AI 中文总结
本研究分析了红移0.87641处的部分莱曼限吸收体，发现其与两个近邻星系的属性及位置匹配，该吸收体可能是气体流入星系的信号，相关情景在宇宙学模拟框架下展开讨论。
AI 中文摘要
我们对在背景类星体LBQS 0107-0235的HST/COS光谱中探测到的红移z=0.87641处的一个部分莱曼限系统开展分析。该吸收体呈现出简单的运动学结构，金属线与氢原子莱曼系列吸收可由单一成分很好地描述。光电离建模得出气体金属丰度为太阳的十分之一，氢数密度n_H≈8.5×10^-4 cm^-3（log₁₀(n_H/cm^-3)≈-3.1）。在吸收体的红移处，VLT/MUSE数据显示有两个星系（G1和G2），其归一化撞击参数分别为ρ/R_vir≈0.9，与吸收体的速度差分别为|Δv|=18 km s^-1和99 km s^-1。两个星系均为旋转盘，恒星质量分别为M_*≈6×10^9 M_⊙和≈2.2×10^10 M_⊙；它们1亿年平均恒星形成率分别为≈2.5 M_⊙ yr^-1和≈2.2 M_⊙ yr^-1，不过瞬时恒星形成率显示G2处于恒星形成主序上，G1高于主序，在该红移处处于活跃恒星形成状态。吸收体的位置非常接近两个星系的投影长轴，其取向、运动学及亚太阳金属丰度（log₁₀(Z/Z_⊙)=-1.05）与吸收体追踪亚太阳金属丰度的流入流一致，但不能排除星系-星系相互作用起源的可能。我们在冷模式吸积及晕质量M_h≲10^12 M_⊙的星系周围CGM气体流的宇宙学模拟框架下讨论这些情景。
英文摘要
We present an analysis of a partial Lyman limit system at z = 0.87641 detected in the HST/COS spectrum of the background quasar LBQS 0107-0235. The absorber exhibits a simple kinematic structure, with the metal-lines and the H I Lyman-series absorption well described by a single component. Photoionization modeling yields a gas metallicity of one-tenth solar and a hydrogen number density of n_H \approx 8.5 \times 10^{-4} cm^{-3} (log_{10}(n_H/cm^{-3}) \approx -3.1). At the absorber redshift, the VLT/MUSE data show two galaxies (G1 and G2) at normalized impact parameters of ρ/R_{vir} \approx 0.9 and velocity separations of |Δv| = 18 and 99 km s^{-1}, respectively, from the absorber. Both galaxies have rotating disks with stellar masses of M_* \approx 6 \times 10^9 and \approx 2.2 \times 10^{10} M_{\odot}. Their 100-Myr-averaged star formation rates are \approx 2.5 and \approx 2.2 M_{\odot} yr^{-1}, though their instantaneous rates place G2 on the star-forming main sequence and G1 above it, which is actively star-forming at this redshift. The absorber is positioned very close to the projected major axis of both galaxies. The absorber's orientation, kinematics, and sub-solar metallicity (log_{10}(Z/Z_{\odot}) = -1.05) are consistent with the absorption tracing a sub-solar metallicity inflowing stream, though a galaxy-galaxy interaction origin cannot be excluded. We discuss these scenarios in the context of cosmological simulations of cold-mode accretion and CGM gas flows around galaxies with halos of mass M_h \lesssim 10^{12} M_{\odot}.
Comments29 pages, 14 figures. Accepted for publication in the Astrophysical Journal (ApJ)
