J- and Ks-Band Galaxy Counts and Color Distributions in the AKARI North Ecliptic Pole Field
J- and Ks-Band Galaxy Counts and Color Distributions in the AKARI North Ecliptic Pole Field
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DOI：
10.1086/513513
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发表时间：
2007-02
期刊：
影响因子：
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通讯作者：
K. Imai;H. Matsuhara;S. Oyabu;T. Wada;T. Takagi;N. Fujishiro;H. Hanami;C. Pearson
中科院分区：
文献类型：
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作者：
K. Imai;H. Matsuhara;S. Oyabu;T. Wada;T. Takagi;N. Fujishiro;H. Hanami;C. Pearson
我们利用基特峰国家天文台2.1m望远镜上的佛罗里达多目标成像近红外Grism观测光谱仪，给出了在Akari北黄道极(NEP)深部场中覆盖750 arcmin 2的J和Ks波段星系的计数和星系颜色。在织女星震级系统中，最深处信噪比为3的极限震级在J和Ks波段分别为21.85和20.15。Akari NEP场中的J和Ks波段星系计数与文献中的其他结果基本一致；然而，我们发现一些迹象表明，星系计数斜率在J∼19.5时和在18.0<；Ks<；19.5星等范围内发生了变化。我们将这一特征解释为在这些震级处优势种群的变化，因为我们还发现在这些震级处B-Ks颜色分布的相关变化，其中在震级范围18.5<；Ks<；19.5中的蓝色样本的数量明显大于Ks<；17.5。
We present the J- and Ks-band galaxy counts and galaxy colors covering 750 arcmin2 in the deep AKARI north ecliptic pole (NEP) field, using the Florida Multi-object Imaging Near-IR Grism Observational Spectrometer on the Kitt Peak National Observatory 2.1 m telescope. The limiting magnitudes with a signal-to-noise ratio of 3 in the deepest regions are 21.85 and 20.15 in the J and Ks bands, respectively, in the Vega magnitude system. The J- and Ks-band galaxy counts in the AKARI NEP field are broadly in good agreement with those of other results in the literature; however, we find some indication of a change in the galaxy number count slope at J ∼ 19.5 and over the magnitude range 18.0 < Ks < 19.5. We interpret this feature as a change in the dominant population at these magnitudes because we also find an associated change in the B - Ks color distribution at these magnitudes, where the number of blue samples in the magnitude range 18.5 < Ks < 19.5 is significantly larger than that of Ks < 17.5.