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arXiv 1104.2520astro-ph.CO
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被星系团A2667透镜化的光学脱落星系

Optical dropout galaxies lensed by the cluster A2667

Nicolas Laporte, Roser Pelló, Daniel Schaerer, Johan Richard, Eiichi Egami, Jean-Paul Kneib, Jean-François Le Borgne, Alexandre Maizy, Frederic Boone, Patrick H… 展开作者

Nicolas Laporte, Roser Pelló, Daniel Schaerer, Johan Richard, Eiichi Egami, Jean-Paul Kneib, Jean-François Le Borgne, Alexandre Maizy, Frederic Boone, Patrick Hudelot, Yannick Mellier

摘要:

我们研究了透镜星系团A2667背后的z,Y和J-脱落星系的性质和物理性质。这个领域是我们的项目的一部分,旨在确定z~7-10的候选人可访问的光谱研究,基于深测光与ESO/VLT HAWK-I和FORS 2(zYJH和KS波段图像,AB(3西格玛)~26-27)的透镜集群的样本提取从我们的多波长组合调查与SPITZER,HST,和Herschel。在本文中,我们专注于完整的Y和J-脱落样本,以及满足Capak等人(2011)选择标准的明亮z-脱落样本。在~33 arcmin 2的公共视野内选择10个候选物(一旦针对污染和透镜稀释校正有效面积)。除J和/或IRAC 3.6/4.5外,所有这些都在H和Ks带中检测到,H(AB)约为23.4至25.2,并且具有适度的放大因子。虽然最佳拟合测光红移将所有这些候选者都放在高z,但根据以前的研究,以及与空白场WIRCAM超深巡天(WUDS)的比较,低z闯入者的污染估计为50-75%。当光度红移包括光度先验时,也得到了同样的结果,这使得我们可以去除一半的原始样本,因为它们可能是z~1.7-3的具有年轻恒星脉动和强烈消光的闯入者。剩余样品中的另外两个来源可以基于24微米处的检测和HST z_850带在低z处识别。这些低z闯入者不能很好地描述当前的模板,给出了大的突破,不能很容易地识别,仅基于光学和近红外测光。考虑到估计的尘埃消光和高SFR,其中一些也可以在IR或亚毫米波段检测到。在对可能的污染物进行校正后,在z>7.5处观察到的计数似乎与演变的LF一致。(节略)

英文摘要:

We investigate the nature and the physical properties of z, Y and J-dropout galaxies selected behind the lensing cluster A2667. This field is part of our project aimed at identifying z~7-10 candidates accessible to spectroscopic studies, based on deep photometry with ESO/VLT HAWK-I and FORS2 (zYJH and Ks-band images, AB(3 sigma)~26-27) on a sample of lensing clusters extracted from our multi-wavelength combined surveys with SPITZER, HST, and Herschel. In this paper we focus on the complete Y and J-dropout sample, as well as the bright z-dropouts fulfilling the selection criteria by Capak et al. (2011). 10 candidates are selected within the common field of ~33 arcmin2 (effective area once corrected for contamination and lensing dilution). All of them are detected in H and Ks bands in addition to J and/or IRAC 3.6/4.5, with H(AB)~23.4 to 25.2, and have modest magnification factors. Although best-fit photometric redshifts place all these candidates at high-z, the contamination by low-z interlopers is estimated at 50-75% level based on previous studies, and the comparison with the blank-field WIRCAM Ultra-Deep Survey (WUDS). The same result is obtained when photometric redshifts include a luminosity prior, allowing us to remove half of the original sample as likely z~1.7-3 interlopers with young stellar pulations and strong extinction. Two additional sources among the remaining sample could be identified at low-z based on a detection at 24 microns and on the HST z_850 band. These low-z interlopers are not well described by current templates given the large break, and cannot be easily identified based solely on optical and near-IR photometry. Given the estimated dust extinction and high SFRs, some of them could be also detected in the IR or sub-mm bands. After correction for likely contaminants, the observed counts at z>7.5 seem to be in agreement with an evolving LF. (abridged)

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