DESI DR1亮星系巡天中星系属性的环境依赖性：z < 0.55处的恒星形成、形态与活动星系核活动
Environmental dependence of galaxy properties in the DESI DR1 Bright Galaxy Survey: Star formation, morphology, and AGN activity at z < 0.55
浏览论文内容
中文总结 AI 辅助
该研究基于DESI DR1亮星系巡天数据，分析z<0.55星系的恒星形成率、形态、AGN占比的环境依赖性，揭示该趋势由卫星星系占比而非内禀抑制主导的核心结论。
中文摘要 AI 辅助
我们利用暗能量光谱仪（DESI）第1批数据发布（DR1）中0.05 < z < 0.55范围内，星系团与星系群（暗晕质量对数log(M_h/M_⊙) ≥ 12.5）中约140万个BGS_BRIGHT星系，研究星系属性的环境依赖性。基于限幅BGS_BRIGHT样本（r < 19.5）与扩展的基于暗晕的星系群表，我们在恒星质量对数log(M_*/M_⊙) = 9.0-12.0、暗晕质量对数log(M_h/M_⊙) = 12.5-15.0的范围内，分析比恒星形成率（sSFR）、塞斯克指数（Sersic index）与活动星系核（AGN）占比对暗晕质量的依赖关系。中位sSFR随暗晕质量增大而降低，但该趋势主要由卫星星系占比上升驱动，而非单个星系受到更强的抑制；在固定恒星质量与暗晕质量下，卫星星系的中位sSFR低于中心星系，在中等恒星质量区间该差异最为明显。环境趋势显现的恒星质量阈值从z ~ 0.4时的log(M_*/M_⊙) ~ 11，偏移至z ~ 0.1时的~10，该偏移部分对应巡天恒星质量完备限的提升。固定恒星质量与红移下，平均塞斯克指数仅随暗晕质量弱增（从场星系到星系团的中位Δlog(n) ≈ 0.05）。在发射线探测到的星系（所有4条BPT线信噪比S/N > 3）中，AGN总占比随恒星质量单调上升；固定恒星质量下，赛弗特星系（Seyfert）占比无显著环境趋势（仅在唯一样本充足的高质量区间，场星系与星系团的差异≤3σ），低电离核发射线区星系（LINER）占比亦无明确环境趋势。本研究最可靠的结果是星系属性的相对环境排序，及其分解为内禀抑制与组分（卫星星系占比）效应的机制。
英文摘要
We present the environmental dependence of galaxy properties using $\sim$1.4 million BGS_BRIGHT galaxies in groups and clusters ($\log(M_h/M_\odot) \geq 12.5$) from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 at $0.05 < z < 0.55$. Using the magnitude-limited BGS_BRIGHT sample ($r < 19.5$) and the extended halo-based group catalogue, we examine how specific star formation rate (sSFR), Sersic index, and active galactic nucleus (AGN) fraction depend on halo mass across stellar masses $\log(M_*/M_\odot) = 9.0$-$12.0$ and halo masses $\log(M_h/M_\odot) = 12.5$-$15.0$. The median sSFR decreases with increasing halo mass, but much of this trend is driven by the rising satellite fraction rather than stronger suppression of individual galaxies. Satellites show lower median sSFR than centrals at fixed stellar mass and halo mass, most clearly at intermediate stellar masses. The stellar mass threshold at which the environmental trend becomes apparent shifts from $\log(M_*/M_\odot) \sim 11$ at $z \sim 0.4$ to $\sim 10$ at $z \sim 0.1$, a shift that partly tracks the survey's rising stellar-mass completeness limit. The mean Sersic index increases only weakly with halo mass (median $Δ\log(n) \approx 0.05$ from field to cluster at fixed stellar mass and redshift). Among emission-line-detected galaxies (S/N $> 3$ in all four BPT lines), the combined AGN fraction increases monotonically with stellar mass. At fixed stellar mass, the Seyfert fraction shows no significant environmental trend (consistent with flat; field-to-cluster differences $\lesssim 3σ$ in the only well-populated high-mass bin), and the LINER fraction likewise shows no clear environmental trend. The most robust outcome of this work is the relative environmental ordering of galaxy properties and its decomposition into intrinsic suppression and compositional (satellite fraction) effects.
