Dwarf galaxies are dark matter-dominated and therefore promising targets for the search for weakly interacting massive particles (WIMPs), which are well-known candidates for dark matter. Annihilation of WIMPs produce ultra-relativistic cosmic-ray electrons and positrons that emit synchrotron radiation in the presence of magnetic fields. For typical magnetic field strengths (few $\mu $G) and $\mathcal O$(GeV--TeV) WIMP masses, this emission peaks at hundreds of MHz. Here, we use the non-detection of 150-MHz radio continuum emission from the dwarf spheroidal galaxy Canes Venatici I with the LOw-Frequency ARray (LOFAR) to derive constraints on the annihilation cross section of WIMPs into primary electron-positron and other fundamental particle-antiparticle pairs. Our main underlying assumption is that the transport of the cosmic rays can be described by the diffusion approximation, thus requiring a non-zero magnetic field strength with small-scale structure. In particular, by adopting magnetic field strengths of $\mathcal O(1\,\mu$G) and diffusion coefficients $\sim 10^{27}~\rm cm^2\,s^{-1}$, we obtain limits that are comparable with those set by \emph{Fermi} Large Area Telescope using gamma-ray observations of this particular galaxy. Assuming s-wave annihilation and WIMPs making up 100 per cent of the DM density, our benchmark limits exclude several thermal WIMP realisations in the $[2,20]$-GeV mass range. We caution, however, that our limits for the cross section are subject to enormous uncertainties which we also quantitatively assess. In particular, variations on the propagation parameters or on the DM halo can shift our limits up by several orders of magnitude (in the pessimistic scenario).

中文翻译：

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使用 LOFAR 的 Canes Venatici I 暗物质湮灭的无线电限制†

矮星系是暗物质主导的，因此是寻找弱相互作用大质量粒子 (WIMP) 的有希望的目标，这些粒子是众所周知的暗物质候选者。WIMP 的湮灭产生超相对论宇宙射线电子和正电子，它们在磁场存在的情况下发射同步辐射。对于典型的磁场强度 (几 $\mu $G) 和 $\mathcal O$(GeV--TeV) WIMP 质量，这种发射峰值为数百 MHz。在这里，我们使用低频阵列 (LOFAR) 未检测到来自矮椭球星系 Canes Venatici I 的 150-MHz 无线电连续谱发射，推导出对 WIMPs 湮灭截面的约束为初级电子 - 正电子和其他基本粒子-反粒子对。我们的主要基本假设是宇宙射线的传输可以通过扩散近似来描述，因此需要具有小尺度结构的非零磁场强度。特别地，通过采用 $\mathcal O(1\,\mu$G) 的磁场强度和扩散系数 $\sim 10^{27}~\rm cm^2\,s^{-1}$，我们使用对这个特定星系的伽马射线观测，获得与\emph{Fermi} 大面积望远镜设定的极限相当的极限。假设 s 波湮灭和 WIMP 占 DM 密度的 100%，我们的基准限制排除了 $[2,20]$-GeV 质量范围内的几个热 WIMP 实现。然而，我们警告说，我们对横截面的限制受到我们也定量评估的巨大不确定性的影响。特别是，