High-resolution X-ray spectroscopy and imaging of the nuclear outflow of the starburst galaxy NGC 253
High-resolution X-ray spectroscopy and imaging of the nuclear outflow of the starburst galaxy NGC 253
复制标题
星暴星系 NGC 253 核流出的高分辨率 X 射线光谱和成像
DOI：
10.1051/0004-6361:20066340
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发表时间：
2006
影响因子：
6.5
通讯作者：
U. Leicester
中科院分区：
文献类型：
--
作者：
M. Bauer;W. Pietsch;G. Trinchieri;D. Breitschwerdt;M. Ehle;A. F. M. F. E. Physik;I. ;Institut fuer Astronomie der Universitaet Wien;E. Centre;Esa;D. PhysicsAstronomy;U. Leicester
目标。使用 XMM-Newton 数据，我们研究了附近星暴星系 NGC 253 在 X 射线中的核流出，包括其形态和沿流出的光谱变化。方法。我们分析了 XMM-Newton RGS 光谱、交叉色散方向的 RGS 亮度分布、窄带 RGS 和 EPIC 图像，以及核区和 NGC 253 流出物的 EPIC PN 亮度分布。结果。我们沿着 NGC 253 的流出检测到多种发射线。这包括 Si、Mg、Ne 和 O 的类 He 离子以及它们处于下一个更高电离态的相应离子。此外，$\ion{Fe}{xvii}$ 和 $\ion{Fe}{xviii}$ 的转变也很突出。从沿流出流的线比率得出的温度范围为 0.21 ± 0.01 至 0.79 ± 0.06 keV，并且 $\ion{Fe}{xvii}$ 线的比率表明主要是碰撞电离等离子体。此外，我们在 $\ion{Fe}{xvii}$ 线比中看到重组或离子化不足的等离子体的迹象。核区域的导出电子密度为 0.106 ± 0.018 cm -3 ，最接近中心的流出区域的电子密度为 0.025 ± 0.003 cm -3 。 $\ion{O}{viii}$ 线能量中的 RGS 图像清楚地显示了沿东南短轴延伸至约 750 pc 的外流形态，而由于银盘的严重吸收，在 $\ion{O}{viii}$ 中看不到外流的西北部分。这是首次直接检测到热风流体。 Chandra 和 XMM-Newton EPIC 观测中的临边增亮仅在包含 $\ion{Fe}{xvii}$ 线 (550-750 eV) 的能量范围内可见。在 400 至 2000 eV 之间的所有其他能量范围内，无法检测到肢体变亮的明显证据。
Aims. Using XMM-Newton data, we have studied the nuclear outflow of the nearby starburst galaxy NGC 253 in X-rays with respect to its morphology and to spectral variations along the outflow. Methods. We analysed XMM-Newton RGS spectra, RGS brightness profiles in cross-dispersion direction, narrow-band RGS and EPIC images, and EPIC PN brightness profiles of the nuclear region and of the outflow from NGC 253. Results. We detect a diversity of emission lines along the outflow of NGC 253. This includes the He-like ions of Si, Mg, Ne, and O and their corresponding ions in the next higher ionisation state. Additionally transitions from $\ion{Fe}{xvii}$ and $\ion{Fe}{xviii}$ are prominent. The derived temperatures from line ratios along the outflow range from 0.21 ± 0.01 to 0.79 ± 0.06 keV, and the ratio of $\ion{Fe}{xvii}$ lines indicates a predominantly collisionally ionised plasma. Additionally, we see indications of either a recombining or an underionised plasma in the $\ion{Fe}{xvii}$ line ratio. Derived electron densities are 0.106 ± 0.018 cm -3 for the nuclear region and 0.025 ± 0.003 cm -3 for the outflow region closest to the centre. The RGS image in the $\ion{O}{viii}$ line energy clearly shows the morphology of an outflow extending out to ~750 pc along the southeast minor axis, while the northwest part of the outflow is not seen in $\ion{O}{viii}$ due to the heavy absorption by the galactic disc. This is the first time that the hot wind fluid has been detected directly. The limb brightening in Chandra and XMM-Newton EPIC observations is only seen in the energy range that contains the $\ion{Fe}{xvii}$ lines (550-750 eV). In all other energy ranges between 400 and 2000 eV, no clear evidence of limb brightening could be detected.