由于DIG效应，彼此之间相距近角的物体具有可观察到的非常不同的参数。我们认为，由于SNR和观测者之间存在少量的电离气体，对于超新星残留的Kes 79（G33.6 + 0.1）在30.9 MHz的频率处没有频谱截止。脉冲星的脉冲展宽的大的值B1849 + 00（τ _PSR 位于以10的角度距离= 0.86 s的1千兆赫）\（” \）从Kes 79的中心开始的解释有两个因素。首先，HII区域（G33.46 + 0.06）位于脉冲星方向，发射量约为2900 pc / cm ⁶，这对脉冲星的色散量贡献不到32％，并且提供了约50％尽管位于观察者和脉冲星之间的电离气体的发射量度为≈6150pc / cm ⁶。其次，对其脉冲展宽的最大贡献来自位于脉冲星和观测者之间大约一半位置的电离气体，这与散射理论是一致的。比脉冲星B1849 + 00更靠近观察者的超新星遗迹Kes 79不会显着影响来自脉冲星和紧凑型河外源B1849 + 005的辐射散射。到脉冲星B1849 + 00的距离为9.8至11.5 kpc。