DESI 主巡天 DR1 中的“叉”形几何：目标选择对星系演化研究的影响
The "Fork" Geometry in the DESI Main Survey DR1: Implications of Target Selection for Galaxy Evolution Studies
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中文总结 AI 辅助
本文研究 DESI DR1 中星系分布的“叉”形几何，发现其源于星系双峰性与巡天选择效应共同作用，并评估各目标类别影响，提出减少偏差的观测建议。
中文摘要 AI 辅助
暗能量光谱仪（DESI）主巡天数据发布 1（DR1）提供了可观测宇宙大部分区域内星系和类星体前所未有的光谱视图。然而，该巡天依赖于示踪体的目标选择策略引入了复杂的观测选择效应，强烈影响了星系在红移-光度平面上的表观分布。在本工作中，我们研究了 DESI DR1 中观测到的特征性“叉”形几何的起源，并表明观测到的分布与一种解释一致，即它源于星系内在双峰性和巡天红移依赖的选择函数的共同作用。我们表明，将主要星系种群分开的观测到的低密度区不仅受到物理绿谷的影响，还受到巡天选择效应的影响，因为它进一步受到星等极限、表面亮度选择和结构不完整性的塑造。利用 DESI DR1 光谱以及 Legacy Survey 测光数据，我们分析了 BGS、LRG、ELG 和 QSO 目标类别在产生观测分布中的作用，并评估了它们对光度函数测量的影响。我们的结果表明，目标选择和观测偏差都显著影响了观测到的星系分布以及从中推断出的演化趋势。我们总结了旨在最小化这些影响并使 DESI 能够进行更稳健的星系演化研究的实际观测注意事项。
英文摘要
The Dark Energy Spectroscopic Instrument (DESI) Main Survey Data Release 1 (DR1) provides an unprecedented spectroscopic view of galaxies and quasars across a large fraction of the observable Universe. However, the survey's tracer-dependent targeting strategy introduces complex observational selection effects that strongly influence the apparent distribution of galaxies in the redshift-luminosity plane. In this work, we investigate the origin of the characteristic "fork" geometry observed in DESI DR1 and show that the observed distribution is consistent with an interpretation in which it arises from the combined action of intrinsic galaxy bimodality and the survey's redshift-dependent selection function. We show that the observed underdensity separating the dominant galaxy populations is influenced not only by the physical Green Valley but also by survey selection effects, since it is further shaped by magnitude limits, surface-brightness selection, and structural incompleteness. Using DESI DR1 spectroscopy together with Legacy Survey photometry, we analyze the roles of the BGS, LRG, ELG, and QSO target classes in producing the observed distribution and assess their impact on luminosity-function measurements. Our results indicate that both target selection and observational biases significantly affect the observed galaxy distribution and the evolutionary trends inferred from it. We summarize practical observational considerations aimed at minimizing these effects and enabling more robust studies of galaxy evolution with DESI.
发表机构
- Instituto de Astronomía y Meteorología, CUCEI, Universidad de Guadalajara（瓜达拉哈拉大学天文与气象研究所）
- Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto（波尔图大学太空天体物理与科学研究所）
- Institute of Astrophysics, Facultad de Ciencias Exactas, Universidad Andrés Bello（安德烈斯贝略大学精确科学学院天体物理研究所）
- Gemini Observatory, NSF NOIRLab（双子座天文台美国国家光学红外天文研究实验室）
- Universidad Nacional de Córdoba（科尔多瓦国立大学）
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