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arXiv 2407.08616astro-ph.GA
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GA-NIFS:利用JWST/NIRSpec研究红移z=9.11的MACS1149-JD1中并合、恒星形成与化学增丰的相互作用

GA-NIFS: the interplay between merger, star formation and chemical enrichment in MACS1149-JD1 at z=9.11 with JWST/NIRSpec

Cosimo Marconcini, Francesco D'Eugenio, Roberto Maiolino, Santiago Arribas, Andrew J. Bunker, Stefano Carniani, Stephane Charlot, Michele Perna, Bruno Rodriguez… 展开作者

Cosimo Marconcini, Francesco D'Eugenio, Roberto Maiolino, Santiago Arribas, Andrew J. Bunker, Stefano Carniani, Stephane Charlot, Michele Perna, Bruno Rodriguez Del Pino, Hannah Ubler, Chris J. Willott, Torsten Boker, Giovanni Cresci, Mirko Curti, Gareth C. Jones, Isabella Lamperti, Eleonora Parlanti, Giacomo Venturi

AI总结:

本研究通过JWST/NIRSpec观测红移z≈9.11的透镜星系MACS1149-JD1,解析其气体与恒星性质梯度,发现并合事件驱动恒星形成暴,排除旋转盘与强AGN假说,为高红移星系演化提供观测约束。

摘要:

作为GA-NIFS项目的一部分,我们展示了红移z≈9.11的透镜星系MACS1149-JD1的JWST/NIRSpec积分场光谱观测结果。观测数据同时通过G395H光栅(分辨率R≈2700)和棱镜(分辨率R≈100)获取。该目标呈现出一个拉长的主紫外亮团,以及一个在投影距离2千秒差距处被连续辐射探测到的次级成分。\nR2700分辨率的数据追踪了两个成分之间电离气体的形态-运动学特征,显示出主要由[O III]5007谱线示踪的拉长发射结构。我们空间分辨出[O II]3726,3729、[O III]4959,5007以及[O III]4363谱线,借此绘制出电子密度(nₑ≈1.0×10³ cm⁻³)、温度(Tₑ≈1.6×10⁴ K)以及直接法气相金属丰度(相对太阳为-1.2至-0.7 dex)的空间分布。\n对棱镜数据开展的空间分辨全光谱模拟表明,两个成分之间存在南北向的气体金属丰度与恒星年龄梯度。我们以3σ置信度发现气相金属丰度与恒星形成率密度存在空间分辨的反相关关系,这一现象可能由气体流入驱动,进而增强了JD1的恒星形成活动。我们采用对高红移敏感的诊断图,排除了主成分中存在强活动星系核(AGN)的可能性。\n这些发现明确表明该星系存在两个截然不同的恒星族群,其中大部分质量归因于一次早期的恒星形成暴,这与此前研究的结论一致。我们不支持MACS1149-JD1具有旋转盘结构的猜想,更倾向于认为一次并合事件导致了两个独立区域近期的恒星形成暴,这一结论得到了[O III]5007/Hβ高比值、电离气体速度弥散以及气相金属丰度特征的支撑。

英文摘要:

We present JWST/NIRSpec integral-field spectroscopy observations of the z ~ 9.11 lensed galaxy MACS1149-JD1, as part of the GA-NIFS programme. The data was obtained with both the G395H grating (R~ 2700) and the prism (R~ 100). This target shows a main elongated UV-bright clump and a secondary component detected in continuum emission at a projected distance of 2 kpc. The R2700 data trace the ionised-gas morpho-kinematics in between the two components, showing an elongated emission mainly traced by [O III]5007. We spatially resolve [O II]3726,3729, [O III]4959,5007, and [O III]4363, which enable us to map the electron density (ne ~ 1.0 x 103 cm-3), temperature (Te ~ 1.6 x 104 K), and direct-method gas-phase metallicity (-1.2 to -0.7 dex solar). A spatially resolved full-spectrum modelling of the prism indicates a north-south gas metallicity and stellar age gradient between the two components. We found 3-sigma evidence of a spatially resolved anti-correlation of the gas-phase metallicity and the star formation rate density, which is likely driven by gas inflows, enhancing the star formation in JD1. We employ high-z sensitive diagnostic diagrams to rule out the presence of a strong AGN in the main component. These findings show the unambiguous presence of two distinct stellar populations, with the majority of the mass ascribed to an old star formation burst, as suggested by previous works. We disfavour the possibility of a rotating-disc nature for MACS1149-JD1; we favour a merger event that has led to a recent burst of star formation in two separate regions, as supported by high values of [O III]5007/Hbeta, ionised gas velocity dispersion, and gas-phase metallicity.

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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