JWST/NIRSpec揭示拥有活动星系核（AGN）的矮星系中多样的核环境
JWST/NIRSpec Reveals Diverse Nuclear Environments in Dwarf Galaxies Hosting AGN
- Research Center for Space and Cosmic Evolution, Ehime University（爱媛大学宇宙演化研究中心）
- Department of Astronomy, The University of Texas at Austin（德克萨斯大学奥斯汀分校天文学系）
- Cosmic Frontier Center, The University of Texas at Austin（德克萨斯大学奥斯汀分校宇宙前沿中心）
- Department of Physics and Astronomy, University of California, Riverside（加州大学河滨分校物理与天文系）
- Department of Physics, Texas State University（德州州立大学物理系）
- Department of Physics and Astronomy, George Mason University（乔治梅森大学物理与天文系）
- Ehime University（爱媛大学）
- Division of Astronomy and Astrophysics, University of California, Los Angeles（加州大学洛杉矶分校天文与天体物理系）
- IPAC, MC 320-6, Caltech（加州理工学院IPAC）
- Hiroshima University（广岛大学）
- Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）
- Instituto de Astrofísica de Canarias（加那利群岛天体物理学研究所）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究利用JWST/NIRSpec观测4个矮星系，探测到100余条发射线及多样核环境，发现热H₂气体质量、发射结构等存在差异，印证旋转曲线多样性问题。
中文摘要 AI 辅助
在ΛCDM宇宙学框架下，矮星系被认为在所有红移处主导星系的数量密度。因此，研究这类星系中的活动星系核（AGN），包括表征其局部环境和发射特性，对于全面认识AGN种群及其对宿主星系的影响至关重要。为此，我们呈现了JWST/NIRSpec积分场单元（IFU）对4个有AGN活动证据的矮星系（恒星质量M⋆<10^9.5 M☉）的观测结果。利用JWST提供的分辨率和灵敏度提升，我们研究了这些矮星系中心千秒差距范围内的发射特征。我们的发现包括在样本中探测到100余条发射线，其中包含电离势大于300 eV的冕线。核光谱显示出多样的发射特征：2个星系中，我们测量到热尘埃对红外连续谱的强贡献；3个星系的核区100秒差距范围内同时探测到多环芳烃（PAH）和冕线发射。我们估算样本中所有星系在300秒差距范围内的热H₂气体质量为1-20 M☉，其激发同时涉及热激发和非热激发。最后，空间流量图显示所有观测气体相的发射结构各不相同，从围绕核的径向对称结构到拉长的 plume（羽流）；运动学图还显示，尽管所有星系均为孤立星系，但每个星系都有独特的速度结构，这印证了旋转曲线多样性问题——模拟与观测之间长期存在的张力。这些结果表明，拥有AGN的矮星系中存在独特且多样的核环境。
英文摘要
Dwarf galaxies, in the $Λ$CDM framework, are expected to dominate the galaxy number density at all redshifts. As such, studying AGN in these systems, including characterizing their local environments and emission properties, is essential in obtaining a comprehensive view of the AGN population and their influence on their host galaxy. To this end, we present JWST/NIRSpec IFU observations of four dwarf galaxies (M$_\star<$10$^{9.5}\;$M$_\odot$) with evidence of AGN activity. Utilizing the improvements in resolution and sensitivity offered by JWST, we investigate the emission features of the central kiloparsec of these dwarfs. Our findings include the detection of over 100 emission lines across our sample, including coronal lines with ionization potentials greater than 300 eV. The nuclear spectra show diverse emission features. In two galaxies, we measure strong contributions from hot dust to the infrared continuum. We also detect both PAH and coronal line emission within 100 parsecs of the nuclei in three galaxies. We estimate the hot H$_2$ gas mass to be between 1--20 M$_\odot$ within 300 pc across our sample, where both thermal and non-thermal excitation are involved. Lastly, spatial flux maps reveal varied emission structures across all observed gas phases, ranging from radial symmetry around the nucleus to elongated plumes. Kinematic maps also show each galaxy has unique velocity structures despite all being isolated, affirming the diversity of rotation curves problem, a long standing tension between simulations and observations. These results showcase the unique and varied nuclear environments that can be found in dwarf galaxies hosting AGN.
