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arXiv 2312.04098astro-ph.GA
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揭示NGC1087中隐藏的棒状结构:利用MUSE/VLT、ALMA和JWST获得的运动学与测光证据

Unveiling a hidden bar-like structure in NGC1087: kinematic and photometric evidence using MUSE/VLT, ALMA and JWST

Carlos López-Cobá, Lihwai Lin, Sebastián F. Sánchez

AI总结:

本研究结合JWST、MUSE/VLT与ALMA数据,在NGC1087中发现隐藏的近红外棒状结构及其多相气体运动学扰动,并用分子气体流入解释其恒星形成。

摘要:

我们报告通过使用JWST近红外相机(NIRCam)在NGC1087中发现的一个暗弱非轴对称结构,并在恒星速度图、Hα和CO J=2→1速度场中观测到相应的运动学对应物,表现为椭圆形畸变。该结构在MUSE光学连续谱图像中并不明显,仅在近红外波段通过分别位于2 μm和3 μm的F200W与F300M滤光片得以显现。由于其拉长形态,该结构类似恒星棒,但与常规恒星棒存在显著差异。大部分近红外辐射集中在6角秒(约500 pc)范围内,最大延伸可达1.2 kpc。大尺度非圆运动的空间延伸与该棒重合,这无疑证实了NGC1087的引力势中存在非轴对称扰动。由于CO具有动力学冷的性质,椭圆形畸变在CO中比在Hα中更为显著。我们发现,包括恒星、电离气体和分子气体在内的所有相的运动学都可以由一个包含双对称扰动的模型同时描述;然而,我们也发现气体沿棒主轴流入的模型同样可能成立。此外,与之相关的分子质量流入率可以解释该棒中观测到的恒星形成率。这强化了棒是输运气体并触发恒星形成机制的观点。本工作利用迄今最精密的数据,增进了我们对星系中非轴对称性的理解。

英文摘要:

We report a faint non-axisymmetric structure in NGC\,1087 through the use of JWST Near Infrared Camera { (NIRCam)}, with an associated kinematic counterpart observed as an oval distortion in the stellar velocity map, \ha~and CO~$J=2\rightarrow1$ velocity fields. This structure is not evident in the MUSE optical continuum images but only revealed in the near-IR with the F200W and F300M band filters at $2μ$m and $3μ$m respectively. Due to its elongation, this structure resembles a stellar bar although with remarkable differences with respect to conventional stellar bars. Most of the near-IR emission is concentrated within $6\arcsec~\sim500$~pc with a maximum extension up to 1.2~kpc. The spatial extension of the large-scale non-circular motions is coincident with the bar, which undoubtedly confirms the presence of a non-axisymmetric perturbation in the potential of NGC\,1087. The oval distortion is enhanced in CO due to its dynamically cold nature rather than in \ha. We found that the kinematics in all phases including stellar, ionized and molecular, can be described simultaneously by a model containing a bisymmetric perturbation; however, we find that an inflow model of gas along the bar major axis is also likely. Furthermore the molecular mass inflow rate associated can explain the observed star formation rate in the bar. This reinforces the idea that bars are mechanisms for transporting gas and triggering star formation. This work contributes to our understanding of non-axisymmetry in galaxies using the most sophisticated data so far.

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