发表机构
The Australian National University; University of Queensland; Macquarie University; University of New South Wales; University of California Observatories（澳大利亚国立大学; 昆士兰大学; 麦考瑞大学; 新南威尔士大学; 加州大学天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本试点研究利用 KOALA 积分场光谱观测三个近邻矮星系，分析其电离结构、恒星形成、金属丰度与运动学，发现其特性与本星系群矮星系高度相似，支持后者具有代表性。
AI 中文摘要
评估本星系群（Local Group）的宇宙学典型性，对于确定其矮星系族群是否具有代表性至关重要。为此，Delegate Survey 将本星系群类似环境中的矮星系作为观测目标，以进行系统性比较。作为 Delegate Survey 的试点研究，我们利用 AAT 上的 KOALA 仪器，对两个近邻星系群中的三个矮星系——GAMA 79098、GAMA 569709 和 HIPASS J1159-19 S2——获取了积分场光谱。这些星系以每空间像素（spaxel）1.25 角秒的空间采样进行成图，提供了恒星和电离气体两种成分的二维光谱覆盖。利用连续谱和发射线图，我们研究了每个系统的电离结构、恒星形成特性、金属丰度、恒星形成历史以及速度场。GAMA 79098 表现出与小麦哲伦云（SMC）密切类似的特性，在老年恒星族群之上叠加了持续的恒星形成，并具有中等程度的旋转支撑。GAMA 569709 类似于本星系群中的过渡型矮星系（如 NGC 147 和 NGC 185），主要呈现老年恒星族群。HIPASS J1159-19 S2 则以年轻恒星和强烈的恒星形成复合体为主导，与动力学上年轻、富含气体的星系群环境相符。两个 GAMA 矮星系在不确定度范围内遵循本星系群的恒星质量-金属丰度关系，而 HIPASS J1159-19 S2 在其恒星质量下显得金属丰度约高 0.5 dex。总体而言，这些矮星系的结构、化学和运动学特性与本星系群中的类似矮星系有显著重叠。
英文摘要
Assessing the cosmological typicality of the Local Group is crucial for establishing whether its dwarf galaxy population is representative. To this end, the Delegate Survey targets dwarf galaxies in Local Group analogues for systematic comparison. As a pilot study for the Delegate Survey, we obtained integral-field spectra of three dwarf galaxies, GAMA 79098, GAMA 569709, and HIPASS J1159-19 S2, in two nearby galaxy groups using the KOALA instrument on the AAT. The galaxies were mapped at a spatial sampling of 1.25 arcsec per spaxel, providing two-dimensional spectral coverage of both the stellar and ionised gas components. Using continuum and emission-line maps, we investigate the ionisation structure, star-forming properties, metallicity, star formation histories, and velocity fields of each system. GAMA 79098 exhibits properties closely analogous to the SMC, with ongoing star formation superimposed on an old stellar population and moderate rotational support. GAMA 569709 resembles transition-type Local Group (LG) dwarfs such as NGC 147 and NGC 185, showing predominantly an old stellar population. HIPASS J1159-19 S2 is dominated by young stars and intense star-forming complexes, consistent with a dynamically young, gas-rich galaxy group environment. The two GAMA dwarfs follow the LG stellar mass-metallicity relation within uncertainties, while HIPASS J1159-19 S2 appears approximately 0.5 dex more metal-rich for its stellar mass. Overall, the structural, chemical, and kinematic properties of these dwarfs overlap substantially with analogous LG dwarfs.
Comments18 pages, 11 figures
