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arXiv 2402.17875astro-ph.GA
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在 z=6.072 的强引力透镜星系空间分辨分析中脱颖而出(基于 JWST NIRCam)

Outshining in the Spatially Resolved Analysis of a Strongly-Lensed Galaxy at z=6.072 with JWST NIRCam

C. Giménez-Arteaga, S. Fujimoto, F. Valentino, G. B. Brammer, C. A. Mason, F. Rizzo, V. Rusakov, L. Colina, G. Prieto-Lyon, P. A. Oesch, D. Espada, K. E. Heintz… 展开作者

C. Giménez-Arteaga, S. Fujimoto, F. Valentino, G. B. Brammer, C. A. Mason, F. Rizzo, V. Rusakov, L. Colina, G. Prieto-Lyon, P. A. Oesch, D. Espada, K. E. Heintz, K. K. Knudsen, M. Dessauges-Zavadsky, N. Laporte, M. Lee, G. E. Magdis, Y. Ono, Y. Ao, M. Ouchi, K. Kohno, A. M. Koekemoer

AI总结:

基于JWST/NIRCam观测,对z=6.072强引力透镜星系进行~200pc尺度的空间分辨分析,发现逐像素方法能缓解发射线与连续谱简并,准确估计恒星质量,避免空间积分方法因年轻恒星突出发射导致的低估。

摘要:

我们展示了一个位于红移 z=6.072 处的强引力透镜、多重成像星系的 JWST/NIRCam 观测结果,该星系各处的引力放大因子 >~20。我们基于逐像素的 5 个 NIRCam 成像波段的 SED 建模,推断出在 ~200 pc 尺度上物理性质的空间分辨分析。我们发现年轻恒星被延伸的较老恒星族群所包围。通过将图像分析推断的 Hα+[NII] 和 [OIII]+Hβ 图谱与我们补充的 NIRSpec IFU 数据进行比较,我们发现这些发射线图谱的空间分布和强度与 IFU 测量结果一致。我们在空间积分测光数据上使用 Bagpipes 探索了不同的参数化 SFH 形式,发现双幂律星系形成历史(DPL)能检索出最接近空间分辨恒星质量估计的值,而其他 SFH 形式受年轻恒星主导的突出(outshining)发射影响,从而低估了恒星质量——高达 ~0.5 dex。另一方面,DPL 无法匹配 IFU 测得的发射线。此外,与空间分辨分析相比,在空间积分方法中,电离光子产生效率可能被高估了 ~0.15 dex。与 IFU 测量结果的一致性表明,逐像素方法可作为缓解发射线通量过剩与底层连续谱之间普遍简并性的一种途径,特别是在缺乏测光中带覆盖和/或 IFU 观测时。本研究强调,必须将星系作为其本身复杂的系统来研究,在可能的情况下解析其恒星族群,或使用更灵活的 SFH 参数化。这有助于我们应对推断高红移星系可靠恒星质量和电离光子产生效率的挑战,从而增进对星系演化早期阶段的理解。

英文摘要:

We present JWST/NIRCam observations of a strongly-lensed, multiply-imaged galaxy at $z=6.072$, with magnification factors >~20 across the galaxy. We perform a spatially-resolved analysis of the physical properties at scales of ~200 pc, inferred from SED modelling of 5 NIRCam imaging bands on a pixel-by-pixel basis. We find young stars surrounded by extended older stellar populations. By comparing H$α$+[NII] and [OIII]+H$β$ maps inferred from the image analysis with our additional NIRSpec IFU data, we find that the spatial distribution and strength of the line maps are in agreement with the IFU measurements. We explore different parametric SFH forms with Bagpipes on the spatially-integrated photometry, finding that a double power-law star formation history retrieves the closest value to the spatially-resolved stellar mass estimate, and other SFH forms suffer from the dominant outshining emission from the youngest stars, thus underestimating the stellar mass - up to ~0.5 dex-. On the other hand, the DPL cannot match the IFU measured emission lines. Additionally, the ionizing photon production efficiency may be overestimated in a spatially-integrated approach by ~0.15 dex, when compared to a spatially-resolved analysis. The agreement with the IFU measurements points towards the pixel-by-pixel approach as a way to mitigate the general degeneracy between the flux excess from emission lines and underlying continuum, especially when lacking photometric medium-band coverage and/or IFU observations. This study stresses the importance of studying galaxies as the complex systems that they are, resolving their stellar populations when possible, or using more flexible SFH parameterisations. This can aid our understanding of the early stages of galaxy evolution by addressing the challenge of inferring robust stellar masses and ionizing photon production efficiencies of high redshift galaxies.

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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