EVIDENCE FOR STRONG CYCLOTRON EMISSION IN THE HARD X‐RAY SPECTRUM OF HER X‐1
EVIDENCE FOR STRONG CYCLOTRON EMISSION IN THE HARD X‐RAY SPECTRUM OF HER X‐1
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DOI：
10.1111/j.1749-6632.1977.tb37072.x
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发表时间：
1977-12
影响因子：
5.2
通讯作者：
J. Trümper;W. Pietsch;C. Reppin;B. Sacco;E. Kendziorra;R. Staubert
中科院分区：
文献类型：
--
作者：
J. Trümper;W. Pietsch;C. Reppin;B. Sacco;E. Kendziorra;R. Staubert
从脉冲星物理学中我们知道，中子星的表面磁场必须达到10 ~ 10高斯的量级，甚至可能更高。这些数字是从考虑（1）引力坍缩期间的磁通量守恒，（2）射电双星的磁偶极制动，（3）作用于中子星的吸积力矩得出的。将后一个论点应用于武仙座X-1，Elsner和Lamb 6估计恒星的磁矩为1030 cgs，这导致表面场为10”高斯。Boldt等人曾试图利用光谱数据来估计Her X-1极盖的磁场强度。[3]他们解释了硬X射线光谱在t 25 keV处发生的陡峭截止，该模型假设极冠上方的等离子体在接近电子回旋频率w H的频率处变得光学厚。这些作者发现，t i w H = 100 keV给出了与他们的数据的最佳拟合，其对应于1013高斯的磁场强度。我们注意到，这种估计是模型依赖的，因为它需要假设的空间能量释放分布的吸积质子在极地热点，以及该地区的辐射传热特性。此外，该模型对脉冲轮廓的能量依赖性的预测与我们目前的数据相矛盾。在下文中，我们报告了在53 keV的Her X-1谱中发现的强线特征，我们将其解释为回旋辐射。相应的磁场为4.6 x 10 I2高斯。
It is well known from pulsar physics that neutron stars must possess surface magnetic fields of the order of loio to lo” gauss or possibly even higher. These figures are derived from considerations about ( I ) magnetic flux conservation during the gravitational collapse, (2) magnetic dipole braking of radio pulsars, and (3) accretion torques acting on binary neutron stars. Applying the latter argument to Hercules X-1, Elsner and Lamb6 estimated the stellar magnetic moment to be 1030cgs, which leads to a surface field of 10” gauss. An attempt to use spectral data in order to estimate the magnetic field strength in the polar cap of Her X-l has been made by Boldt et a f . 3 They explain the steep cutoff in the hard x-ray spectrum occurring a t 25 keV by a model that assumes that the plasma above the polar caps becomes optically thick at frequencies that approach the electron cyclotron frequency w H . These authors find that t i w H = 100 keV gives the best fi t to their data, which corresponds to a magnetic field strength of I O l 3 gauss. We note that this estimate is model dependent since it requires assumptions regarding the spatial energy release distribution of the accreted protons in the polar hot spot, as well as the radiative heat transfer characteristics of this region. Also, the predictions of this model on the energy dependence of the pulse profile are contradicted by our present data.” I n the following we report on the discovery of a strong line feature in the Her X-l spectrum at 53 keV, which we interpret as cyclotron emission. The corresponding magnetic field is 4.6 x 10I2 gauss.