[论文解读] Bubbles and outflows: the novel JWST/NIRSpec view of the z=1.59 obscured quasar XID2028

G. Cresci, G. Tozzi+21 more|arXiv (Cornell University)|Jan 26, 2023

Galaxies: Formation, Evolution, Phenomena被引用 6

一句话总结

利用詹姆斯·韦布空间望远镜/NIRSpec IFU观测，本研究揭示了红移z=1.59的遮蔽类星体XID2028中存在一个由喷流驱动的复杂膨胀气泡，其中低光度射电喷流在星系星际介质中膨胀形成一个高温、低表面亮度的气泡，并驱动了一道快速、延伸的电离喷流。数据证实存在多相喷流，总质量喷流速率为~110 M☉/yr，表明射电喷流在高红移AGN反馈中起着关键作用。

ABSTRACT

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, although direct observational evidence is still scarce and debated. Here we present Early Release Science JWST NIRSpec IFU observations of the z=1.59 prototypical obscured Active Galactic Nucleus (AGN) XID2028: This target represents a unique test case for studying quasar feedback at the peak epoch of AGN-galaxy co-evolution because extensive multi-wavelength coverage is available and a massive and extended outflow is detected in the ionised and molecular components. With the unprecedented sensitivity and spatial resolution of the JWST, the NIRSpec dataset reveals a wealth of structures in the ionised gas kinematics and morphology that were previously hidden in the seeing-limited ground-based data. In particular, we find evidence of an interaction between the interstellar medium of the galaxy and the quasar-driven outflow and radio jet that produces an expanding bubble from which the fast and extended wind detected in previous observations emerges. The new observations confirm the complex interplay between the AGN jet, wind and the interstellar medium of the host galaxy, highlighting the role of low-luminosity radio jets in AGN feedback. They also clearly show the new window that NIRSpec opens for detailed studies of feedback at high redshift.

研究动机与目标

• 研究在星系演化峰值时期，典型遮蔽AGN在z=1.59时类星体反馈的物理机制。
• 以前所未有的空间和光谱分辨率，解析电离、中性及分子喷流的运动学与形态结构。
• 确定低光度射电喷流在驱动和塑造宿主星系星际介质中喷流的作用。
• 量化电离、中性及分子气体相的能源学与质量喷流速率。
• 检验假设：喷流-ISM相互作用形成的膨胀气泡可同时驱动负反馈与正反馈。

提出的方法

• 利用詹姆斯·韦布空间望远镜/NIRSpec在近红外波段（1–5 μm）获取深度、空间分辨的IFU光谱，以绘制电离气体的运动学与形态。
• 采用三维辐射转移建模（MOKA^3D）模拟膨胀气泡与准直喷流的几何结构，并匹配观测到的运动学特征。
• 通过空间分辨光谱中的诊断线比值（如 [SII]/Hα、[OII]/Hβ）直接测量喷流中的消光与电子密度。
• 利用档案中的VLA 3 GHz数据交叉识别射电结构，将喷流发射与电离喷流形态相关联。
• 通过发射线的运动学分解并假设覆盖因子与电离分数，估算质量喷流速率。
• 将观测到的喷流能量学与理论反馈阈值进行比较，评估其抑制恒星形成潜力。

Figure 1: H $\beta$ (left panel) and H $\alpha$ (right panel) spectral region fit in $5\times 5$ NIRSpec spaxels centred on the QSO position. In the upper panels, the data are shown in black, and the best-fitting broad line region components (e.g. H $\beta$ , H $\alpha$ , and FeII) are shown in blue

实验结果

研究问题

• RQ1 XID2028中延伸电离喷流的起源与形态是什么？它与射电喷流有何关联？
• RQ2 电离、中性及分子气体相的运动学在反馈过程中如何相互关联？
• RQ3 低光度射电喷流在高红移遮蔽类星体中驱动大尺度喷流的贡献程度如何？
• RQ4 所有气体相的总质量喷流速率是多少？是否超过恒星形成速率？
• RQ5 观测到的膨胀气泡结构能否同时解释观测到的运动学特征与反馈效率？

主要发现

• NIRSpec数据揭示了电离气体中呈丝状、膨胀的气泡结构，边缘处发射增强，由低光度射电喷流与宿主星系星际介质相互作用驱动。
• 气泡的运动学最符合结合球形膨胀壳层与准直喷流的三维模型，证实喷流膨胀是喷流起源。
• 电离气体的质量喷流速率为6 ± 3 M☉/yr，动能功率约为~2 × 10^42 erg s⁻¹，表明反馈能量输入显著。
• 通过蓝移的NaID吸收推断出约30 M☉/yr的中性气体喷流速率，与先前基于MgII的估计一致。
• 电离、中性及分子相的总质量喷流速率达~110 M☉/yr，暗示气体耗尽 timescale 仅约30 Myr。
• 观测到的反馈几何结构支持负反馈（气体移除）与潜在正反馈（压缩诱导恒星形成），尽管未检测到恒星形成残留的Hα发射。

Figure 2: Representative examples of our multi-component fitting of H $\beta$ and [OIII] emission lines in single spaxels from three different regions of the galaxy, as marked with coloured crosses in Fig. 3 . From the top, the panels refer to a nuclear region spaxel, to a filament spaxel (see text)