Chandra Multiwavelength Project. II. First Results of X-Ray Source Properties
Chandra Multiwavelength Project. II. First Results of X-Ray Source Properties
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钱德拉多波长项目。
DOI：
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发表时间：
2003
期刊：
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通讯作者：
A. Vikhlinin
中科院分区：
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作者：
D. Kim;B. Wilkes;P. Green;R. Cameron;J. Drake;N. Evans;P. Freeman;T. Gaetz;H. Ghosh;F. R. Harnden, Jr.;M. Karovska;V. Kashyap;P. Maksym;P. Ratzlaff;E. Schlegel;J. Silverman;H. Tananbaum;A. Vikhlinin
钱德拉多波长项目 (ChaMP) 是对偶然发现的钱德拉 X 射线源进行的广域 (~14 deg2) 调查，旨在建立公平的统计样本，涵盖钱德拉深场之间通量水平 (fX ~ 10-15 至 10-14 ergs s-1 cm-2) 的广泛特征（例如吸收的活动星系核 [AGN] 和高 z 星系团）调查和之前的任务。我们展示了从 62 个观测的初始样本中获得的 X 射线源特性的第一个结果。使用专门为 ChaMP 开发的技术对数据进行统一缩减和分析，然后通过目视检查进行验证。仅利用近轴 X 射线亮源（以避免由不完整性和爱丁顿偏差引起的问题），我们推导了软（0.5-2 keV）和硬（2-8 keV）能带中的 log N-log S 关系。 ChaMP 数据与 ROSAT、ASCA 和 Chandra 深场调查之前的结果一致。特别是，我们的数据很好地填补了钱德拉深场数据和之前的 ASCA 数据之间的硬带通量差距。我们检查簇和非簇场之间的源密度是否存在任何系统差异，并寻找场与场之间的变化，这两者都已在之前报道过。我们发现，在样本中包含的通量水平的统计数据 (~1 σ) 中，任何一个测试都没有发现显着的场与场之间的宇宙变化。在X射线颜色-颜色图中，大多数源落在光子指数= 1.5-2和NH=几×1020 cm2的位置，表明它们是典型的宽线活动星系核。还存在相当多的具有特殊 X 射线颜色的源（例如，高度吸收、非常硬、非常软）。我们证实了这样一个趋势：平均而言，X 射线颜色随着计数率的降低而变硬。由于硬化仅限于最软的能带（0.3-0.9 keV），因此我们得出结论，这很可能是由于吸收造成的。我们将 X 射线源与其他目录进行交叉关联，并根据光学颜色、X 射线与光学光度比和 X 射线颜色来描述它们的属性。
The Chandra Multiwavelength Project (ChaMP) is a wide-area (~14 deg2) survey of serendipitous Chandra X-ray sources, aiming to establish fair statistical samples covering a wide range of characteristics (such as absorbed active galactic nuclei [AGNs] and high-z clusters of galaxies) at flux levels (fX ~ 10-15 to 10-14 ergs s-1 cm-2) intermediate between the Chandra Deep Field surveys and previous missions. We present the first results of X-ray source properties obtained from the initial sample of 62 observations. The data have been uniformly reduced and analyzed with techniques specifically developed for the ChaMP and then validated by visual examination. Utilizing only near-on-axis X-ray-bright sources (to avoid problems caused by incompleteness and the Eddington bias), we derive the log N- log S relation in soft (0.5-2 keV) and hard (2-8 keV) energy bands. The ChaMP data are consistent with previous results of ROSAT, ASCA, and Chandra Deep Field surveys. In particular, our data nicely fill in the flux gap in the hard band between the Chandra Deep Field data and the previous ASCA data. We check whether there is any systematic difference in the source density between cluster and noncluster fields and also search for field-to-field variation, both of which have been previously reported. We found no significant field-to-field cosmic variation in either test within the statistics (~1 σ) across the flux levels included in our sample. In the X-ray color-color plot, most sources fall in the location characterized by photon index = 1.5-2 and NH = a few × 1020 cm2, suggesting that they are typical broadline AGNs. There also exist a considerable number of sources with peculiar X-ray colors (e.g., highly absorbed, very hard, very soft). We confirm a trend that on average the X-ray color hardens as the count rate decreases. Since the hardening is confined to the softest energy band (0.3-0.9 keV), we conclude that it is most likely due to absorption. We cross-correlate the X-ray sources with other catalogs and describe their properties in terms of optical color, X-ray-to-optical luminosity ratio, and X-ray colors.