Multicolor Photometric Observations of Candidate Optical Counterparts to ROSAT Faint X-Ray Sources in a 1 Square Degree Field of the BATC Survey
Multicolor Photometric Observations of Candidate Optical Counterparts to ROSAT Faint X-Ray Sources in a 1 Square Degree Field of the BATC Survey
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DOI：
10.1086/383206
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
Haotong Zhang;S. Xue;D. Burstein;Xu Zhou;Zhao-ji Jiang;Hong Wu;Jun Ma;Jian-sheng Chen;Z. Zou
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文献类型：
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作者：
Haotong Zhang;S. Xue;D. Burstein;Xu Zhou;Zhao-ji Jiang;Hong Wu;Jun Ma;Jian-sheng Chen;Z. Zou
我们提出了75个X射线源的光学候选者，它们位于与Molthagen等人1997年中深ROSAT巡天重叠的101 deg 2区域。这些候选者是使用北京-亚利桑那州-台湾-康涅狄格州（BATC）巡天T329场的CCD成像观测选择的，该望远镜使用NAOC 0.6/0.9 m施密特望远镜，带有15个覆盖3360-9745 nm波长范围的中频带滤光片。这些X射线源相对较暗（CR <0.2 s-1），因此大多数不包括在ROSAT亮源目录中;在汉堡类星体巡天进行的先前识别计划中，它们仍然是没有光学候选物的X射线源。在它们的位置误差圆内，几乎所有的X射线源都被观察到包含一个或多个空间相关的光学候选物，其幅度低至mV <$23.1。我们已经分类149 156检测到的光学候选人与73的75个X射线源与一种新的方法，预测非恒星物体的红移，我们称之为基于SED的对象分类方法。这些光学候选者包括31个类星体，39颗恒星，37个星暴星系，42个星系和7个“刚刚”可见的物体。28个X射线误差圆中只有一个可见物体：9个类星体，3个正常星系，8个星暴星系，6颗恒星和2个刚刚可见的物体。我们还将这些光学物体的位置与NASA河外数据库，FIRST射电源目录和2微米全天巡天进行了交叉相关。另外，我们还对视野中剩余的6011个物体进行了SED分类。光学天体的出现频率高于随机分布的6.5 σ;只有类星体的出现频率高于4 σ。我们估计了所有河外天体的红移，发现我们预测的红移和测量的红移之间有很好的对应关系（Δz的平均误差为0.04）。在这个方向上似乎有一个z = 0.3-0.35的超星系团，包括许多在这个红移范围内发现的X射线误差圆中的星系。
We present optical candidates for 75 X-ray sources in a ∼1 deg2 overlapping region with the 1997 medium-deep ROSAT survey by Molthagen et al. These candidates are selected using the multicolor CCD imaging observations made for the T329 field of the Beijing-Arizona-Taiwan-Connecticut (BATC) Sky Survey, which uses the NAOC 0.6/0.9 m Schmidt telescope with 15 intermediate-band filters covering the wavelength range 3360–9745 Å. These X-ray sources are relatively faint (CR ≪ 0.2 s-1) and thus are mostly not included in the ROSAT Bright Source Catalogue; they also remain as X-ray sources without optical candidates in a previous identification program carried out by the Hamburg Quasar Survey. Within their position error circles, almost all of the X-ray sources are observed to contain one or more spatially associated optical candidates down to the magnitude mV ∼ 23.1. We have classified 149 of 156 detected optical candidates with 73 of the 75 X-ray sources with a new method that predicts a redshift for nonstellar objects, which we have termed the SED-based Object Classification Approach. These optical candidates include 31 QSOs, 39 stars, 37 starburst galaxies, 42 galaxies, and seven "just"-visible objects. Twenty-eight X-ray error circles have only one visible object in them: nine QSOs, three normal galaxies, eight starburst galaxies, six stars, and two of the just-visible objects. We have also cross-correlated the positions of these optical objects with NASA Extragalactic Database, the FIRST radio source catalog, and the Two Micron All Sky Survey. Separately, we have also SED-classified the remaining 6011 objects in our field of view. Optical objects are found at the 6.5 σ level above what one would expect from a random distribution; only QSOs are overrepresented in these error circles at greater than 4 σ frequency. We estimate redshifts for all extragalactic objects and find a good correspondence between our predicted redshift and the measured redshift (a mean error of 0.04 in Δz). There appears to be a supercluster at z ∼ 0.3–0.35 in this direction, including many of the galaxies in the X-ray error circles that are found in this redshift range.