发表机构
Universität Heidelberg; Max-Planck-Institut für Astronomie; Max-Planck-Institut für Radioastronomie; Max-Planck-Institut für Astrophysik（海德堡大学; 马克斯·普朗克天文学研究所; 马克斯·普朗克射电天文研究所; 马克斯·普朗克天体物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用TNG50模拟和偏振辐射传输，评估了从法拉第旋转推断高红移透镜星系磁场强度的方法，发现差分法拉第旋转是稳健探针，但CLASS B1152+199的大ΔRM在模拟星系中较罕见。
AI 中文摘要
对CLASS B1152+199（红移z=0.439）透镜星系中法拉第旋转的观测表明，高效的发电机机制在该时期已经放大了星系磁场。我们评估了该方法推导磁场强度的可靠性，以及观测到类似大的法拉第旋转差异的可能性。我们从TNG50宇宙学磁流体动力学模拟中选取了64个恒星形成盘状星系，这些星系在质量和红移上与CLASS B1152+199匹配，并使用POLARIS进行偏振辐射传输和后续的RM合成进行前向建模。TNG50预测单个星系的特征大尺度场强度B$_0$为1.9-15.6微高斯，而组合样本给出B$_0$=10.3微高斯。从合成观测推断的场强度B$_{obs}$通常在因子三内恢复B$_0$。B$_{obs}$对假定的磁场几何形状的依赖较弱，而星系倾角和波束去极化影响更强。从RM合成恢复的差分旋转测量与直接积分的值保持相关性，尽管波束去极化系统性地降低了其幅度。只有1.41%的直接积分视线对重现了CLASS B1152+199观测到的ΔRM=1040±60弧度每平方米，对于与观测到的2.6和6.5千秒差距相当的星系中心距离处的视线，这一比例增加到3.16%。因此，引力透镜源的差分法拉第旋转为大尺度磁场提供了稳健的探针，而CLASS B1152+199的大ΔRM在所考虑的TNG50模拟星系中相对罕见。
英文摘要
Observations of Faraday rotation in the lensing galaxy of CLASS B1152+199 at z = 0.439 suggest that efficient dynamo mechanisms had already amplified galactic magnetic fields by this epoch. We assess the reliability of this method for deriving magnetic field strengths and the likelihood of observing similarly large Faraday rotation differences. We select 64 star-forming disk galaxies from the TNG50 cosmological magnetohydrodynamical simulation, matched to CLASS B1152+199 in mass and redshift, and forward model them using polarized radiative transfer with POLARIS and subsequent RM synthesis. TNG50 predicts characteristic large-scale field strengths of B$_0$ = 1.9-15.6 $μ$G for individual galaxies, while the combined sample yields B$_0$ = 10.3 $μ$G. Field strengths B$_{obs}$ inferred from the synthetic observations generally recover B$_0$ within a factor of three. B$_{obs}$ depends only weakly on the assumed magnetic field geometry, whereas galaxy inclination and beam depolarization have stronger effects. The differential rotation measure recovered from RM synthesis remains correlated with the directly integrated value, although beam depolarization systematically reduces its magnitude. Only 1.41% of directly integrated sightline pairs reproduce the observed $Δ$RM = 1040 $\pm$ 60 rad m$^{-2}$ of CLASS B1152+199, increasing to 3.16% for sightlines at galactocentric distances comparable to the observed 2.6 and 6.5 kpc. Differential Faraday rotation of gravitationally lensed sources therefore provides a robust probe of large-scale magnetic fields, while the large $Δ$RM of CLASS B1152+199 is relatively rare among the considered TNG50 analog galaxies.
Comments17 pages, 13 figures
