Compact objects such as neutron stars and white dwarfs can source axionlike particles and QCD axions due to $CP$-violating axion-fermion couplings. The magnitude of the axion field depends on the stellar density and on the strength of the axion-fermion couplings. We show that even $CP$-violating couplings one order of magnitude smaller than existing constraints source extended axion field configurations. For axionlike particles, the axion energy is comparable to the magnetic energy in neutron stars with inferred magnetic fields of the order of ${10}^{13}\mathrm{G}$ and exceeds by more than one order of magnitude the magnetic energy content of white dwarfs with inferred fields of the order of ${10}^4\mathrm{G}$. On the other hand, the energy stored in the QCD axion field is orders of magnitude lower due to the smallness of the predicted $CP$-violating couplings. It is shown that the sourced axion field can polarize the photons emitted from the stellar surface, and stimulate the production of photons with energies in the radio band.

中文翻译：

---

通过 CP 破坏耦合在致密恒星物质中获取轴子

中子星和白矮星等致密天体可以产生类轴子粒子和 QCD 轴子，因为$C磷$-破坏轴子-费米子耦合。轴子场的大小取决于恒星密度和轴子-费米子耦合的强度。我们证明即使$C磷$-比现有约束源小一个数量级的破坏耦合源扩展轴子场配置。对于轴子粒子，轴子能量与中子星中的磁能相当，推断磁场为${10}^{13}\mathrm{G}$并且超过白矮星的磁能含量一个数量级以上，推断磁场为${10}^4\mathrm{G}$。另一方面，由于预测的能量较小，QCD 轴子场中存储的能量要低几个数量级。$C磷$- 违反联轴器规定。结果表明，源轴子场可以偏振从恒星表面发射的光子，并刺激射电波段能量光子的产生。