[论文解读] First results from the JWST Early Release Science Program Q3D: Ionization cone, clumpy star formation and shocks in a $z=3$ extremely red quasar host

Andrey Vayner, Nadia L. Zakamska+26 more|arXiv (Cornell University)|Mar 13, 2023

Galaxies: Formation, Evolution, Phenomena被引用 5

一句话总结

利用詹姆斯·韦布空间望远镜/NIRSpec积分场单元（IFU）观测，本研究绘制了红移z=2.94的极红类星体宿主星系中的电离机制图谱，揭示了类星体驱动的外流在电离锥之外产生广角激波，星暴区域呈团块状且恒星形成速率达200 M⊙ yr⁻¹，以及极端的星际介质（ISM）条件（ne ≈ 3,000 cm⁻³，AV ≤ 3 mag）。在电离锥外检测到激波，证实了大张角风的存在，表明类星体反馈在宇宙正午时期具有广泛影响。

ABSTRACT

Massive galaxies formed most actively at redshifts $z=1-3$ during the period known as `cosmic noon.' Here we present an emission-line study of an extremely red quasar SDSSJ165202.64+172852.3 host galaxy at $z=2.94$, based on observations with the Near Infrared Spectrograph (NIRSpec) integral field unit (IFU) on board JWST. We use standard emission-line diagnostic ratios to map the sources of gas ionization across the host and a swarm of companion galaxies. The quasar dominates the photoionization, but we also discover shock-excited regions orthogonal to the ionization cone and the quasar-driven outflow. These shocks could be merger-induced or -- more likely, given the presence of a powerful galactic-scale quasar outflow -- these are signatures of wide-angle outflows that can reach parts of the galaxy that are not directly illuminated by the quasar. Finally, the kinematically narrow emission associated with the host galaxy presents as a collection of 1 kpc-scale clumps forming stars at a rate of at least 200 $M_{\odot}$ yr$^{-1}$. The ISM within these clumps shows high electron densities, reaching up to 3,000 cm$^{-3}$ with metallicities ranging from half to a third solar with a positive metallicity gradient and V band extinctions up to 3 magnitudes. The star formation conditions are far more extreme in these regions than in local star-forming galaxies but consistent with that of massive galaxies at cosmic noon. JWST observations reveal an archetypical rapidly forming massive galaxy undergoing a merger, a clumpy starburst, an episode of obscured near-Eddington quasar activity, and an extremely powerful quasar outflow simultaneously.

研究动机与目标

• 理解在宇宙正午（z ≈ 3）时期，大质量、高尘埃消光的类星体宿主星系中的电离机制。
• 研究类星体驱动外流在加热和电离宿主星系星际介质（ISM）中的作用。
• 表征团块状星暴区域的物理条件，包括电子密度、金属丰度和消光程度。
• 确定激波电离是否可在电离锥之外被探测到，从而揭示广角外流的几何结构。
• 评估类星体光致电离对延伸的Lyα亮斑及邻近星系的贡献程度。

提出的方法

• 利用JWST/NIRSpec积分场单元（IFU）光谱学技术，获取类星体宿主星系及其伴星的空间分辨发射线数据。
• 应用标准发射线诊断图（如[O III]/Hβ、[S II]/Hα）以区分光致电离、激波电离与星暴活动。
• 使用q3dfit软件对IFU数据立方体中的流体动力学与电离结构进行建模。
• 通过巴尔末减量（Hα/Hβ）校正Hα光度的尘埃消光，并推导恒星形成速率。
• 利用[O II]与[O III]线比值绘制金属丰度梯度，假设处于光致电离平衡状态。
• 将空间分辨的线比与模拟结果对比，推断外流几何结构与激波特性的特征。

Figure 1: On the left, we present line-integrated [O III ] 5007 Å flux in units of $\times 10^{-17}$ erg s -1 cm -2 Å -1 arcsec -2 , in the middle, we present the radial velocity centroid ( $v_{50}$ ) map in units of km s -1 and on the right the velocity dispersion maps for each detected kinematic c

实验结果

研究问题

• RQ1 类星体宿主星系及其伴星不同区域的主导电离机制是什么？
• RQ2 电离锥之外是否可探测到激波电离区域？这些区域揭示了怎样的外流几何结构？
• RQ3 宿主星系中团块状星暴区域的物理条件（密度、金属丰度、消光）如何？
• RQ4 类星体光致电离对邻近星系与潮汐结构的延伸影响有多大？
• RQ5 类星体驱动外流如何影响宿主星系的ISM与恒星形成活动？

主要发现

• 在电离锥垂直方向检测到外锥区域的激波电离区域，表明类星体外流具有大张角，其影响显著超出直接视线方向。
• 宿主星系至少包含九个尺度为1 kpc的星暴团块，总恒星形成速率不低于200 M⊙ yr⁻¹，符合宇宙正午时期的极端条件特征。
• 星暴团块中的电子密度高达3,000 cm⁻³，显著高于本地星暴星系，V波段消光程度可达3个星等。
• 东北方向星暴区域的氧丰度为太阳值的二分之一至三分之一，且从中心向外呈现正向金属丰度梯度。
• 大多数区域以光致电离为主导，但在电离锥外检测到激波电离，证实类星体风可影响未被类星体直接照亮的气体。
• 类星体光致电离的影响延伸至邻近星系与潮汐尾，支持其在驱动类似类星体周围延伸Lyα亮斑中的关键作用。

Figure 2: A color composite of ionized gas emission in the J1652 quasar host galaxy and the immediate environment. [O III ] is assigned to blue, H $\alpha$ is assigned to green, [N II ] is assigned to red and [S II ] is assigned to orange. Bar on the left represents 1 arcsecond, and the quasar is lo