标题： M31中无线电发射形状对暗物质湮灭的限制 显示英文标题

标题： Limits on Dark Matter Annihilation from the Shape of Radio Emission in M31

摘要： 具有良好动机的暗物质模型通常会在星系中产生电子和正电子群体，这些电子和正电子通过暗物质湮灭产生——通常与伽马射线有关。 当它们通过星系磁场扩散时，这些 $e^\pm$ 会产生同步辐射射电发射。 该信号的强度和形态取决于 $e^\pm$ 所通过的星际介质的特性。 利用对仙女座星系（M31）的观测来构建气体、磁场和星光的模型，我们通过 3.6 厘米射电发射的形态对暗物质湮灭到 $b\bar{b}$ 进行了限制。 由于 M31 中心的发射信号对扩散系数和暗物质分布非常敏感，我们根据中心附近 $0.9-6.9$ 千秒差距区域的微分通量设定了我们的限制。 我们排除了质量范围$10-500$GeV 内的湮灭截面$\gtrsim 3 \times 10^{-25}$cm$^3$/s，在$20-40$GeV 处的最大灵敏度为$7\times 10^{-26}$cm$^3$/s。 尽管这些限制比之前对 M31 的研究结果弱，但它们对扩散系数的变化是稳健的。 显示英文摘要

摘要： Well-motivated models of dark matter often result in a population of electrons and positrons within galaxies produced through dark matter annihilation -- usually in association with gamma rays. As they diffuse through galactic magnetic fields, these $e^\pm$ produce synchrotron radio emission. The intensity and morphology of this signal depends on the properties of the interstellar medium through which the $e^\pm$ propagate. Using observations of the Andromeda Galaxy (M31) to construct a model of the gas, magnetic fields, and starlight, we set constraints on dark matter annihilation to $b\bar{b}$ using the morphology of 3.6 cm radio emission. As the emission signal at the center of M31 is very sensitive to the diffusion coefficient and dark matter profile, we base our limits on the differential flux in the region between $0.9-6.9$ kpc from the center. We exclude annihilation cross sections $\gtrsim 3 \times 10^{-25}$ cm$^3$/s in the mass range $10-500$ GeV, with a maximum sensitivity of $7\times 10^{-26}$ cm$^3$/s at $20-40$ GeV. Though these limits are weaker than those found in previous studies of M31, they are robust to variations of the diffusion coefficient.