DESI 亮红星系周围方位各向异性 MgII 吸收的证据
Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies
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中文总结 AI 辅助
该研究利用 DESI DR1 的亮红星系和背景类星体光谱，通过强制测量方法，测量 MgII 等效宽度场，发现其全角度分布随半径和红移有变化，且存在方位各向异性，为 LRG 周围气体结构可测提供证据。
中文摘要 AI 辅助
我们使用暗能量光谱巡天（DESI）的第一次数据发布（DR1）中的亮红星系（LRG）和背景类星体光谱，测量了大质量静止星系周围 MgII 等效宽度场随投影半径和相对于投影主轴方位角的变化。我们的强制测量方法为每对 LRG - 类星体对分配一个 MgII 双峰窗口等效宽度，包括未单独检测到吸收体的光谱，并减去从相同归一化类星体光谱测量的红移匹配随机控制信号。全角度分布在 $r_\text{p}=0.01$ - $1.0$ 固有百万秒差距内平滑下降，并且在 $0.4<z_{\rm LRG}<0.75$ 时比在 $0.75<z_{\rm LRG}<1.1$ 时显示出更强的内部吸收。叠加在这种径向和红移依赖性上，在 $r_\text{p}\simeq30$ - $80$ 千秒差距处，靠近 LRG 主轴的视线相对于次轴显示出增强的吸收。对于完整的 $0.4<z_{\rm LRG}<1.1$ 样本，在 $r_\text{p}=0.03$ - $0.077$ 百万秒差距上的综合基准主轴减去次轴差值为 $0.184\pm0.075$ 埃，位置角随机化概率 $p = 0.013$。红移分割显示各向异性幅度没有显著演化，尽管内部等效宽度分布本身会演化。DESI DR1 的测量为 LRG 周围含 MgII 的冷/暖气体的局部主轴增强提供了证据，表明在大质量静止晕以及恒星形成系统中方位角的星系晕圈结构是可测量的。
英文摘要
We use luminous red galaxies (LRGs) and background quasar spectra from DESI DR1 to measure the mean MgII equivalent width around massive quiescent galaxies as a function of projected radius and azimuth relative to the projected major axis. Our forced-measurement approach assigns a MgII doublet-window EW to every LRG-quasar pair, including spectra without individually detected absorbers, and subtracts a redshift-matched random-control signal measured from the same normalized quasar spectra. The all-angle profile declines smoothly over $r_p=0.01$-$1.0$ proper Mpc and shows stronger inner absorption at $0.4<z_{\rm LRG}<0.75$ than at $0.75<z_{\rm LRG}<1.1$. Superposed on this radial and redshift dependence, sightlines near the LRG major axis show enhanced absorption relative to the minor axis at $r_p\simeq30$-$80$ kpc. For the full $0.4<z_{\rm LRG}<1.1$ sample, the integrated fiducial major-minus-minor difference over $r_p=0.03$-$0.077$ Mpc is $0.184\pm0.075$ Angstrom, with a position-angle randomization probability $p=0.013$. The redshift split shows no significant evolution in the anisotropy amplitude, even though the inner EW profile itself evolves. Our results provide evidence for a localized major-axis enhancement of MgII-bearing cool/warm gas around LRGs, showing that azimuthal CGM structure is measurable in massive quiescent halos as well as in star-forming systems.
