Magnetic fields are amplified as a consequence of galaxy formation and turbulence-driven dynamos. Galaxy mergers can potentially amplify the magnetic fields from their progenitors, making the magnetic fields dynamically important. However, the effect of mergers on magnetic fields is still poorly understood. We use thermal polarized emission observations to trace the magnetic fields in the molecular disk of the nearest radio active galaxy, Centaurus A, which is thought to be the remnant of a merger. Here, we detect that the magnetic field orientations in the plane of the sky tightly follow the ~3.0 kpc-scale molecular warped disk. Our simple regular large-scale axisymmetric spiral magnetic field model can explain, to some extent, the averaged magnetic field orientations across the disk projected on the sky. Our observations also suggest the presence of small-scale turbulent fields, whose relative strengths increase with velocity dispersion and column density. These results have strong implications for understanding the generation and role of magnetic fields in the formation of galaxies across cosmic time.

由于星系的形成和湍流驱动的发电机，磁场被放大。星系合并可能会放大其祖先的磁场，使磁场在动态上变得重要。然而，合并对磁场的影响仍然知之甚少。我们使用热极化发射观测来追踪最近的放射性星系半人马座 A 的分子盘中的磁场，半人马座 A 被认为是合并的残余物。在这里，我们检测到天空平面中的磁场方向紧紧地遵循~3.0 kpc 尺度的分子扭曲盘。我们简单的规则大尺度轴对称螺旋磁场模型可以在一定程度上解释投射在天空上的圆盘上的平均磁场方向。我们的观察还表明存在小尺度湍流场，其相对强度随着速度分散和柱密度的增加而增加。这些结果对于理解磁场在整个宇宙时间形成星系中的产生和作用具有重要意义。