CHANG-ES. VII. MAGNETIC OUTFLOWS FROM THE VIRGO CLUSTER GALAXY NGC 4388
CHANG-ES. VII. MAGNETIC OUTFLOWS FROM THE VIRGO CLUSTER GALAXY NGC 4388
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DOI：
10.3847/0004-637x/824/1/30
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发表时间：
2016-04
期刊：
影响因子：
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通讯作者：
A. Damas-Segovia;R. Beck;B. Vollmer;T. Wiegert;M. Krause;J. Irwin;M. Weżgowiec;Jiang-Tao Li;R. Dettmar;J. English;Q. Wang
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作者：
A. Damas-Segovia;R. Beck;B. Vollmer;T. Wiegert;M. Krause;J. Irwin;M. Weżgowiec;Jiang-Tao Li;R. Dettmar;J. English;Q. Wang
我们研究了冲击波压力对拥有射电晕和强核外流的星系的有序磁场的影响。在Chang-es EVLA计划中，获得了处女座星系NGC4388的总射电强度和偏振强度的新射电图像。达到的前所未有的噪音水平使我们能够探测到有序磁场的显著新特征。核外流从中心向晕延伸至约5kpc，并在空间上与X射线发射相关。这是第一次检测到南方的外流。在两个旋臂的上方和下方，我们发现了延伸的极化发射斑点，其中有一个有序的磁场垂直于圆盘。这些区域的宇宙射线电子(CRE)的同步辐射寿命产生了平均流出速度为，这与银河系风的假设相一致。NGC4388中观测到的极化晕特征的对称性排除了星系团内介质(ICM)的冲压对晕气体的压缩。晕压力和ICM ram压力之间的平衡假设给出了ICM密度的估计，它与从X射线观测得到的ICM密度和最近的Planck Sunyaev-Zel‘dovich测量结果是一致的。因此，探测到星系团星系周围微弱的射电晕可以用来估计ICM ram的压强。
We investigate the effects of ram pressure on the ordered magnetic field of a galaxy hosting a radio halo and strong nuclear outflows. New radio images in total and polarized intensity of the edge-on Virgo galaxy NGC 4388 were obtained within the CHANG-ES EVLA project. The unprecedented noise level reached allows us to detect striking new features of the ordered magnetic field. The nuclear outflow extends far into the halo to about 5 kpc from the center and is spatially correlated with the and X-ray emission. For the first time, the southern outflow is detected. Above and below both spiral arms we find extended blobs of polarized emission with an ordered field oriented perpendicular to the disk. The synchrotron lifetime of the cosmic-ray electrons (CREs) in these regions yields a mean outflow velocity of , in agreement with a galactic wind scenario. The observed symmetry of the polarized halo features in NGC 4388 excludes a compression of the halo gas by the ram pressure of the intracluster medium (ICM). The assumption of equilibrium between the halo pressure and the ICM ram pressure yields an estimate of the ICM density that is consistent with both the ICM density derived from X-ray observations and the recent Planck Sunyaev–Zel’dovich measurements. The detection of a faint radio halo around cluster galaxies could thus be used for an estimate of ICM ram pressure.