On the amplification of magnetic fields in cosmic filaments and galaxy clusters
F. Vazza, M. Brüggen, C. Gheller, P. Wang
备注：
MNRAS accepted, in press. 18 pages, 18 Figures. New version to match with the one published in MNRAS. Updated publication list and footnote added to the title as obituary notice
The amplification of primordial magnetic fields via a small-scale turbulent dynamo during structure formation might be able to explain the observed magnetic fields in galaxy clusters. The magnetisation of more tenuous large-scale structures such as cosmic filaments is more uncertain, as it is challenging for numerical simulations to achieve the required dynamical range. In this work, we present magneto-hydrodynamical cosmological simulations on large uniform grids to study the amplification of primordial seed fields in the intracluster medium (ICM) and in the warm-hot-intergalactic medium (WHIM). In the ICM, we confirm that turbulence caused by structure formation can produce a significant dynamo amplification, even if the amplification is smaller than what is reported in other papers. In the WHIM inside filaments, we do not observe significant dynamo amplification, even though we achieve Reynolds numbers of $R_{\rm e} \sim 200-300$. The maximal amplification for large filaments is of the order of $\sim 100$ for the magnetic energy, corresponding to a typical field of a few $\sim \rm nG$ starting from a primordial weak field of $10^{-10}$ G (comoving). In order to start a small-scale dynamo, we found that a minimum of $\sim 10^2$ resolution elements across the virial radius of galaxy clusters was necessary. In filaments we could not find a minimum resolution to set off a dynamo. This stems from the inefficiency of supersonic motions in the WHIM in triggering solenoidal modes and small-scale twisting of magnetic field structures. Magnetic fields this small will make it hard to detect filaments in radio observations.
Velocity fields and turbulence from cosmic filaments to galaxy clusters
Université Paris-Saclay（巴黎萨克雷大学）；CNRS（法国国家科学研究中心）；Institut d’Astrophysique Spatiale（天体物理研究所）；The Open University of Israel（以色列开放大学）；Kapteyn Astronomical Institute（卡普坦天文研究所）；University of Groningen（格罗宁根大学）；Université de Lille（里尔大学）；Centrale Lille（里尔中央理工学院）；CRIStAL（晶体与材料研究中心）
Cosmic filaments confirm unexplained CMB temperature decrements in two independent redshift ranges
Facultad de Matemática, Astronomía, Física y Computación (FAMAF), UNC（数学、天文学、物理与计算学院（FAMAF），科尔多瓦大学）；UNC, Córdoba, Argentina（科尔多瓦大学，阿根廷科尔多瓦）；Observatorio Astronómico de Córdoba (OAC), UNC, Córdoba, Argentina（科尔多瓦天文台（OAC），科尔多瓦大学，阿根廷科尔多瓦）；Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway（奥斯陆大学理论天体物理研究所）；Instituto de Astronomía Teórica y Experimental (IATE), CONICET-UNC, Córdoba, Argentina（理论与实验天文学研究所（IATE），CONICET-科尔多瓦大学，阿根廷科尔多瓦）
Filament-Arm Node Systems (FANS): A new probe of the winding and chirality of the cosmic web
Center for Cosmology and Computational Astrophysics, Institute for Advanced Study in Physics, Zhejiang University（浙江大学高等物理研究院宇宙学与计算天体物理学中心）；Institute of Astronomy, School of Physics, Zhejiang University（浙江大学物理学院天文学研究所）
Detection of HI filament: Pair Stacking vs. Filament Stacking
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文学与空间科学学院）
Crawling the Cosmic Network: Identifying and Quantifying Filamentary Structure
We present the Smoothed Hessian Major Axis Filament Finder (SHMAFF), an algorithm that uses the eigenvectors of the Hessian matrix of the smoothed galaxy distribution to identify individual filamentary structures. Filaments are traced along the Hessian eigenvector corresponding to the largest eigenvalue, and are stopped when the axis orientation changes more rapidly than a preset threshold. In both N-body simulations and the Sloan Digital Sky Survey (SDSS) main galaxy redshift survey data, the resulting filament length distributions are approximately exponential. In the SDSS galaxy distributio…
First Observational Evidence for Split Infall Flow of Cosmic Filaments into Clusters
University of Chinese Academy of Sciences（中国科学院大学）；Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院天文学系）；Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交通大学李政道研究所）
Alignments of galaxies within cosmic filaments from SDSS DR7
利用从斯隆数字巡天数据发布7（SDSS DR 7）中选取的星系群样本，我们在宇宙网的背景下研究了星系取向与其周围大尺度结构之间的对齐。后者是量化使用大规模的潮汐场，重建的数据使用星系群以上的一定质量阈值。我们发现，在长丝星系的主轴往往是优先与长丝的方向对齐，而在片星系的主轴优先对齐平行的平面片。这种对齐信号的强度是最强的红色，中央星系，并在良好的协议与暗物质晕在N体模拟。这表明，红色的中央星系与它们的宿主晕很好地对齐，与以前基于卫星星系空间分布的研究定量一致。有一个光度和质量的依赖性，更明亮，更大质量的星系在丝和片有更强的对齐信号。我们还发现，星系的取向与潮汐张量的最小本征值相关联的本征向量对齐。这些观测结果表明，星系形成受到大尺度环境的影响，并强烈表明星系在宇宙网中的片和丝尺度上相互排列。
我们分析了定义宇宙网络的不同形态的结构和连通性。利用我们的多尺度形态滤波器（MMF），我们将宇宙学$Λ$ CDM N体计算机模拟的物质分布分解为团簇、细丝和壁。的MMF是理想的适合于解决两个各向异性的形态特征的丝和片，以及多尺度性质的分层演化的宇宙物质分布。我们的研究结果可以总结如下：i）。虽然所有形态都占据了大致明确的密度范围，但考虑到它们的重叠，仅凭这一点不足以区分它们。仅根据密度定义的环境未能包含每个形态的内在动力学。这在晕之间的线性和非线性相互作用中起着重要作用。（ii）─宇宙中的大部分质量都集中在细丝中，紧接着是星团。就体积而言，团簇只占很小的一部分，细丝不超过9%。墙壁在质量和体积方面相对不明显。（iii）-平均而言，大质量的星系团比低质量的星系团连接更多的细丝。具有$M \sim 10^{14}$ M $_{\odot}$ h $^{-1}$的簇平均具有两个连接丝，而具有$M \geq 10^{15}$ M $_{\odot}$ h $^{-1}$的簇平均具有五个连接丝。（iv）-密度分布表明，长丝的典型宽度为2 $\Mpch$。墙的边界不太清晰，宽度在5-8 Mpc h $^{-1}$之间。在其内部，长丝具有幂律密度分布，斜率为$γ\approx -1$，对应于等温密度分布。
Constraining the Baryon Content of Cosmic Filaments Using Localized Fast Radio Bursts and DESI Imaging Data
School of Physics and Astronomy, Sun Yat-Sen University（中山大学物理学院）；CSST Science Center for the Guangdong-Hong Kong-Macau Greater Bay Area（粤港澳大湾区宇宙线科学中心）
The WEFT project: I. The emergence of turbulence in a cosmic filament
Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；Astrophysics Research Center of the Open University (ARCO), The Open University of Israel（以色列开放大学天体物理研究中心）
Tracing Missing Baryons in the Cosmic Filaments with tSZ and CMB-Lensing Stacking
School of Physics and Astronomy, Sun Yat-sen University（中山大学物理学院）；CSST Science Center for the Guangdong-Hong kong-Macau Greater Bay Area, SYSU（中山大学粤港澳大湾区深空探测科学中心）
