激波、塞弗茨和SNR联系：圆规星系的钱德拉观测
Shocks, Seyferts and the SNR connection: a Chandra observation of the Circinus galaxy
摘要：
我们分析了最近的（D=4兆秒差距）塞弗特2活跃星系，Circinus的新的钱德拉观测，并将它们与预先存在的无线电，红外和光学数据相匹配，以研究千秒差距尺度的排放。圆规座的接近使我们能够观察到射电叶结构的惊人细节，首次揭示了X射线和射电中的边缘增亮发射。在考虑了各种其他可能的情况下，我们表明，这种扩展的发射在圆规是最有可能造成的射流驱动的外流，这是驱动壳的强烈冲击气体到晕的宿主星系。在本文中，我们分别估计W和E壳的马赫数M=2.7-3.6和M=2.8-5.3。我们推导出W壳层和E壳层的温度分别为0.74（+0.06，-0.05）keV和0.8-1.8 keV，膨胀速度为~900-950 km/s。我们估计，形成这两个壳层的总能量（热能和动能）约为2 × 10^55尔格，它们的年龄约为10^6年。比较这些结果与我们以前获得的半人马座A，NGC 3801和Mrk 6，我们表明，这些参数的规模约与父活动星系核的无线电功率。圆规座的X射线和边缘增亮射电辐射之间的空间重合类似于某些SNR激波的形态。这种平行现象在活动星系核中被认为是存在的，但以前从未被观察到。我们调查这两种类型的系统可能有什么共同的潜在机制，认为在Circinus中，壳的边缘增亮可能是由冲击压缩引起的B场增强引起的，但不排除一些局部粒子加速。这些结果可以外推到其他低功耗系统，特别是那些晚型主机。
英文摘要：
We analyse new Chandra observations of the nearest (D=4 Mpc) Seyfert 2 active galaxy, Circinus, and match them to pre-existing radio, infrared and optical data to study the kpc-scale emission. The proximity of Circinus allows us to observe in striking detail the structure of the radio lobes, revealing for the first time edge-brightened emission both in X-rays and radio. After considering various other possible scenarios, we show that this extended emission in Circinus is most likely caused by a jet-driven outflow, which is driving shells of strongly shocked gas into the halo of the host galaxy. In this context, we estimate Mach numbers M=2.7-3.6 and M=2.8-5.3 for the W and E shells respectively. We derive temperatures of 0.74 (+0.06, -0.05) keV and 0.8-1.8 keV for the W and E shells, and an expansion velocity of ~900-950 km/s. We estimate that the total energy (thermal and kinetic) involved in creating both shells is ~2x10^55 erg, and their age is ~10^6 years. Comparing these results with those we previously obtained for Centaurus A, NGC 3801 and Mrk 6, we show that these parameters scale approximately with the radio power of the parent AGN. The spatial coincidence between the X-ray and edge-brightened radio emission in Circinus resembles the morphology of some SNR shocks. This parallel has been expected for AGN, but has never been observed before. We investigate what underlying mechanisms both types of systems may have in common, arguing that, in Circinus, the edge-brightening in the shells may be accounted for by a B field enhancement caused by shock compression, but do not preclude some local particle acceleration. These results can be extrapolated to other low-power systems, particularly those with late type hosts.
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