A 21 cm SPECTRAL AND CONTINUUM STUDY OF IC 443 USING THE VERY LARGE ARRAY AND THE ARECIBO TELESCOPE
A 21 cm SPECTRAL AND CONTINUUM STUDY OF IC 443 USING THE VERY LARGE ARRAY AND THE ARECIBO TELESCOPE
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DOI：
10.1088/0004-6256/135/3/796
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发表时间：
2008-03
期刊：
影响因子：
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通讯作者：
Jaejoon Lee;B. Koo;M. Yun;S. Stanimirović;C. Heiles;M. Heyer
中科院分区：
文献类型：
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作者：
Jaejoon Lee;B. Koo;M. Yun;S. Stanimirović;C. Heiles;M. Heyer
我们报告21厘米光谱线和连续观测银河系超新星遗迹IC 443使用甚大阵（VLA）和阿雷西博望远镜。通过结合VLA和Arecibo数据（两者都覆盖了IC 443的全部范围），我们在从1040 ″到101 °的连续角标度范围内实现了灵敏度和角分辨率的前所未有的组合。我们的新射电观测不仅揭示了IC 443以前未知的特征，而且更清楚地显示了残骸的细节。IC 443的射电形态由两个几乎同心的壳层组成。我们的21厘米射电连续谱数据表明，这两个壳层有明显不同的径向强度分布。这种形态支持这样的假设，即西部壳是残骸进入稀薄介质的一部分。我们建立了一个解释这次爆发的动力学模型，估计其残留年龄为1.2 × 104年。遗迹的东南边界显示出有趣的特征，这是我们第一次观察到的：一个微弱的射电连续晕和许多“毛刺”。这些特征主要出现在IC 443与另一个残骸G189.6+3.3重叠的区域。这些特征很可能源自IC 443与周围介质的相互作用。与IC 443相关的H i辐射出现在−100 km s−1和50 km s−1之间的速度范围内。最强的吸收出现在vLSR <$−5 km s−1附近，这对应于IC 443的系统速度。我们确定了一个广泛的，延长的车道H i气体系统速度附近的震前气体在南部的残余。大部分的冲击氢气体位于沿着南部超新星遗迹（SNR）的边界，是蓝移。利用模板HCO+（1-0）谱，我们得到了受冲击的H i气体的精确质量，为493 ± 56 M.我们的高分辨率H i数据使我们能够将东北地区的冲击H i分解为几个与辐射细丝在位置和速度上都有很好相关的平行结构。这代表了第一次明确检测到的重组H i在原子冲击。细丝的特征与辐射信号来自密集团块的团块激波模型不一致。相反，我们认为激波是通过nH <$10 cm−3的均匀介质传播的。
We report 21 cm spectral-line and continuum observations of the Galactic supernova remnant IC 443 using the Very Large Array (VLA) and the Arecibo telescope. By combining the VLA and Arecibo data, both covering the full extent of IC 443, we have achieved an unprecedented combination of sensitivity and angular resolution, over the continuous range of angular scales from ∼40″ to ∼1°. Our new radio observations not only reveal previously unknown features of IC 443 but also show the details of the remnant more clearly. The radio morphology of IC 443 consists of two nearly concentric shells. Our 21 cm radio continuum data show that the two shells have distinctly different radial intensity distributions. This morphology supports the scenario whereby the western shell is a breakout portion of the remnant into a rarefied medium. We have developed a dynamical model accounting for the breakout, which provides an estimate for the remnant age of ∼2 × 104 yr. The southeastern boundary of the remnant shows interesting features, seen in our observations for the first time: a faint radio continuum halo and numerous “spurs.” These features are mainly found in the region where IC 443 overlaps with another remnant, G189.6+3.3. These features most likely originate from the interactions of IC 443 with the surrounding medium. The H i emission associated with IC 443 appears over the velocity range between −100 km s−1 and 50 km s−1. The strongest absorption is seen around vLSR ∼ −5 km s−1, which corresponds to the systemic velocity of IC 443. We identify a broad, extended lane of H i gas near the systemic velocity as preshock gas in the southern part of the remnant. Most of the shocked H i gas is located along the southern supernova remnant (SNR) boundary and is blueshifted. We derive an accurate mass of the shocked H i gas using template HCO+ (1-0) spectra, which is 493 ± 56 M☉. Our high-resolution H i data enable us to resolve the shocked H i in the northeastern region into a few filamentary structures, which are well correlated with radiative filaments, in both position and velocity. This represents the first unambiguous detection of the recombined H i in an atomic shock. The characteristics of the filaments are not consistent with a clumpy shock model where the radiative signature is from dense clumps. Instead we propose that the shock has been propagating through a uniform medium of nH∼ 10 cm−3.