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arXiv 0901.4330astro-ph.CO
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31 GHz低频选射电源的测量

A 31 GHz Survey of Low-Frequency Selected Radio Sources

B. S. Mason, L. C. Weintraub, J. L. Sievers, J. R. Bond, S. T. Myers, T. J. Pearson, A. C. S. Readhead, M. C. Shepherd

摘要:

100米罗伯特·C。伯德绿岸望远镜(GBT)和欧文斯谷射电天文台(OVRO)40米射电望远镜已被用于对143平方度天空中的3165个已知河外射电源进行调查。目标源是从宇宙背景成像仪(CBI)观测的NRAO VLA巡天中选择的;大多数是河外活动星系核(AGN),1.4 GHz通量密度为3至10 mJy。由此产生的31 GHz目录完整在线呈现。使用极大似然分析来获得这些源的1.4至31 GHz频谱指数的分布的无偏估计,我们发现平均31至1.4 GHz通量比为0.110 +/- 0.003,对应于α =-0.71 +/- 0.01的频谱指数(S ~ nu^alpha); 9.0 +/-0.8%的源具有alpha > -0.5,1.2 +/-0.2%具有alpha > 0。通过将该谱指数分布与1.4 GHz源计数相结合,我们预测31 GHz源计数在1 mJy < S_31 < 4 mJy范围内,N(>S_31)=(16.7 +/- 1.7)deg^2(S_31/1 mJy)^(-0.80 +/- 0.07)。我们还评估了mJy级(S_1.4 < 3.4 mJy)射电源对31 GHz CMB功率谱的贡献,发现平均功率为ell(ell+1)C^src_ell/(2 pi)= 44 +/- 14微开尔文^2,在ell = 2500时,95%的上限为80微开尔文^2。包括导致S_1.4 = 1 mJy以下的计数升高的源群的12微开尔文^[2]的估计贡献,这相当于解释CBI高电子过剩信号所需的275 +/- 63微开尔文^[2]的21 +/-7%。这些结果与31 GHz点源前景的其他测量结果一致。

英文摘要:

The 100-m Robert C. Byrd Green Bank Telescope (GBT) and the Owens Valley Radio Observatory (OVRO) 40-m radio telescope have been used to conduct a survey of 3165 known extragalactic radio sources over 143 square degrees 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 (AGN) with 1.4 GHz flux densities of 3 to 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 to 31 GHz spectral indices of these sources, we find a mean 31 to 1.4 GHz flux ratio of 0.110 +/- 0.003 corresponding to a spectral index of alpha=-0.71 +/- 0.01 (S ~ nu^alpha); 9.0 +/- 0.8 % of sources have alpha > -0.5 and 1.2 +/- 0.2 % have alpha > 0. By combining this spectral index distribution with 1.4 GHz source counts we predict 31 GHz source counts in the range 1 mJy < S_31 < 4 mJy, N(>S_31) = (16.7 +/- 1.7) deg^2 (S_31/1 mJy)^(-0.80 +/- 0.07). We also assess the contribution of mJy-level (S_1.4 < 3.4 mJy) radio sources to the 31 GHz CMB power spectrum, finding a mean power of ell (ell+1) C^src_ell/(2 pi) = 44 +/- 14 micro-Kelvin^2 and a 95% upper limit of 80 micro-Kelvin^2 at ell = 2500. Including an estimated contribution of 12 micro-Kelvin^2 from the population of sources responsible for the turn-up in counts below S_1.4 = 1 mJy this amounts to 21 +/- 7 % of what is needed to explain the CBI high-ell excess signal, 275 +/- 63 micro-Kelvin^2. These results are consistent with other measurements of the 31 GHz point source foreground.

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