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arXiv 1012.3659astro-ph.CO
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15.7 GHz射电源的10 C测量:II - First结果

10C Survey of Radio Sources at 15.7 GHz: II - First Results

Matthew L. Davies, Thomas M. O. Franzen, Elizabeth M. Waldram, Keith J. B. Grainge, Michael P. Hobson, Natasha Hurley-Walker, Anthony Lasenby, Malak Olamaie, Gu… 展开作者

Matthew L. Davies, Thomas M. O. Franzen, Elizabeth M. Waldram, Keith J. B. Grainge, Michael P. Hobson, Natasha Hurley-Walker, Anthony Lasenby, Malak Olamaie, Guy G. Pooley, Julia M. Riley, Carmen Rodriguez-Gonzalvez, Richard D. E. Saunders, Anna M. M. Scaife, Michel P. Schammel, Paul F. Scott, Timothy W. Shimwell, David J. Titterington, Jonathan T. L. Zwart

摘要:

第十届剑桥(10 C)调查的射电源,进行了使用AMI大阵列(LA)在15.7 GHz的观测频率的第一批结果,介绍。调查区域面积约为27平方米。度到1 mJy的通量密度完整性。一些较深区域的结果,覆盖约12平方米。度,完全包含在总面积和完成0.5兆焦耳,也提出了。这两个领域的完整性估计至少为93%,源目录载有1 897个条目,可在www.mrao.cam.ac.uk/surveys/10C上查阅。它与9 C调查的结果相结合,计算了15.7 GHz源计数。一个破碎的幂律被发现提供了一个很好的参数化之间的微分计数0.5毫焦耳和1焦耳。将测量的计数与de Zotti等人(2005年)预测的计数进行了比较。该模型在最高通量密度下显示出与数据的良好一致性,但对0.5 mJy和1 Jy之间的综合计数的预测不足约30%。这种匹配提供的证据表明,在典型的1.4- 15.7-GHz的频谱指数的15.7-GHz的选定源人口与减少通量密度对sub-mJy水平的变化-频谱往往变得不那么陡峭。用于检测扩展源的自动化方法已被应用于数据;发现大约5%的源相对于约30弧秒的LA合成束被扩展。使用更高分辨率的数据进行的研究表明,大多数16 GHz的真正扩展源都是经典的双星,尽管也发现了一些附近的星系和双喷流源。

英文摘要:

The first results from the Tenth Cambridge (10C) Survey of Radio Sources, carried out using the AMI Large Array (LA) at an observing frequency of 15.7 GHz, are presented. The survey fields cover an area of approximately 27 sq. degrees to a flux-density completeness of 1 mJy. Results for some deeper areas, covering approximately 12 sq. degrees, wholly contained within the total areas and complete to 0.5 mJy, are also presented. The completeness for both areas is estimated to be at least 93 per cent. The source catalogue contains 1897 entries and is available at www.mrao.cam.ac.uk/surveys/10C. It has been combined with that of the 9C Survey to calculate the 15.7-GHz source counts. A broken power law is found to provide a good parameterisation of the differential count between 0.5 mJy and 1 Jy. The measured count has been compared to that predicted by de Zotti et al. (2005). The model displays good agreement with the data at the highest flux densities but under-predicts the integrated count between 0.5 mJy and 1 Jy by about 30 per cent. Entries from the source catalogue have been matched to those contained in the catalogues of NVSS and FIRST (both of which have observing frequencies of 1.4 GHz). This matching provides evidence for a shift in the typical 1.4-to-15.7-GHz spectral index of the 15.7-GHz-selected source population with decreasing flux density towards sub-mJy levels - the spectra tend to become less steep. Automated methods for detecting extended sources have been applied to the data; approximately 5 per cent of the sources are found to be extended relative to the LA synthesised beam of approximately 30 arcsec. Investigations using higher-resolution data showed that most of the genuinely extended sources at 16 GHz are classical doubles, although some nearby galaxies and twin-jet sources were also identified.

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