标题： 使用FAST对仙女座星系M31的新连续波观测 显示英文标题

标题： New Continuum Observations of the Andromeda galaxy M31 with FAST

摘要： 我们展示了利用500米口径球面射电望远镜（FAST）在1.248 GHz观测的M31新总强度图像，其角分辨率为4弧分，灵敏度约为16毫开尔文。 新的FAST图像由于其对大尺度结构的高灵敏度，明显揭示了环外的弱发射。 我们推导出宇宙射线电子的标度长度为2.7千秒差距，并通过比较4.8 GHz处的标度长度发现宇宙射线电子主要通过扩散传播。 总强度的光谱指数沿环变化，这可以归因于同步辐射发射光谱的变化。 这种变化可能是由环上恒星形成率的变化引起的。 我们发现非热辐射的方位角分布可以通过具有环上变化倾角的大尺度轴对称磁场来解释，表明M31中复杂的磁场配置。 显示英文摘要

摘要： We present a new total intensity image of M31 at 1.248 GHz, observed with the Five-hundred-meter Aperture Spherical radio telescope (FAST) with an angular resolution of 4 arcmin and a sensitivity of about 16 mK. The new FAST image clearly reveals weak emission outside the ring due to its high sensitivity on large-scale structures. We derive a scale length of 2.7 kpc for the cosmic ray electrons and find that the cosmic ray electrons propagate mainly through diffusion by comparing the scale length at 4.8 GHz. The spectral index of the total intensity varies along the ring, which can be attributed to the variation of the spectra of synchrotron emission. This variation is likely caused by the change of star formation rates along the ring. We find that the azimuthal profile of the non-thermal emission can be interpreted by an axisymmetric large-scale magnetic field with varying pitch angle along the ring, indicating a complicated magnetic field configuration in M31.