We report on the discovery of thermal and nonthermal X-rays from the shells of the superbubble (SB) 30 Dor C in the LMC. The X-ray morphology is a nearly circular shell with a radius of ~40 pc, which is bright on the northern and western sides. The spectra of the shells differ from region to region. The southern shell shows clear emission lines and is well fitted with a model of a thin thermal plasma (kT = 0.21 keV) in nonequilibrium ionization plus a power-law component. This thermal plasma is located inside of the Hα emission, which is the outer edge of the shell of the SB. The northern and western sides of the SB are dim in Hα emission but are bright in nonthermal (power-law) X-rays with a photon index of 2.1-2.9. The nonthermal X-ray shell traces the outer boundary of the radio shell. These features of thin thermal and nonthermal X-rays are similar to those of SN 1006, a prototype of a synchrotron X-ray shell, but the nonthermal component of 30 Dor C is about 10 times brighter than that of SN 1006. 30 Dor C is the first candidate of an extragalactic SB, in which energetic electrons are accelerating in the shell. The age is much older than that of SN 1006, and hence the particle acceleration time in this SB may be longer than those in normal shell-like supernova remnants. We found pointlike sources associated with some of the tight star clusters. The X-ray luminosity and spectrum are consistent with those of young clusters of massive stars. Pointlike sources with nonthermal spectra are also found in the SB. These may be background objects (active galactic nuclei) or stellar remnants (neutron stars or black holes).
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机译：我们报道了从LMC的超级气泡（SB）30 Dor C的壳中发现热和非热X射线的报道。 X射线形态是近乎圆形的壳，半径约为40 pc，在北侧和西侧均较亮。壳的光谱因区域而异。南部的外壳显示出清晰的发射线，并且非常适合非平衡电离中的薄热等离子体（kT = 0.21 keV）模型以及幂律分量。该热等离子体位于Hα发射的内部，该发射是SB外壳的外边缘。 SB的北侧和西侧的Hα发射较暗，但在非热（幂律）X射线中则明亮，光子指数为2.1-2.9。非热X射线外壳跟踪无线电外壳的外边界。薄热X射线和非热X射线的这些特征与同步加速器X射线壳的原型SN 1006相似，但是30 Dor C的非热成分比SN 1006的亮约10倍。30 Dor C是银河系SB的第一个候选者，其中高能电子在壳中加速。该年龄比SN 1006的年龄大得多，因此该SB中的粒子加速时间可能比正常的壳状超新星残骸中的粒子加速时间更长。我们发现了与某些紧密恒星团相关的点状源。 X射线的光度和光谱与年轻的大质量恒星团的光度和光谱一致。在SB中也发现了具有非热光谱的点状光源。这些可能是背景物体（活跃的银河核）或恒星残留物（中子星或黑洞）。
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