THE MASSIVE STAR-FORMING REGION CYGNUS OB2. I. CHANDRA CATALOG OF ASSOCIATION MEMBERS
THE MASSIVE STAR-FORMING REGION CYGNUS OB2. I. CHANDRA CATALOG OF ASSOCIATION MEMBERS
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天鹅座 OB2 大型恒星形成区。
DOI：
10.1088/0067-0049/184/1/84
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
J. J. Drake
中科院分区：
文献类型：
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作者：
N. Wright;J. J. Drake
我们展示了在大质量恒星形成区域 (SFR) 天鹅座 OB2 中检测到的 1696 个 X 射线源的目录，这些 X 射线源是从钱德拉对该区域中心的两次档案观测中提取的。利用钱德拉观测的低背景率，采用深源提取例程来最大限度地提高提取源的数量。使用其他波长的观察来识别低计数率源并消除可能的杂散源。蒙特卡罗模拟也用于评估这些来源的真实性。 X 射线光谱与热等离子体模型相匹配来表征物体，并分析 X 射线光曲线以确定其变化性。我们使用贝叶斯技术，利用 INT 光度 Hα 巡天、两微米全天巡天和 UKIRT 红外深空巡天-银河平面巡天的深度观测，识别了 1501 个（89%）源的光学或近红外对应物。这些物体中有 757 个 (45%) 具有六波段 r'、Hα、i'、J、H 和 Ks 光学和近红外光度测量。根据对每个源的泊松假源概率的分析，我们估计我们的 X 射线目录中包含 <1% 的假源，当仅考虑与光学或近红外关联的源时，比例甚至更低。贝叶斯匹配方案的蒙特卡罗模拟允许将该方法与更简化的匹配技术进行比较，并能够量化各种误差源。这里展示的 1696 个物体的目录包括 X 射线宽带通量、模型拟合以及光学和近红外光度测量，这是迄今为止单个恒星形成率最大的 X 射线目录之一。从相对较浅的观测中检测到的大量恒星 X 射线源证实了天鹅座 OB2 作为银河系最大质量恒星形成率之一的地位和重要性。
We present a catalog of 1696 X-ray sources detected in the massive star-forming region (SFR) Cygnus OB2 and extracted from two archival Chandra observations of the center of the region. A deep source extraction routine, exploiting the low background rates of Chandra observations, was employed to maximize the number of sources extracted. Observations at other wavelengths were used to identify low count-rate sources and remove likely spurious sources. Monte Carlo simulations were also used to assess the authenticity of these sources. X-ray spectra were fitted with thermal plasma models to characterize the objects and X-ray light curves were analyzed to determine their variability. We used a Bayesian technique to identify optical or near-IR counterparts for 1501 (89%) of our sources, using deep observations from the INT Photometric Hα survey, the Two Micron All Sky Survey, and the UKIRT Infrared Deep Sky Survey-Galactic Plane Survey. Seven hundred and fifty seven (45%) of these objects have six-band r′, Hα, i′, J, H, and Ks optical and near-IR photometry. From an analysis of the Poisson false-source probabilities for each source we estimate that our X-ray catalog includes <1% of false sources, and an even lower fraction when only sources with optical or near-IR associations are considered. A Monte Carlo simulation of the Bayesian matching scheme allows this method to be compared to more simplified matching techniques and enables the various sources of error to be quantified. The catalog of 1696 objects presented here includes X-ray broadband fluxes, model fits, and optical and near-IR photometry in what is one of the largest X-ray catalog of a single SFR to date. The high number of stellar X-ray sources detected from relatively shallow observations confirms the status and importance of Cygnus OB2 as one of our Galaxy's most massive SFRs.