LOFAR 低频天线对 3C295 和 Bootes 天区的观测：源计数与超陡谱源
星系天体物理
2014-09-22 v1 宇宙学与河外天体物理
摘要
我们展示了 LOFAR 低频天线对 Bootes 和 3C295 天区的观测结果。我们在 34、46 和 62 MHz 拍摄的图像噪声水平分别达到 12、8 和 5 mJy beam，使其成为该频段迄今为止最深的图像。总共，我们在每张图像中探测到 300 到 400 个源，覆盖面积为 17 至 52 deg。从观测中我们推导出了欧几里得归一化的微分源计数。62 MHz 的源计数与之前的 GMRT 153 MHz 和 VLA 74 MHz 微分源计数一致，按谱指数 缩放。我们发现需要 的谱指数缩放才能匹配 LOFAR 34 MHz 的源计数。这一结果也与 38 MHz 8C 巡天的源计数一致，表明射电源的平均谱指数在低频端变平。我们还利用 34 至 1400 MHz 之间源的单独流量测量以及计算源群平均谱指数，发现了谱指数变平的证据。为了选择可能与大质量高红移射电星系相关的超陡谱 () 射电源，我们计算了 Bo"otes 天区中源在 62 MHz、153 MHz 和 1.4 GHz 之间的谱指数。我们将这些射电源与光学和红外星表进行交叉关联，并拟合光谱能量分布以获得光度红移。我们发现大多数这些超陡谱源位于 范围内。
引用
@article{arxiv.1409.5437,
title = {LOFAR low-band antenna observations of the 3C295 and Bootes fields: source counts and ultra-steep spectrum sources},
author = {R. J. van Weeren and W. L. Williams and C. Tasse and H. J. A. Rottgering and D. A. Rafferty and S. van der Tol and G. Heald and G. J. White and A. Shulevski and P. Best and H. T. Intema and S. Bhatnagar and W. Reich and M. Steinmetz and S. van Velzen and T. A. Ensslin and I. Prandoni and F. de Gasperin and M. Jamrozy and G. Brunetti and M. J. Jarvis and J. P. McKean and M. W. Wise and C. Ferrari and J. Harwood and J. B. R. Oonk and M. Hoeft and M. Kunert-Bajraszewska and C. Horellou and O. Wucknitz and A. Bonafede and N. R. Mohan and A. M. M. Scaife and H. -R. Klockner and I. M. van Bemmel and A. Merloni and K. T. Chyzy and D. Engels and H. Falcke and M. Pandey-Pommier and A. Alexov and J. Anderson and I. M. Avruch and R. Beck and M. E. Bell and M. J. Bentum and G. Bernardi and F. Breitling and J. Broderick and W. N. Brouw and M. Bruggen and H. R. Butcher and B. Ciardi and E. de Geus and M. de Vos and A. Deller and S. Duscha and J. Eisloffel and R. A. Fallows and W. Frieswijk and M. A. Garrett and J. Griessmeier and A. W. Gunst and J. P. Hamaker and T. E. Hassall and J. Horandel and A. van der Horst and M. Iacobelli and N. J. Jackson and E. Juette and V. I. Kondratiev and M. Kuniyoshi and P. Maat and G. Mann and D. McKay-Bukowski and M. Mevius and R. Morganti and H. Munk and A. R. Offringa and E. Orru and H. Paas and V. N. Pandey and G. Pietka and R. Pizzo and A. G. Polatidis and A. Renting and A. Rowlinson and D. Schwarz and M. Serylak and J. Sluman and O. Smirnov and B. W. Stappers and A. Stewart and J. Swinbank and M. Tagger and Y. Tang and S. Thoudam and C. Toribio and R. Vermeulen and C. Vocks and P. Zarka},
journal= {arXiv preprint arXiv:1409.5437},
year = {2014}
}
备注
26 pages, 20 figures, ApJ in press