发表机构
Hamburger Sternwarte, Universität Hamburg; INAF - Istituto di Radioastronomia; Dipartimento di Fisica e Astronomia, Università di Bologna; ASTRON, Netherlands Institute for Radio Astronomy; INAF - Osservatorio Astronomico di Cagliari; Aix Marseille Univ, CNRS, CNES, LAM; Department of Astronomy and Astrophysics, University of Chicago（汉堡天文台，汉堡大学; 意大利国家天体物理研究所射电天文研究所; 博洛尼亚大学物理与天文系; 荷兰射电天文研究所; 意大利国家天体物理研究所卡利亚里天文台; 艾克斯-马赛大学，法国国家科学研究中心，法国国家空间研究中心，拉格朗日实验室; 芝加哥大学天文学与天体物理学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究利用MeerKAT偏振观测，通过RM合成表征室女星系团中M49区域的磁场，发现尾流中RM散射增强及磁场包裹效应，为星系运动湍流建模提供依据。
AI 中文摘要
大尺度磁场渗透在星系团的星系团内介质（ICM）中。理解这些磁场有助于洞察宇宙磁场的起源以及星系团星系与ICM的相互作用。利用MeerKAT对室女星系团的观测，作为ViCTORIA项目的一部分，我们通过旋转测量（RM）合成来探测磁场。本工作的目的是表征室女星系团中下落中的星系群M49内部及其周围的磁场。我们将通过M49对偏振发射和法拉第旋转的印记来探测其与周围介质的相互作用。我们使用全偏振的L波段MeerKAT数据，这些数据由ViCTORIA MeerKAT巡天（ViMS）流程校准，该流程专为室女星系团中天区的校准、成像、马赛克拼接和RM合成而设计，以实现总强度和偏振发射的高保真重建。我们通过计算RM分布来分析星系团的背景源，以探测磁场潜在的局部变化。在最终的偏振图像中，由四个45分钟的指向组成，我们达到了$23.3 \mu \textrm{Jy/beam}$的噪声水平。我们在M49周围约$2.5\\, \textrm{deg}^2$的区域探测到101个背景源，对应源密度为40个源/$\textrm{deg}^2$。在整个$112\\, \textrm{deg}^2$的室女星系团观测中，这意味着总共约4000个偏振源。在M49中，我们发现结构化的弥散偏振发射沿总强度射电尾的方向延伸。源上边缘更高的偏振分数表明存在磁场包裹效应。在M49周围，我们发现M49尾流中的RM散射（在$3.8\sigma$水平）大于其前方区域。这可以为星系运动产生的湍流建模提供信息。
英文摘要
Large-scale magnetic fields permeate the Intracluster Medium (ICM) of galaxy clusters. Understanding these fields gives an insight into the origin of cosmic magnetic fields and the interaction of cluster galaxies with the ICM. Using MeerKAT observations of the Virgo cluster as part of the ViCTORIA project, we probe magnetic fields via Rotation Measure (RM) synthesis. The aim of this work is to characterise the magnetic fields in and around the infalling group M49 in the Virgo cluster. We will probe the interaction of M49 with its surrounding medium through its imprint on the polarised emission and Faraday rotation. We use L-band MeerKAT data in full polarisation calibrated with the ViCTORIA MeerKAT Survey (ViMS) pipeline, which is designed for the calibration, imaging, mosaicking and RM Synthesis of the fields in the Virgo cluster, to achieve high-fidelity reconstruction of, both, total intensity and polarised emission. We analyse the background sources of the cluster for potential local changes in the magnetic field, by calculating the RM distribution. In the final polarised image, consisting of four pointings of 45 min, we reach a noise level of $23.3 μ\textrm{Jy/beam}$. We detect 101 background sources in the $\sim 2.5\, \textrm{deg}^2$ region around M49, corresponding to a source density of 40 sources/$ \textrm{deg}^2$. Across the $112\, \textrm{deg}^2$ observations of the Virgo cluster, this implies a total number of 4000 polarised sources. In M49 we find structured, diffuse polarised emission extending in the direction of the total intensity radio tails. A higher polarisation fraction across the upper edge of the source indicates the effect of magnetic field draping. Around M49 we find a larger RM scatter (at $3.8σ$) in the wake of M49 compared to the region in front of it. This can inform the modelling of the turbulence created by galactic motions.
Comments20 pages, 20 figures, submitted to A&A
