A 31 GHz SURVEY OF LOW-FREQUENCY SELECTED RADIO SOURCES
A 31 GHz SURVEY OF LOW-FREQUENCY SELECTED RADIO SOURCES
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对所选低频无线电源的 31 GHz 调查
DOI：
10.1088/0004-637x/704/2/1433
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
M. Shepherd
中科院分区：
文献类型：
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作者：
B. Mason;L. Weintraub;J. Sievers;J. Bond;S. Myers;T. Pearson;A. Readhead;M. Shepherd
100 m 的 Robert C. Byrd Green Bank 望远镜和 40 m 的 Owens Valley 射电天文台望远镜已被用来对 143°deg2 天空中的 3165 个已知的河外射电源进行 31 GHz 勘测。目标源是从 NRAO VLA 巡天系统中由宇宙背景成像仪 (CBI) 观测到的区域中选择的；大多数是河外活动星系核 (AGN)，1.4 GHz 通量密度为 3-10 mJy。由此产生的 31 GHz 目录完整在线呈现。使用最大似然分析来获得这些源的 1.4-31 GHz 频谱指数分布的无偏估计，我们发现平均 31-1.4 GHz 通量比为 0.110 ± 0.003，对应于频谱指数 α = -0.71 ± 0.01 (Sν ∝ να)； 9.0% ± 0.8% 的源具有 α > − 0.5 和 1.2% ± 0.2% 具有 α > 0。通过将此光谱指数分布与 1.4 GHz 源计数相结合，我们预测 31 GHz 源计数范围为 1 mJy < S31 < 4 mJy，N(>S31) = (16.7 ± 1.7) deg-2(S31/1 mJy)−0.80±0.07。我们还评估了 mJy 级 (S1.4 GHz < 3.4 mJy) 无线电源对 31 GHz 宇宙微波背景功率谱的贡献，发现平均功率为 ℓ(ℓ + 1)Csrcℓ/(2π) = 44 ± 14 μK2，在 ℓ = 时 95% 上限为 80 μK2 2500。包括来自负责 S1.4GHz = 1mJy 以下计数出现的源总体的 12μK2 估计贡献，这相当于解释 CBI 高 ℓ 过量信号 275 ± 63μK2 所需的 21% ± 7%。这些结果与 31 GHz 点源前景的其他测量结果一致。
The 100 m Robert C. Byrd Green Bank Telescope and the 40 m Owens Valley Radio Observatory telescope have been used to conduct a 31 GHz survey of 3165 known extragalactic radio sources over 143 deg2 of the sky. Target sources were selected from the NRAO VLA Sky Survey in fields observed by the Cosmic Background Imager (CBI); most are extragalactic active galactic nuclei (AGNs) with 1.4 GHz flux densities of 3–10 mJy. The resulting 31 GHz catalogs are presented in full online. Using a maximum-likelihood analysis to obtain an unbiased estimate of the distribution of the 1.4–31 GHz spectral indices of these sources, we find a mean 31–1.4 GHz flux ratio of 0.110 ± 0.003 corresponding to a spectral index of α = −0.71 ± 0.01 (Sν ∝ να); 9.0% ± 0.8% of sources have α > − 0.5 and 1.2% ± 0.2% have α > 0. By combining this spectral-index distribution with 1.4 GHz source counts, we predict 31 GHz source counts in the range 1 mJy < S31 < 4 mJy, N(>S31) = (16.7 ± 1.7) deg-2(S31/1 mJy)−0.80±0.07. We also assess the contribution of mJy-level (S1.4 GHz < 3.4 mJy) radio sources to the 31 GHz cosmic microwave background power spectrum, finding a mean power of ℓ(ℓ + 1)Csrcℓ/(2π) = 44 ± 14 μK2 and a 95% upper limit of 80 μK2 at ℓ = 2500. Including an estimated contribution of 12 μK2 from the population of sources responsible for the turn-up in counts below S1.4 GHz = 1 mJy, this amounts to 21% ± 7% of what is needed to explain the CBI high-ℓ excess signal, 275 ± 63 μK2. These results are consistent with other measurements of the 31 GHz point-source foreground.