AI 中文总结
NASIM 是一种自动化近红外处理管线，用于恢复 VISTA 数据中的低表面亮度结构，其表面亮度极限比 2MASS 深 67 倍，为研究星系外围和微弱宇宙提供了新窗口。
AI 中文摘要
星系的外围区域保留了其组装历史的化石记录，并且主要由老年恒星群体主导，这些恒星群体受到潮汐相互作用、吸积事件和环境过程的塑造。在近红外（NIR）波段，特别是 $K_s$ 波段，观测这些低表面亮度（LSB）区域，对于追踪演化恒星和最小化尘埃影响至关重要。然而，由于明亮且变化的天空背景和复杂的探测器系统效应，地面近红外对微弱延展结构的研究仍然具有挑战性。为了克服这些限制，我们开发了 NASIM，即近红外自动化低表面亮度处理管线（Near-infrared Automated low Surface brightness reduction In Maneage pipeline），这是一个完全自动化和可复现的框架，旨在恢复 VISTA/VIRCAM 数据中的微弱结构。利用 GNU 天文工具（Gnuastro），NASIM 校正了 VIRCAM 探测器上的大尺度平场模式和仪器特征，同时保留了在传统近红外处理中可能被强烈抑制的 LSB 发射。我们将 NASIM 应用于通过 KEDFS 计划获得的欧几里得深场南（Euclid Deep Field South）的 $K_s$ 波段成像，该区域也是 Rubin/LSST 和 Euclid 任务的关键目标区域。最终处理达到的表面亮度极限为 $\u03bc_{K_s} \simeq 27.7$ 星等每平方角秒，在 100 平方角秒范围内以 $3\sigma$ 测量，其表面亮度灵敏度比 2MASS 深约 67 倍，比 VHS 深约 11 倍。与公开可用的 VISTA 产品直接比较表明，NASIM 在不大幅牺牲致密源深度的情况下保留了弥散发射。这些结果为研究微弱的星系外围、LSB 星系和星系团内光打开了深近红外观测窗口，为未来研究微弱宇宙提供了可复现的地面基础。
英文摘要
The outskirts of galaxies retain fossil records of their assembly history and are dominated by old stellar populations shaped by tidal interactions, accretion events, and environmental processes. Observing these low-surface-brightness (LSB) regions in the near-infrared (NIR), particularly in the $K_s$ band, is crucial for tracing evolved stars and minimising the effects of dust. Yet, ground-based NIR studies of faint extended structures remain challenging because of the bright and variable sky background and complex detector systematics. To overcome these limitations, we developed NASIM, the Near-infrared Automated low Surface brightness reduction In Maneage pipeline, a fully automated and reproducible framework designed to recover faint structures in VISTA/VIRCAM data. Using GNU Astronomy Utilities (Gnuastro), NASIM corrects large-scale flat-field patterns and instrumental signatures across the VIRCAM detectors while preserving LSB emission that can be strongly suppressed in conventional NIR reductions. We apply NASIM to $K_s$-band imaging of the Euclid Deep Field South through the KEDFS programme, a key region also targeted by Rubin/LSST and Euclid. The final reduction reaches a surface-brightness limit of $μ_{K_s} \simeq 27.7$ mag arcsec$^{-2}$, measured at $3σ$ over 100 arcsec$^2$, approximately 67 times deeper than 2MASS and 11 times deeper than VHS in surface-brightness sensitivity. Direct comparisons with publicly available VISTA products show that NASIM preserves diffuse emission without substantially compromising compact-source depth. These results open a deep NIR view of faint galaxy outskirts, LSB galaxies, and intracluster light, providing a reproducible ground-based foundation for future studies of the faint Universe.
Comments6 pages, 3 figures. Proceedings IAU Symposium No. 403, The Hidden Beauty of the Galactic Outskirts, 2025
