arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0908.2985astro-ph.CO
收藏

宇宙射线和附近星暴星系NGC 253:II的磁场。磁场结构

Cosmic rays and the magnetic field in the nearby starburst galaxy NGC 253: II. The magnetic field structure

Volker Heesen, Marita Krause, Rainer Beck, Ralf-Jürgen Dettmar

摘要:

我们用D-配置的VLA和Effelsberg 100-m望远镜使用射电连续偏振测量法观测了NGC 253。将6.2 cm和3.6 cm处的观测结果结合起来计算RM分布并校正法拉第旋转。大尺度磁场由盘(r,phi)和晕(r,z)分量组成。盘分量可以被描述为轴对称的螺旋场,其指向内部,具有25+/-5度的螺距角,其相对于平面对称(偶宇称)。晕场显示了一个突出的X形中心的核心类似于其他边缘星系。我们提出了一个模型,其中晕场线是沿着一个锥与90 +/- 30度的开口角,并指向远离磁盘在北部和南部的晕(偶宇称)。X形晕场跟随着在H α和软X射线发射中看到的叶。发电机作用和盘风可以解释X形晕场。核恒星暴驱动的超级风可能会通过压缩膨胀的超级气泡的叶片来进一步放大和排列晕场。盘风是一个很有前途的候选人的起源气体的晕和驱逐小规模的螺旋领域所要求的有效发电机行动。

英文摘要:

(Shortened) We observed NGC 253 with the VLA in D-configuration and the Effelsberg 100-m telescope using radio continuum polarimetry. Observations at 6.2 cm and 3.6 cm were combined to calculate the RM distribution and to correct for Faraday rotation. The large-scale magnetic field consists of a disk (r, phi) and halo (r, z) component. The disk component can be described as an axisymmetric spiral field pointing inwards with a pitch angle of 25+/-5 degree which is symmetric with respect to the plane (even parity). The halo field shows a prominent X-shape centered on the nucleus similar to that of other edge-on galaxies. We propose a model where the halo field lines are along a cone with an opening angle of 90 +/- 30 degree and are pointing away from the disk in both the northern and southern halo (even parity). The X-shaped halo field follows the lobes seen in Halpha and soft X-ray emission. Dynamo action and a disk wind can explain the X-shaped halo field. The nuclear starburst-driven superwind may further amplify and align the halo field by compression of the lobes of the expanding superbubbles. The disk wind is a promising candidate for the origin of the gas in the halo and for the expulsion of small-scale helical fields as requested for efficient dynamo action.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑