A detailed study is presented of the counterrotating model (CRM) for electrovacuum stationary axially symmetric relativistic thin disks of infinite extension without radial stress, in the case when the eigenvalues of the energy-momentum tensor of the disk are real quantities, so that there is not heat flow. We find a general constraint over the counterrotating tangential velocities needed to cast the surface energy-momentum tensor of the disk as the superposition of two counterrotating charged dust fluids. We then show that, in some cases, this constraint can be satisfied if we take the two counterrotating tangential velocities as equal and opposite or by taking the two counterrotating streams as circulating along electro-geodesics. However, we show that, in general, it is not possible to take the two counterrotating fluids as circulating along electro-geodesics nor take the two counterrotating tangential velocities as equal and opposite. A simple family of models of counterrotating charged disks based on the Kerr-Newman solution are considered where we obtain some disks with a CRM well behaved. We also show that the disks constructed from the Kerr-Newman solution can be interpreted, for all the values of parameters, as a matter distribution with currents and purely azimuthal pressure without heat flow. The models are constructed using the well-known "displace, cut and reflect" method extended to solutions of vacuum Einstein-Maxwell equations. We obtain, in all the cases, counterrotating Kerr-Newman disks that are in agreement with all the energy conditions.
Symmetries of asymptotically flat electrovacuum spacetimes and radiation
利用Bondi-Sachs-van der Burg形式研究了与渐近平坦性相容并允许引力和电磁辐射的对称性。它表明，在轴对称的电真空时空中，其中至少局部存在一个光滑的零无穷在彭罗斯的意义上，唯一的第二个允许的对称性是平移对称或助推对称。平移不变的时空，通常沿着对称轴有一个直的“宇宙弦”，是无辐射的，尽管它们可以有一个非零的新闻功能。助推旋转对称时空是辐射性的。它们描述了"均匀加速的带电粒子"或黑洞，它们通常也可以旋转-轴向和额外的Killing矢量不假设是超曲面正交的。得到了引力和电磁新闻函数的一般泛函形式，以及零无穷远处渐近平坦boost-rotation对称时空的质量和总质量的一般泛函形式.即使在超曲面正交Killing矢量的真空助推旋转对称时空中，质量的表达式也是新的。在附录中出现的一些错误在以前的作品进行了更正。
The collisional Penrose process received much attention when Banados, Silk and West (BSW) pointed out the possibility of test-particle collisions with arbitrarily high center-of-mass energy in the vicinity of the horizon of an extremally rotating black hole. However, the energy that can be extracted from the black hole in this promising, if simplified, scenario, called the BSW effect, turned out to be subject to unconditional upper bounds. And although such bounds were not found for the electrostatic variant of the process, this version is also astrophysically unfeasible, since it requires a m…
Non-Monotonic Enhancement of the Magnetic Penrose Process in Kerr-Bertotti-Robinson Spacetime and its Implication for Electron Acceleration
National University of Uzbekistan（乌兹别克斯坦国立大学）；Institute of Fundamental and Applied Research, National Research University TIIAME（塔什干国立研究大学基础与应用研究所）；Institute for Theoretical Physics and Cosmology, Zhejiang University of Technology（浙江工业大学理论物理与宇宙学研究所）；Department of Physics, School of Advanced Sciences, Vellore Institute of Technology（维洛尔理工学院高级科学学院物理系）；University of Tashkent for Applied Sciences（塔什干应用科学大学）；Department of Physics, Hemvati Nandan Bahuguna Garhwal Central University（赫姆瓦蒂·南丹·巴胡加纳加尔瓦尔中央大学物理系）
Kerr-Bertotti-Robinson 空间中磁 Penrose 过程的非单调增强效应，揭示了电子加速至 $10^{15}\,\mathrm{eV}$ 的潜力，并通过辐射损失降至 TeV 级。
