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arXiv 1503.04074astro-ph.HE
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PG1211 +143中磁驱动吸积盘风和超快流出

Magnetically-Driven Accretion-Disk Winds and Ultra-Fast Outflows in PG1211+143

Keigo Fukumura, Francesco Tombesi, Demosthenes Kazanas, Chris Shrader, Ehud Behar, Ioannis Contopoulos

摘要:

我们提出了一个磁流体动力学(MHD)吸积盘风的X射线电离的研究,努力约束的物理基础的高度电离的超快外流(UFO)推断的X射线吸收经常检测到的各种子类的塞弗特活动星系核(AGN)。我们的主要重点是表明,磁驱动的外流确实是物理上合理的候选人所观察到的外流占AGN的吸收特性,目前的X射线光谱观测。采用分层的MHD风穿过整个活动星系核吸积盘,我们计算了它的X射线电离和随后的X射线吸收线谱。假设一个适当的电离活动星系核谱,我们应用我们的MHD风模拟的吸收功能,在一个{ \it XMM-Newton}/EPIC谱的窄线Seyfert,\pg。通过对Fe K $α$跃迁的特征识别,我们发现该吸收体的特征电离参数为$\log (ξ_c [erg~cm~s$ ^{-1} $]) \simeq 5-6$,柱密度为$N_H \simeq 10^{23}$ cm $^{-2}$数量级,以特征速度$v_c/c \simeq 0.1-0.2$($c$为光速)流出.最佳拟合模型倾向于它的径向位置在$r_c \simeq 200 R_o$($R_o$是黑洞最里面的稳定圆形轨道),内风截断半径在$R_{\rm t} \simeq 30 R_o$。结果表明,K壳层的总体特征是\fexxv \占主导地位,\fexxvi \和弱电离铁的贡献很小,这与包括\pg在内的各种活动星系核中UFO的一系列早期分析结果一致.

英文摘要:

We present a study of X-ray ionization of magnetohydrodynamic (MHD) accretion-disk winds in an effort to constrain the physics underlying the highly-ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub-classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically-driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an {\it XMM-Newton}/EPIC spectrum of the narrow-line Seyfert, \pg. We find, through identifying the detected features with Fe K$α$ transitions, that the absorber has a characteristic ionization parameter of $\log (ξ_c [erg~cm~s$^{-1}$]) \simeq 5-6$ and a column density on the order of $N_H \simeq 10^{23}$ cm$^{-2}$, outflowing at a characteristic velocity of $v_c/c \simeq 0.1-0.2$ (where $c$ is the speed of light). The best-fit model favors its radial location at $r_c \simeq 200 R_o$ ($R_o$ is the black hole innermost stable circular orbit), with an inner wind truncation radius at $R_{\rm t} \simeq 30 R_o$. The overall K-shell feature in the data is suggested to be dominated by \fexxv\ with very little contribution from \fexxvi\ and weakly-ionized iron, which is in a good agreement with a series of earlier analysis of the UFOs in various AGNs including \pg.

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