A Chandra Study of the Circinus Galaxy Point-Source Population
A Chandra Study of the Circinus Galaxy Point-Source Population
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圆规座星系点源群的钱德拉研究
DOI：
10.1086/321123
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
T. University
中科院分区：
文献类型：
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作者：
F. Bauer;W. Brandt;R. Sambruna;G. Chartas;G. Garmire;S. Kaspi;H. University;G. University;T. University
我们使用钱德拉x射线天文台从空间和光谱上解析了circirus星系的x射线发射。我们在此报告了与Circinus盘相关的离核点源的x射线发射性质，它占总发射0.5-10 keV的约34%。我们发现许多偶然的x射线源都集中在星系的光盘上，尽管很少有光学对应的x射线位置在1″以内，直到mV = 23-25的极限星等。在环星座（≈3.8 Mpc）的距离上，它们的固有亮度在0.5-10 keV之间，从≈2 × 1037 ergs -1到≈4 × 1039 ergs -1。在67ks的观测期间，四分之一的源是可变的，对这些非核源的光谱拟合显示出不同范围的光谱特性。点源的总体特征表明，大多数是环座内的x射线双星和/或超亮超新星遗迹。我们能够更详细地分析两种最强的非核源，并发现它们都具有非凡的特性。两个光源的x射线平均光度分别为3.7 × 1039 ergs -1和3.4 × 1039 ergs -1。前者显示出每7.5小时的大周期通量变化，并与Tin = 1.35 keV的多色黑体吸积盘模型很好地拟合，其性质与日食≥50 M⊙黑洞双星相一致。后者似乎是一个年轻的超新星遗迹，因为它与一个非热无线电对应物和一个Hα探测到的H II区相吻合。该源显示出长期（≈4年）的x射线变异性和6.67-6.97 keV的铁发射在线混合，等效宽度为1.6 keV。这两个天体进一步支持了这样一种观点，即附近星系中的超级爱丁顿x射线源可以用x射线双星中的中等质量黑洞和年轻超新星遗迹的混合物来解释。
We have used the Chandra X-Ray Observatory to resolve spatially and spectrally the X-ray emission from the Circinus galaxy. We report here on the nature of the X-ray emission from the off-nuclear point sources associated with the disk of Circinus, which make up ≈34% of the total 0.5–10 keV emission. We find that many of the serendipitous X-ray sources are concentrated along the optical disk of the galaxy, although few have optical counterparts within 1″ of their X-ray positions down to limiting magnitudes of mV = 23–25. At the distance of Circinus (≈3.8 Mpc), their intrinsic 0.5–10 keV luminosities range from ≈2 × 1037 ergs s-1 to ≈4 × 1039 ergs s-1. One-fourth of the sources are variable over the duration of the 67 ks observation, and spectral fitting of these off-nuclear sources shows a diverse range of spectral properties. The overall characteristics of the point sources suggest that most are X-ray binaries and/or ultraluminous supernova remnants within Circinus. We are able to analyze the two strongest off-nuclear sources in greater detail and find both to have remarkable properties. The average X-ray luminosities of the two sources are 3.7 × 1039 ergs s-1 and 3.4 × 1039 ergs s-1. The former displays large and periodic flux variations every 7.5 hr and is well fitted by a multicolor blackbody accretion disk model with Tin = 1.35 keV, properties consistent with an eclipsing ≳50 M⊙ black hole binary. The latter appears to be a young supernova remnant, as it coincides with a nonthermal radio counterpart and an Hα-detected H II region. This source exhibits both long-term (≈4 yr) X-ray variability and a 6.67–6.97 keV iron emission-line blend with a 1.6 keV equivalent width. These two objects further support the notion that super-Eddington X-ray sources in nearby galaxies can be explained by a mixture of intermediate-mass black holes in X-ray binaries and young supernova remnants.