THE SPITZER–WISE SURVEY OF THE ECLIPTIC POLES
THE SPITZER–WISE SURVEY OF THE ECLIPTIC POLES
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DOI：
10.1088/0004-637x/735/2/112
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发表时间：
2011-07
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影响因子：
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通讯作者：
T. Jarrett;M. Cohen;F. Masci;E. L. Wright;D. Stern;D. Benford;A. Blain;S. Carey;R. Cutri
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文献类型：
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作者：
T. Jarrett;M. Cohen;F. Masci;E. L. Wright;D. Stern;D. Benford;A. Blain;S. Carey;R. Cutri
我们利用斯皮策太空望远镜和广域红外巡天探测器（WISE）分别对黄道南北两极EP-N和EP-S进行了观测。主要目标是通过开发一组在这些红外任务中常见的校准恒星，将WISE与斯皮策和中途空间实验（MSX）的光度测量系统进行交叉校准。黄道极点是WISE的连续观测区域，因为它的极交叉轨道，使这些区域成为绝对校准和内部校准的理想区域。斯皮策IRAC和MIPS成像调查覆盖了EP-N的0.40°2和EP-S的1.28°2的完整区域。在为期8个月的低温任务中，WISE在3.4、4.6、12和22 μm四个中红外波段观测了整个天空，包括数百次黄道极通道；在这里，我们报告了WISE实现的最高覆盖深度，两极的面积为1.5°2。位于EP-N中心附近的sy2星系NGC 6552可以作为标准校准器来测量WISE的22 μm通道的红色响应。Spitzer-IRAC/MIPS/IRS-LL和WISE的观测表明，由于恒星形成和活动星系核（AGN）的存在，该星系在中红外波段呈现出强烈的红色，而在基线bb101年的时间里，NGC 6552的中红外光度变化幅度小于2%。将NGC 6552与标准校准星相结合，相对于斯皮策和MSX系统，W1 （3.4 μm）、W2 （4.6 μm）、W3 （12 μm）和W4 （22 μm）的WISE校准精度分别为2.4%、2.8%、4.5%和5.7%。在任务的低温寿命期间，WISE的光度测量内部稳定在0.1%以上。斯皮策- WISE巡天的次要目标是在更大的通量水平深度探索两极，利用更高角度分辨率的斯皮策观测和特别深（总覆盖范围）的WISE观测，这些观测可能达到调查的混淆极限。丰富的斯皮策和WISE数据集被用来通过源计数、彩色星等和彩色图表来研究银河系和星系外的种群。作为数据集促进的一个例子，我们已经从星系中分离了恒星，从幂律主导的agn中描绘了正常星系，并报告了河外种群的不同部分。在EP-N中，我们发现AGN源密度为~ 260°−2，深度为12 μm，深度为115 μJy，占该深度总星系外人口的15%，与在其他领域中观察到的低亮度AGN相似。
We have carried out a survey of the north and south ecliptic poles, EP-N and EP-S, respectively, with the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer (WISE). The primary objective was to cross-calibrate WISE with the Spitzer and Midcourse Space Experiment (MSX) photometric systems by developing a set of calibration stars that are common to these infrared missions. The ecliptic poles were continuous viewing zones for WISE due to its polar-crossing orbit, making these areas ideal for both absolute and internal calibrations. The Spitzer IRAC and MIPS imaging survey covers a complete area of 0.40 deg2 for the EP-N and 1.28 deg2 for the EP-S. WISE observed the whole sky in four mid-infrared bands, 3.4, 4.6, 12, and 22 μm, during its eight-month cryogenic mission, including several hundred ecliptic polar passages; here we report on the highest coverage depths achieved by WISE, an area of ∼1.5 deg2 for both poles. Located close to the center of the EP-N, the Sy-2 galaxy NGC 6552 conveniently functions as a standard calibrator to measure the red response of the 22 μm channel of WISE. Observations from Spitzer-IRAC/MIPS/IRS-LL and WISE show that the galaxy has a strong red color in the mid-infrared due to star-formation and the presence of an active galactic nucleus (AGN), while over a baseline >1 year the mid-IR photometry of NGC 6552 is shown to vary at a level less than 2%. Combining NGC 6552 with the standard calibrator stars, the achieved photometric accuracy of the WISE calibration, relative to the Spitzer and MSX systems, is 2.4%, 2.8%, 4.5%, and 5.7% for W1 (3.4 μm), W2 (4.6 μm), W3 (12 μm), and W4 (22 μm), respectively. The WISE photometry is internally stable to better than 0.1% over the cryogenic lifetime of the mission. The secondary objective of the Spitzer–WISE Survey was to explore the poles at greater flux-level depths, exploiting the higher angular resolution Spitzer observations and the exceptionally deep (in total coverage) WISE observations that potentially reach down to the confusion limit of the survey. The rich Spitzer and WISE data sets were used to study the Galactic and extragalactic populations through source counts, color–magnitude and color–color diagrams. As an example of what the data sets facilitate, we have separated stars from galaxies, delineated normal galaxies from power-law-dominated AGNs, and reported on the different fractions of extragalactic populations. In the EP-N, we find an AGN source density of ∼260 deg−2 to a 12 μm depth of 115 μJy, representing 15% of the total extragalactic population to this depth, similar to what has been observed for low-luminosity AGNs in other fields.