论文标题
NGC628（M74）的热磁光晕
Hot magnetic halo of NGC628 (M74)
论文作者
论文摘要
在观察到的几个螺旋星系中，发现了大规模有序的磁场（所谓的磁臂）。解释之一是磁重新连接的作用，这导致了磁场的较高顺序。由于它同时将磁场的能量转换为周围环境的热能，因此磁重新连接已被视为星际培养基的加热机理多年。直到最近，还没有发现这种现象的明确观察证据。我们在无线电和X射线数据中搜索可能通过磁性重新连接效应的气体加热特征，以示出螺旋星系NGC628（M74），它呈现出明显的磁臂和垂直磁场的证据。磁盘和光晕发射的温度和热能密度也得出了螺旋和磁性臂中磁场的强度和能量密度，以及磁盘发射的温度和热能密度。在磁性臂的区域中，磁场的高阶和较低的能量密度比在恒星螺旋臂中发现。整个磁盘中，热气的全球温度大致恒定。这些发现与为Starburst Galaxy M83获得的发现的比较表明，NGC628的光环中可能存在磁重新连接加热。 NGC628中磁场和热气体性能的联合分析也为可能与伴随星系的潮汐相互作用提供了线索。
In several spiral galaxies that are observed face-on, large-scale ordered magnetic fields (the so-called magnetic arms) were found. One of the explanations was the action of the magnetic reconnection, which leads to a higher ordering of the magnetic fields. Because it simultaneously converts the energy of the magnetic fields into thermal energy of the surroundings, magnetic reconnection has been considered as a heating mechanism of the interstellar medium for many years. Until recently, no clear observational evidence for this phenomenon was found. We search for possible signatures of gas heating by magnetic reconnection effects in the radio and X-ray data for the face-on spiral galaxy NGC628 (M74), which presents pronounced magnetic arms and evidence for vertical magnetic fields. The strengths and energy densities of the magnetic field in the spiral and magnetic arms were derived, as were the temperatures and thermal energy densities of the hot gas, for the disk and halo emission. In the regions of magnetic arms, higher order and lower energy density of the magnetic field is found than in the stellar spiral arms. The global temperature of the hot gas is roughly constant throughout the disk. The comparison of the findings with those obtained for the starburst galaxy M83 suggests that magnetic reconnection heating may be present in the halo of NGC628. The joint analysis of the properties of the magnetic fields and the hot gas in NGC628 also provided clues for possible tidal interaction with the companion galaxy.
