LALA鲸鱼座场中的钱德拉X射线源
Chandra X-ray Sources in the LALA Cetus Field
摘要：
大面积莱曼阿尔法巡天（LALA）鲸鱼座领域的174 k钱德拉先进CCD成像光谱仪曝光是LALA领域两个深钱德拉图像中的第二个。在本文中，我们提出的钱德拉X射线源检测到的鲸鱼座领域，随着分析的X射线源计数，叠加X射线光谱，和光学鉴定。共探测到188个X射线源：0.5-7.0 keV波段174个，0.5-2.0 keV波段154个，2.0-7.0 keV波段113个。推导出X射线源计数，并与LALA Bootes场（172 ks曝光）进行比较。有趣的是，我们发现一致的硬带X射线源密度，但在Cetus场中，软带X射线源密度高出36 ± 12%。探测到的X射线源的加权叠加谱可用光子指数γ = 1.55的幂律拟合。在加权叠加谱的基础上，我们发现X射线本底的分辨分数从0.5-1.0 keV的72 ± 1%下降到6.0-8.0 keV的63 ± 4%。在0.5-7 keV的范围内，未分辨的光谱可以通过幂律拟合，光子指数Gamma = 1.22。我们还提出了154个X射线源的光学对应物，下降到r' = 25.9（织女星）的限制幅度，使用深r'带图像获得的MMT。
英文摘要：
The 174 ks Chandra Advanced CCD Imaging Spectrometer exposure of the Large Area Lyman Alpha Survey (LALA) Cetus field is the second of the two deep Chandra images on LALA fields. In this paper we present the Chandra X-ray sources detected in the Cetus field, along with an analysis of X-ray source counts, stacked X-ray spectrum, and optical identifications. A total of 188 X-ray sources were detected: 174 in the 0.5-7.0 keV band, 154 in the 0.5-2.0 keV band, and 113 in the 2.0-7.0 keV band. The X-ray source counts were derived and compared with LALA Bootes field (172 ks exposure). Interestingly, we find consistent hard band X-ray source density, but 36+-12% higher soft band X-ray source density in Cetus field. The weighted stacked spectrum of the detected X-ray sources can be fitted by a powerlaw with photon index Gamma = 1.55. Based on the weighted stacked spectrum, we find that the resolved fraction of the X-ray background drops from 72+-1% at 0.5-1.0 keV to 63+-4% at 6.0-8.0 keV. The unresolved spectrum can be fitted by a powerlaw over the range 0.5-7 keV, with a photon index Gamma = 1.22. We also present optical counterparts for 154 of the X-ray sources, down to a limiting magnitude of r' = 25.9 (Vega), using a deep r' band image obtained with the MMT.
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