An Australia Telescope survey for CMB anisotropies
An Australia Telescope survey for CMB anisotropies
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澳大利亚望远镜对宇宙微波背景各向异性的调查
DOI：
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发表时间：
2000
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通讯作者：
Ucb
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作者：
R. Subrahmanyan;M. Kesteven;R. Ekers;M. Sinclair;J. S. Atnf;Australia.;Rri;India.;Ucb
我们已经调查了六个不同的“空场”使用澳大利亚望远镜紧凑阵列（ATCA）在一个超紧凑的配置与成像的目的，具有高亮度灵敏度，任何弧分尺度的亮度-温度各向异性的背景无线电天空。在8.7 GHz的频率下观察到六个分离良好的区域，并且测量区域受到ATCA初级束的限制，该初级束在该频率下的半高全宽为6弧分;所有场的分辨率为2弧分，均方根热噪声为24 μJy束-1。在减去在更高分辨率的图像中检测到的前景混淆后，斯托克斯I图像中的残留波动与来自热噪声和较弱（未识别）的前景源的预期一致;斯托克斯Q和U图像与来自热噪声的预期一致。
在我们观测的灵敏度范围内，我们没有理由相信在所观测的微波天空中有任何Sunyaev-Zeldovich洞。假设高斯型CMB各向异性具有“平坦”光谱，我们推导出偏振强度Qflat<10-11 μK和总强度Qflat<25 μK的95%置信上限。ATCA滤波器函数在l=4700处达到峰值，并且在l=3350和6050处具有半最大值。
We have surveyed six distinct ‘empty fields’ using the Australia Telescope Compact Array (ATCA) in an ultracompact configuration with the aim of imaging, with a high brightness sensitivity, any arcminute-scale brightness-temperature anisotropies in the background radio sky. The six well-separated regions were observed at a frequency of 8.7 GHz, and the survey regions were limited by the ATCA primary beams which have a full width at half-maximum of 6 arcmin at this frequency; all fields were observed with a resolution of 2 arcmin and an rms thermal noise of 24 μJy beam−1. After subtracting foreground confusion detected in higher resolution images of the fields, residual fluctuations in Stokes I images are consistent with the expectations from thermal noise and weaker (unidentified) foreground sources; the Stokes Q and U images are consistent with expectations from thermal noise.
Within the sensitivity of our observations, we have no reason to believe that there are any Sunyaev–Zeldovich holes in the microwave sky surveyed. Assuming Gaussian-form CMB anisotropy with a ‘flat’ spectrum, we derive 95 per cent confidence upper limits of Qflat<10–11 μK in polarized intensity and Qflat<25 μK in total intensity. The ATCA filter function peaks at l=4700 and has half-maximum values at l=3350 and 6050.