THE NEXT GENERATION VIRGO CLUSTER SURVEY. XV. THE PHOTOMETRIC REDSHIFT ESTIMATION FOR BACKGROUND SOURCES
THE NEXT GENERATION VIRGO CLUSTER SURVEY. XV. THE PHOTOMETRIC REDSHIFT ESTIMATION FOR BACKGROUND SOURCES
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DOI：
10.1088/0004-637x/797/2/102
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发表时间：
2014-10
期刊：
影响因子：
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通讯作者：
A. Raichoor;S. Mei;S. Mei;T. Erben;H. Hildebrandt;M. Huertas-Company;M. Huertas-Company;O. Ilbert
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文献类型：
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作者：
A. Raichoor;S. Mei;S. Mei;T. Erben;H. Hildebrandt;M. Huertas-Company;M. Huertas-Company;O. Ilbert
下一代室女座星系团巡天（NGVS）是以室女座星系团为中心的光学成像巡天，覆盖范围为104 deg2。目前，在u * giz波段观测到了整个勘测区域，在r波段观测到了三分之一的区域。我们提出了NGVS背景源的光度红移估计。经过专门的数据处理后，我们进行精确的测光，特别注意通过点扩散函数均匀化进行精确的颜色测量。然后，我们估计的光度红移的Le Phare和BPZ代码。我们增加了一个新的先验，扩展到iAB = 12.5等。当使用u * griz带时，我们对15.5等的星系的测光红移有偏差。|Δ z| <0.02，小于5%离群值，分散σ outl.rej.，以及Zphot上的个体误差随量值增加（分别从0.02到0.05和从0.03到0.10）。当使用相同星等和红移范围内的u * giz波段时，缺少r波段会增加0.3 μ zphot ≤ 0.8范围内的不确定性（− 0.05 <Δ z <− 0.02，σ outl. rej ≤ 0.06，10%-15%的异常值，以及zphot.err. 0.15）。我们还提出了一个联合分析的光度红移精度作为红移和星等的函数。我们通过与光谱样品的比较，并通过验证整个NGVS光度红移样品在红移仓中的角自相关和互相关函数w（θ）与预期一致，来评估我们的光度红移的质量。
The Next Generation Virgo Cluster Survey (NGVS) is an optical imaging survey covering 104 deg2 centered on the Virgo cluster. Currently, the complete survey area has been observed in the u*giz bands and one third in the r band. We present the photometric redshift estimation for the NGVS background sources. After a dedicated data reduction, we perform accurate photometry, with special attention to precise color measurements through point-spread function homogenization. We then estimate the photometric redshifts with the Le Phare and BPZ codes. We add a new prior that extends to iAB = 12.5 mag. When using the u* griz bands, our photometric redshifts for 15.5 mag ⩽ i ≲ 23 mag or zphot ≲ 1 galaxies have a bias |Δz| < 0.02, less than 5% outliers, a scatter σoutl.rej., and an individual error on zphot that increases with magnitude (from 0.02 to 0.05 and from 0.03 to 0.10, respectively). When using the u*giz bands over the same magnitude and redshift range, the lack of the r band increases the uncertainties in the 0.3 ≲ zphot ≲ 0.8 range (−0.05 < Δz < −0.02, σoutl.rej ∼ 0.06, 10%–15% outliers, and zphot.err. ∼ 0.15). We also present a joint analysis of the photometric redshift accuracy as a function of redshift and magnitude. We assess the quality of our photometric redshifts by comparison to spectroscopic samples and by verifying that the angular auto- and cross-correlation function w(θ) of the entire NGVS photometric redshift sample across redshift bins is in agreement with the expectations.