Axion dark matter (DM) may convert to radio-frequency electromagnetic radiation in the strong magnetic fields around neutron stars. The radio signature of such a process would be an ultranarrow spectral peak at a frequency determined by the mass of the axion particle. We analyze data we collected from the Robert C. Byrd Green Bank Telescope in the $L$ band and the Effelsberg 100-m Telescope in the $L$ band and $S$ band from a number of sources expected to produce bright signals of axion-photon conversion, including the Galactic center of the Milky Way and the nearby isolated neutron stars RX J0720.4-3125 and RX J0806.4-4123. We find no evidence for axion DM and are able to set constraints on the existence of axion DM in the highly motivated mass range between $\sim 5$ and $11\mu \mathrm{eV}$ with the strongest constraints to date on axions in the $\sim 10–11\mu \mathrm{eV}$ range.

中文翻译：

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绿岸和埃菲尔斯堡射电望远镜在中子星磁层中寻找轴突暗物质转换

轴突暗物质（DM）可能在中子星周围的强磁场中转换为射频电磁辐射。这样的过程的无线电信号将是在由轴突颗粒的质量确定的频率处的超窄谱峰。我们分析了从罗伯特·C·伯德·格林银行望远镜收集到的数据$\mathrm{大号}$ 乐队和Effelsberg 100米望远镜 $\mathrm{大号}$ 乐队和 $\mathrm{小号}$该波段来自许多有望产生轴轴-光子转换信号的信号源，包括银河系的银河中心和附近的孤立中子星RX J0720.4-3125和RX J0806.4-4123。我们找不到轴力DM的证据，并且能够在高动力质量范围内对轴力DM的存在设置限制。$〜5$ 和 $11\mu \mathrm{电子伏特}$ 迄今为止，对轴的约束最强 $〜10–11\mu \mathrm{电子伏特}$ 范围。