Properties of discrete X-ray sources in the starburst spiral galaxy M 83
Properties of discrete X-ray sources in the starburst spiral galaxy M 83
复制标题
星爆螺旋星系 M 83 中离散 X 射线源的特性
DOI：
10.1051/0004-6361:20031074
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发表时间：
2003
影响因子：
6.5
通讯作者：
Roberto Soria Kinwah Wu
中科院分区：
文献类型：
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作者：
Roberto Soria Kinwah Wu
我们在ChandraACIS对M83的观测中识别了127个离散源，在0.3- 8.0keV波段的探测极限约为3 × 10（36）erg·s（-1）。我们讨论了大约20个亮度大于或接近10（38）erg s（-1）的明亮光源的单个X射线光谱和时变特性，以及整个样本的统计特性。大约三分之一的亮源显示的X射线光谱在温度低于或接近1 keV时具有黑体成分，加上伽马近似为2.5的幂律成分，这是典型的软态X射线双星;另外三分之一的幂律光谱伽马近似为1.5，与硬态X射线双星一致。两个明亮的源显示出在硬幂律连续体上的发射线，可能是被光电离星云或恒星风包围的X射线双星。在其他明亮的来源中，我们也发现了两个超新星遗迹候选者，在0.5千电子伏的温度下具有光学薄的热等离子体光谱。最亮的两个超软源的黑体温度kT约为70 eV，亮度约为10（38）erg s（-1）。探测到两个周期约为200 s的候选X射线源。一个X射线源对应于背景FRII射电星系的核心。离散源可以根据其空间、颜色和亮度分布分为三组。第一组包括超软源，在1 keV以上没有检测到发射，在<100 eV的温度下有黑体光谱。第二组包括软源，几乎没有或没有检测到超过2千电子伏的发射。它们与螺旋臂和星暴核中的H α发射密切相关，追踪年轻的人口。它们的相对丰度取决于星系中恒星形成活动的当前水平。它们中的大多数可能是超新星遗迹。第三组中的源大多是X射线双星，比其他两组中的源达到更高的X射线光度。作为旧的低质量和年轻的高质量系统的混合物，当与H α发射相关时，整个集团似乎处于中间年龄。颜色-颜色图使我们能够区分软态和硬态的源。
We have identified 127 discrete sources in a Chandra ACIS observation of M83, with a detection limit of approximate to3 x 10(36) erg s(-1) in the 0.3-8.0 keV band. We discuss the individual X-ray spectral and time-variability properties of approximate to20 bright sources with luminosities greater than or similar to10(38) erg s(-1), and the statistical properties of the whole sample. About one third of the bright sources show X-ray spectra with a blackbody component at temperatures less than or similar to1 keV, plus a powerlaw component with Gamma approximate to 2.5, typical of X-ray binaries in a soft state; another third have powerlaw spectra with Gamma approximate to 1.5, consistent with X-ray binaries in a hard state. Two bright sources show emission lines on a hard powerlaw continuum, and are probably X-ray binaries surrounded by a photo-ionized nebula or stellar wind. Among the other bright sources, we also identified two supernova remnant candidates, with optically-thin thermal plasma spectra at temperatures similar to0.5 keV. The two brightest supersoft sources have blackbody temperatures kT approximate to 70 eV and luminosities similar to10(38) erg s(-1). Two candidate X-ray pulsars are detected with periods approximate to200 s. One X-ray source corresponds to the core of a background FRII radio galaxy. The discrete sources can be divided into three groups, based on their spatial, color and luminosity distributions. The first group comprises supersoft sources with no detected emission above 1 keV and blackbody spectra at temperatures <100 eV. The second group consists of soft sources with little or no detected emission above 2 keV. They are strongly correlated with H alpha emission in the spiral arms and starburst nucleus, tracing a young population. Their relative abundance depends on the current level of star-forming activity in the galaxy. Most of them are likely to be supernova remnants. The sources in the third group are mostly X-ray binaries, reaching higher X-ray luminosities than sources in the other two groups. Being a mixture of old low-mass and young high-mass systems, the whole group appears to be of intermediate age when correlated with the H alpha emission. The color-color diagrams allow us to distinguish between sources in a soft and hard state.