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arXiv 0707.4482astro-ph
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高红移射电星系4C41.17的宽视场中红外和毫米成像

Wide-field mid-infrared and millimetre imaging of the high-redshift radio galaxy, 4C41.17

T. R. Greve, D. Stern, R. J. Ivison, C. De Breuck, A. Kovács, F. Bertoldi

摘要:

我们提出了深350-和1200微米的成像区域周围4C41.17 -最遥远的(z = 3.792)和明亮的已知射电星系之一-获得亚毫米高角分辨率相机(SHARC-II)和马克斯普朗克毫米波测辐射热计阵列(MAMBO)。射电星系在350微米和1200微米处被稳健地探测到,附近的两个850微米选定的星系也是如此;第三个850微米的源在350微米处被探测到,与1200微米地图中的~ 2-sigma特征相吻合。在距离射电星系更远的地方,在1200微米处探测到了另外9个源,使在这个领域探测到的(亚)毫米选择星系(SMG)总数达到14个。使用来自甚大阵列(VLA)和斯皮策中红外(中红外)数据的无线电图像,我们在4C41.17周围的14个SMG中发现了8个统计上稳健的无线电和/或24微米对应物。Keck/LRIS的后续光谱学已经为八个被稳健识别的SMG中的三个产生了红移,将它们置于红移范围0.5 < z < 2.7,即远低于4C41.17。我们利用IRAC波段探测到的1.6微米(静止坐标系)恒星特征推断另外四个源的光度红移;其中只有一个可能与4C41.17的红移相同。因此,4C41.17场中至少有四个,甚至多达七个SMG在物理上与射电星系无关。有了这些红移信息,我们可以将观测到的射电星系半径为R=50和100”(z = 3.8时为~ 0.4和~ 0.8Mpc)的超密度限制在约5倍和~ 2倍的场,在R=150”时下降到背景值。[摘要]

英文摘要:

We present deep 350- and 1200-micron imaging of the region around 4C41.17 -- one of the most distant (z = 3.792) and luminous known radio galaxies -- obtained with the Submillimeter High Angular Resolution Camera (SHARC-II) and the Max Planck Millimeter Bolometer Array (MAMBO). The radio galaxy is robustly detected at 350- and 1200-micron, as are two nearby 850-micron-selected galaxies; a third 850-micron source is detected at 350-micron and coincides with a ~ 2-sigma feature in the 1200-micron map. Further away from the radio galaxy an additional nine sources are detected at 1200-micron, bringing the total number of detected (sub)millimeter selected galaxies (SMGs) in this field to 14. Using radio images from the Very Large Array (VLA) and Spitzer mid-infrared (mid-IR) data, we find statistically robust radio and/or 24-micron counterparts to eight of the 14 SMGs in the field around 4C41.17. Follow-up spectroscopy with Keck/LRIS has yielded redshifts for three of the eight robustly identified SMGs, placing them in the redshift range 0.5 < z < 2.7, i.e. well below that of 4C41.17. We infer photometric redshifts for a further four sources using their 1.6-micron (rest-frame) stellar feature as probed by the IRAC bands; only one of them is likely to be at the same redshift as 4C41.17. Thus at least four, and as many as seven, of the SMGs within the 4C41.17 field are physically unrelated to the radio galaxy. With the redshift information at hand we are able to constrain the observed over-densities of SMGs within radial bins stretching to R=50 and 100" (~ 0.4 and ~ 0.8Mpc at z ~ 3.8) from the radio galaxy to ~ 5x and ~ 2x that of the field, dropping off to the background value at R=150". [Abridged]

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