LOFAR 再电离时期窗口的初步深度观测：I. 北天极
天体物理仪器与方法
2013-07-19 v2 宇宙学与河外天体物理
摘要
LOFAR 再电离时期 (EoR) 项目的目标是探测红移 HI 21cm 信号的谱涨落。该信号比天体物理前景信号弱几个数量级，因此为了实现这一目标，必须进行非常长时间的积分、对台站和电离层进行精确校准以及可靠的前景去除。LOFAR EoR 项目的预期观测窗口之一将位于北天极 (NCP) 中心。我们展示了使用 LOFAR 高频天线 (HBA) 阵列在 115 MHz 至 163 MHz 频率范围内对 NCP 窗口的观测结果。数据获取于 2011 年 4 月 LOFAR 的调试阶段。我们使用了长达约 30 km 的基线。通过约 3 个夜晚、每晚 6 小时的有效积分，我们在 NCP 窗口实现了约 100 microJy/PSF 的噪声水平。在靠近 NCP 处，噪声水平增加到约 180 microJy/PSF，这主要是由于未减除的附近源造成的额外污染。我们估计，在我们最好的夜晚，达到的噪声水平仅比由我们银河系和接收机噪声设定的热极限高 1.4 倍。我们的连续谱图像比之前使用 WSRT 和 GMRT 阵列实现的图像深数倍。我们推导了解析解释，认为 excess noise 主要是由于距离 NCP 大角距的源造成的。
引用
@article{arxiv.1301.1630,
title = {Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole},
author = {S. Yatawatta and A. G. de Bruyn and M. A. Brentjens and P. Labropoulos and V. N. Pandey and S. Kazemi and S. Zaroubi and L. V. E. Koopmans and A. R. Offringa and V. Jelic and O. Martinez Rubi and V. Veligatla and S. J. Wijnholds and W. N. Brouw and G. Bernardi and B. Ciardi and S. Daiboo and G. Harker and G. Mellema and J. Schaye and R. Thomas and H. Vedantham and E. Chapman and F. B. Abdalla and A. Alexov and J. Anderson and I. M. Avruch and F. Batejat and M. E. Bell and M. R. Bell and M. Bentum and P. Best and A. Bonafede and J. Bregman and F. Breitling and R. H. van de Brink and J. W. Broderick and M. Bruggen and J. Conway and F. de Gasperin and E. de Geus and S. Duscha and H. Falcke and R. A. Fallows and C. Ferrari and W. Frieswijk and M. A. Garrett and J. M. Griessmeier and A. W. Gunst and T. E. Hassall and J. W. T. Hessels and M. Hoeft and M. Iacobelli and E. Juette and A. Karastergiou and V. I. Kondratiev and M. Kramer and M. Kuniyoshi and G. Kuper and J. van Leeuwen and P. Maat and G. Mann and J. P. McKean and M. Mevius and J. D. Mol and H. Munk and R. Nijboer and J. E. Noordam and M. J. Norden and E. Orru and H. Paas and M. Pandey-Pommier and R. Pizzo and A. G. Polatidis and W. Reich and H. J. A. Rottgering and J. Sluman and O. Smirnov and B. Stappers and M. Steinmetz and M. Tagger and Y. Tang and C. Tasse and S. ter Veen and R. Vermeulen and R. J. van Weeren and M. Wise and O. Wucknitz and P. Zarka},
journal= {arXiv preprint arXiv:1301.1630},
year = {2013}
}
备注
19 pages, 24 figures. Draft version with low resolution images. Accepted on 08/01/2013 Astronomy & Astrophysics. Abstract abridged. Version with high resolution images: http://www.astro.rug.nl/~yatawatta/ncp_eor.pdf