利用POSSUM研究Abell 3667与Abell 3651之间星系团间纤维中的磁场
Investigating the magnetic field in the inter-cluster filament between Abell 3667 and Abell 3651 with POSSUM
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中文总结 AI 辅助
本研究利用POSSUM的RM网格，结合X射线分析的热电子密度先验，首次通过法拉第旋转测量约束了Abell 3667与Abell 3651间X射线探测到的星系团间纤维的磁场强度，凸显了精确建模银河系前景RM的重要性。
中文摘要 AI 辅助
本研究的目标是测量由扩展型伦琴望远镜阵列（eROSITA）在X射线波段新近探测到的显著星系团间纤维中的磁场。该纤维在天球上的投影跨度超过13百万秒差距（Mpc），连接着星系团Abell 3667与Abell 3651。我们采用宇宙磁场极化天空巡天（POSSUM）的旋转量（RM）网格，分离由该纤维磁化等离子体诱导的背景极化源的RM弥散与中值，进而推断该磁场的强度。该纤维区域由54个背景极化源采样。扣除前景银河系RM后，我们在纤维区域探测到边缘性残余RM弥散，其值为6.9±3.6 rad/m²，同时还探测到中值为6.3±1.3 rad/m²的相干残余RM信号。假设采用简化的单尺度磁场模型，并基于X射线分析得出的热电子密度分布采用合理先验，我们在95%置信度下将磁场强度约束在0.1-3.5微高斯（μG）范围内，根据假设的磁场相干尺度，优选值约为0.2-0.3 μG。不过，我们还发现该区域的银河系前景RM在与纤维自身尺度相当的角尺度上具有高度结构化，这是RM分析的主要不确定性来源。我们的结果提供了首个基于法拉第旋转测量的、针对单个X射线探测到的星系团间纤维的磁场约束，其场强与星系团桥及外围气体的理论预期一致。我们的分析还强调，精确建模银河系前景RM对未来利用POSSUM与平方公里阵列（SKA）开展的河外磁场研究至关重要。
英文摘要
[Abridged abstract] The objective of this study is to measure the magnetic field within the prominent inter-cluster filament recently detected in X-rays by the extended ROentgen Survey with an Imaging Telescope Array (eROSITA). This filament spans over 13 Mpc projected on the sky, connecting the galaxy clusters Abell 3667 and Abell 3651. We employed the Polarisation Sky Survey of the Universe's Magnetism (POSSUM) Rotation Measure (RM) grid to isolate the RM dispersion and median value of background polarised sources induced by the filament's magnetised plasma, and to infer the strength of this magnetic field. The filament region is sampled by 54 background polarised sources. After subtracting the foreground Galactic RM, we detected a marginal residual RM dispersion in the filament region of $6.9\pm3.6$ rad/m$^{2}$, together with a coherent residual RM signal with median $6.3\pm1.3$ rad/m$^{2}$. Assuming simplified single-scale magnetic-field models and adopting informed priors on the thermal electron density distribution derived from the X-ray analysis, we constrained the magnetic field strength to the range 0.1-3.5 $μ$G within 95$\%$ confidence, with preferred values around 0.2-0.3 $μ$G depending on the assumed magnetic-field coherence scale. However, we also found that the Galactic foreground RM in this region is highly structured on angular scales comparable to the extent of the filament itself, representing a major source of uncertainty for the RM analysis. Our results provide the first magnetic field constraints based on Faraday rotation measurements in an individual X-ray-detected inter-cluster filament, with field strengths consistent with theoretical expectations for gas in bridges and cluster outskirts. Our analysis also highlights the critical importance of accurately modelling Galactic RM foregrounds for future studies of extra-galactic magnetism with POSSUM and the SKA.
发表机构
- INAF - Istituto di Radioastronomia (IRA)（意大利国家天体物理研究所射电天文研究所）
- Universidad Complutense de Madrid（马德里康普顿斯大学）
- Minnesota Institute for Astrophysics, University of Minnesota（明尼苏达大学明尼苏达天体物理研究所）
- Centre for Radio Astronomy Techniques and Technologies (RATT), Department of Physics and Electronics, Rhodes University（罗德斯大学物理与电子学院射电天文技术与方法中心）
- South African Radio Astronomy Observatory（南非射电天文观测台）
- Dipartimento di Fisica e Astronomia, Università di Bologna（博洛尼亚大学物理与天文学系）
- Argelander-Institut für Astronomie (AIfA), Universität Bonn（波恩大学阿尔根德天文学研究所）
- Mizusawa VLBI Observatory, National Astronomical Observatory of Japan（日本国立天文台水泽VLBI观测站）
- SOKENDAI（综合研究大学院大学）
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