论文标题
超X射线源的同步加速器截止
Synchrotron cutoff in Ultraluminous X-ray sources
论文作者
论文摘要
在超X射线源中，能量$ e \ simeq 10 $ keV的光谱曲率的起源尚不清楚。在本文中，我们提出了一种基于同步加速器辐射的新型机制来解释此临界值。我们表明，由于同步加速器辐射的纬度变化，相对论血浆可以引起中子星磁场的观察到的光谱曲率。我们分析了两个明亮的脉冲星ULX的Nustar数据，NGC 5907 ULX1和NGC 7793 P13，并提供了这些来源物理参数的估计。我们在各种纬度上符合同步发射的数据，并表明可以在这些情况下为大量可接受的物理参数（例如，具有$γ\ simeq 20 $的半偏等等离子体的高纬度或高度相关等方面的umpativicativical trabilitial for Emporiation for Emportial for Empimation a Empimation of Empimation for Empimative of Empimative flanitive of Empime flabore的频谱截止$ b \ simeq 10^{12} \，\ rm g $的磁场。我们还讨论了如何将这种排放机制与其他提出的模型区分开。我们研究的推论是，大多数ULX可能是中子星，因为它们显示出如此光谱的截止。
The origin of spectral curvature at energies $E\simeq 10$ keV in ultraluminous X-ray sources is not well understood. In this paper, we propose a novel mechanism based on synchrotron radiation to explain this cutoff. We show that relativistic plasma can give rise to observed spectral curvature for neutron star magnetic fields due to the variation in the latitude of synchrotron radiation. We analyze the NuSTAR data of two bright pulsar ULXs, NGC 5907 ULX1 and NGC 7793 P13, and provide estimates of the physical parameters of these sources. We fit the data for synchrotron emission at various latitudes and show that the spectral cutoff in these cases can be explained for a large range of acceptable physical parameters, e.g., a semi-relativistic plasma with $γ\simeq 20$ for high latitudes or a highly relativistic plasma ($γ\simeq 10^5$) for emission close to the electron's orbital plane in a typical magnetic field of $B\simeq 10^{12} \, \rm G$. We also discuss how such an emission mechanism can be distinguished from other proposed models. A corollary to our study is that most ULXs might be neutron stars as they display such a spectral cutoff.
