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arXiv 2601.03339astro-ph.GA
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通过JWST边缘星系揭示早期薄盘组装

Early thin-disc assembly revealed by JWST edge-on galaxies

Kapteyn Astronomical Institute, University of Groningen(格罗宁根大学卡普坦天文研究所)

Marloes van Asselt, Francesca Rizzo, Luca Di Mascolo

AI总结:

研究利用JWST观测测量边缘星系盘厚度,发现盘高约1.6倍于本地单盘拟合结果,表明薄盘在z≈3时已存在,暗示厚盘通过动力加热逐步形成。

摘要:

星系盘的垂直结构对理解其形成和演化至关重要。近邻螺旋星系,包括银河系,可能包含薄和厚成分,这些成分可能源于早期湍流阶段或随后的动力加热。测量不同宇宙时间的盘厚度可直接检验这些情景。本文提出一种新的方法,通过拟合完整的三维模型并进行正向建模,以测量边缘星系的厚度,该方法考虑了偏离完美边缘取向的情况。应用该方法分析JWST对1<z<3的星系成像数据,发现中位数尺度高为z₀=0.25±0.14kpc,中位数比h_r/z₀=8.4±3.7。这些值与银河系和本地薄盘一致,表明本地星系单盘拟合得出的尺度高约为1.6倍。该结果表明薄盘在z≈3时已存在。进一步显示,厚盘贡献10%薄盘光度则可在本文数据中检测到,暗示任何厚盘必须较暗,支持厚盘在z<1时通过动力加热逐步形成的情景。

英文摘要:

The vertical structure of stellar discs provides key constraints on their formation and evolution. Nearby spirals, including the Milky Way, host thin and thick components that may arise either from an early turbulent phase or from the subsequent dynamical heating of an initially thin disc; measuring disc thickness across cosmic time therefore offers a direct test of these scenarios. We present a new methodology to measure the thickness of edge-on galaxies that explicitly accounts for departures from perfectly edge-on orientations by fitting a full three-dimensional model with forward modelling. This improves on traditional approaches that assume an inclination of $90^\circ$ and can bias thicknesses high. Applying the method to JWST imaging of galaxies at $1<z<3$ with stellar masses $\gtrsim 10^9~M_\odot$ from four major surveys, we measure a median scale height of $z_0 = 0.25\pm0.14$~kpc and a median ratio $h_r/z_0=8.4\pm3.7$. These values are consistent with the Milky Way and local thin discs, and indicate scale heights $\sim 1.6$ times smaller than those inferred for local galaxies from single-disc fits. This result implies that thin discs are already present at $z\sim3$. We further show that a thick disc contributing 10\% of the thin-disc luminosity would be detectable in the data considered in this work, implying that any thick disc present must be fainter and favouring a scenario in which thick discs build up progressively through dynamical heating at $z<1$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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