在四个不规则星系中寻找射电超新星遗迹
A Search for Radio Supernova Remnants in Four Irregular Galaxies
摘要：
利用深（1 sigma ~ 20 microJy）、高分辨率（~20 pc）的VLA连续谱数据（20、6和3.6 cm），对附近4个不规则星系进行了射电超新星遗迹（SNR）观测。我们确定这些星系中的离散源，并使用射电光谱指数和H α图像将它们归类为SNR，H II区域或背景射电星系。我们的分类与文献大体一致。我们总共确定了43个SNR候选者：23个在NGC 1569中，7个在NGC 4214中，5个在NGC 2366中，8个在NGC 4449中。只有一个SNR--NGC 4449中经过充分研究的物体J1228+441--在20厘米处比Cas A更明亮。通过比较总的热通量密度在每个星系的H II区域的本地化，我们得出结论，一个显着的部分必须在一个扩散组件或低光度H II区域。
英文摘要：
We survey four nearby irregular galaxies for radio supernova remnants (SNRs) using deep (1 sigma ~ 20 microJy), high resolution (~20 pc) VLA continuum data at 20, 6, and 3.6 cm. We identify discrete sources in these galaxies and use radio spectral indices and H alpha images to categorize them as SNRs, H II regions, or background radio galaxies. Our classifications are generally in good agreement agreement with the literature. We identify a total of 43 SNR candidates: 23 in NGC 1569, 7 in NGC 4214, 5 in NGC 2366, and 8 in NGC 4449. Only one SNR--the well-studied object J1228+441 in NGC 4449--is more luminous at 20 cm than Cas A. By comparing the total thermal flux density in each galaxy to that localized in H II regions, we conclude that a significant fraction must be in a diffuse component or in low-luminosity H II regions.
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