A Deep, High-Resolution Survey at 74 MHz
A Deep, High-Resolution Survey at 74 MHz
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74 MHz 的深度、高分辨率测量
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
T. Lazio
中科院分区：
文献类型：
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作者：
A. Cohen;A. Cohen;H. Röttgering;Matt J. Jarvis;N. Kassim;T. Lazio
我们提出了一个74 MHz的调查165 deg 2区域位于银河系北极附近。该测量具有分辨率（25″ FWHM）和灵敏度（σ低至24 mJy beam-1）的前所未有的组合。我们在该区域检测到949个5 σ水平的源，足以开始探索74 MHz源群的性质。我们提出了差分源计数，光谱指数测量，并确定从同行的高分辨率FIRST 1.4 GHz的调查的大小分布。我们发现一个趋势陡峭的光谱指数为更明亮的来源。此外，频谱指数和中值源大小之间存在明显的相关性，平均而言，平坦频谱源要小得多。超陡谱天体（α ≤ -1.2; Sνα）被识别，我们提出了高分辨率的VLA跟踪观测这些源，在这样一个低的频率，确定是高红移射电星系的优秀候选人。
We present a 74 MHz survey of a 165 deg2 region located near the north Galactic pole. This survey has an unprecedented combination of both resolution (25″ FWHM) and sensitivity (σ as low as 24 mJy beam-1). We detect 949 sources at the 5 σ level in this region, enough to begin exploring the nature of the 74 MHz source population. We present differential source counts, spectral index measurements, and the size distribution as determined from counterparts in the high-resolution FIRST 1.4 GHz survey. We find a trend of steeper spectral indices for the brighter sources. Further, there is a clear correlation between spectral index and median source size, with the flat spectrum sources being much smaller on average. Ultra-steep spectrum objects (α ≤ -1.2; Sν ∝ να) are identified, and we present high-resolution VLA follow-up observations of these sources which, identified at such a low frequency, are excellent candidates for high-redshift radio galaxies.