Probing multi-phase outflows and AGN feedback in compact radio galaxies: the case of PKS B1934-63
Probing multi-phase outflows and AGN feedback in compact radio galaxies: the case of PKS B1934-63
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探测紧凑射电星系中的多相流出和 AGN 反馈：PKS B1934-63 的案例
DOI：
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发表时间：
2018
影响因子：
6.5
通讯作者：
J. Holt
中科院分区：
文献类型：
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作者：
F. Santoro;M. Rose;R. Morganti;C. Tadhunter;T. Oosterloo;J. Holt
年轻的AGN无线电对于我们理解AGN反馈的许多仍然有争议的方面是至关重要的。本文利用X射线射电观测对致密的峰值射电星系PKS B1934-63中的星际介质(ISM)进行了研究。大多数热电离气体存在于半径约为200pC的环核圆盘内，很可能构成中央黑洞供应的气库。另一方面，我们发现了一个双锥形的热电离气体流出，其半径估计为59±12pC。这与射电源的径向范围相匹配，并表明外流是由喷流驱动的。由于数据的波长覆盖率很高，我们可以利用跨极光线技术来估计热电离气体的密度，我们发现外流气体的密度非常高，最高可达logNe(cm−3)≃5.5。估计的质量流出率很低(Ṁ=10−3−10−1M⊙yr−1)，活动星系核反馈的运行效率相对较低(Ė/LBOL∼10−4−10−3%)。此外，光学和近红外线比表明，射电源的扩张驱动了快速激波(速度为≳500公里S−1)，这些激波电离并加速了外流气体。与其他承载热电离气体流出的紧凑、尖峰频谱射电源的特性不同，我们没有发现运动扰动或流出气体的迹象，这些气体处于比热电离气体更低的相中。我们认为这是由于我们的源的年龄较小，因此是由于AGN-ISM相互作用的近期性质，并表明在流出的物质中形成了冷气体，而PKS B1934-63的激波电离流出的气体没有足够的时间冷却并在较冷的相中积累。文献中其他小型和年轻射电源的多阶段外流也支持这一设想。
Young radio AGN are pivotal for our understanding of many of the still-debated aspects of AGN feedback. In this paper we present a study of the interstellar medium (ISM) in the compact, peaked-spectrum radio galaxy PKS B1934-63 using X-shooter observations. Most of the warm ionized gas resides within a circum-nuclear disk with a radius of about 200 pc that is likely to constitute the gas reservoir from which the central black hole feeds. On the other hand, we find a biconical outflow of warm ionized gas with an estimated radius of 59 ± 12 pc. This matches the radial extent of the radio source and suggests that the outflow is jet driven. Thanks to the superior wavelength coverage of the data, we can estimate the density of the warm ionized gas using the trans-auroral line technique, and we find that the outflowing gas has remarkably high density, up to log ne (cm−3) ≃ 5.5. The estimated mass outflow rate is low (Ṁ = 10−3 −10−1 M⊙ yr−1), and the AGN feedback operates at relatively low efficiency (Ė/Lbol ∼ 10−4−10−3%). In addition, optical and near-IR line ratios show that the expansion of the radio source drives fast shocks (with velocities vs ≳ 500 km s−1) that ionize and accelerate the outflowing gas. At odds with the properties of other compact, peaked-spectrum radio sources hosting warm ionized gas outflows, we do not find signs of kinematically disturbed or outflowing gas in phases colder than the warm ionized gas. We argue that this is due to the young age of our source and thus to the recent nature of the AGN-ISM interaction, and suggest that cold gas forms within the outflowing material and the shock-ionized outflowing gas of PKS B1934-63 did not have enough time to cool down and accumulate in a colder phase. This scenario is also supported by the multi-phase outflows of other compact and young radio sources in the literature.