The recent discoveries of pulsed X-ray emission from three ultraluminous X-ray (ULX) sources have finally enabled us to recognize a subclass within the ULX class: the great pretenders, neutron stars (NSs) that appear to emit X-ray radiation at isotropic luminosities L X = 7 × 1039 erg s-1 - 1 × 1041 erg s-1 only because their emissions are strongly beamed toward our direction and our sight lines are offset by only a few degrees from their magnetic-dipole axes. The three known pretenders appear to be stronger emitters than the presumed black holes of the ULX class, such as Holmberg II & IX X-1, IC10 X-1, and NGC300 X-1. For these three NSs, we have adopted a single reasonable assumption, that their brightest observed outbursts unfold at the Eddington rate, and we have calculated both their propeller states and their surface magnetic-field magnitudes. We find that the results are not at all different from those recently obtained for the Magellanic Be/X-ray pulsars: the three NSs reveal modest magnetic fields of about 0.3-0.4 TG and beamed propeller-line X-ray luminosities of ~ 1036-37 erg s-1, substantially below the Eddington limit.

中文翻译：

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ULX 级中的伟大伪装者

最近发现的来自三个超亮 X 射线 (ULX) 源的脉冲 X 射线发射最终使我们能够识别出 ULX 类中的一个子类：伟大的伪装者，中子星 (NS) 似乎在各向同性光度 LX = 7 × 1039 erg s-1 - 1 × 1041 erg s-1 只是因为它们的发射强烈地射向我们的方向，而我们的视线与它们的磁偶极轴仅偏移几度。三个已知的伪装者似乎是比 ULX 类假定的黑洞更强的发射器，例如 Holmberg II & IX X-1、IC10 X-1 和 NGC300 X-1。对于这三个 NS，我们采用了一个合理的假设，即它们观察到的最亮的爆发以爱丁顿速率展开，我们已经计算了它们的螺旋桨状态和它们的表面磁场大小。我们发现结果与最近获得的麦哲伦 Be/X 射线脉冲星的结果完全不同：三个 NS 显示出大约 0.3-0.4 TG 的适度磁场和约 1036- 37 erg s-1，大大低于爱丁顿极限。