标题： 星系团中的磁化发电机：高红移处星系形成物理的关键作用 显示英文标题

标题： Magnetic dynamos in galaxy clusters: the crucial role of galaxy formation physics at high redshifts

摘要： 星系团中的法拉第旋转和同步辐射观测表明存在强度为$\mu\mathrm{G}$的大尺度磁场，其可能延伸至$z=4$。 星系团的非辐射宇宙学模拟显示磁场增长较为缓慢，仅在晚期才趋于饱和。 我们纳入了星系形成物理过程，并发现磁场增长显著加速。 我们在磁场演化过程中识别出三个关键阶段： 1）在高红移时，中心主导星系作为主要磁化代理，不仅磁化其附近区域，还通过引力驱动的压缩湍流产生的小尺度发电机效应以及恒星和活动星系核反馈（通过外流分布磁场），磁化大部分正在形成的原星团。 2）随着其他星系在后续时期并入正在形成的星团，这一过程继续进行，从而通过冲击压力剥离和星系风将它们之前增强的磁场传输到星系际介质（ICM）中。 3）在较低红移时，气体吸积和频繁的星团合并触发额外的小尺度发电机过程，从而防止磁场衰减，并促进磁场相干尺度的增长。 我们表明，今天在弱碰撞性ICM中观测到的磁场在碰撞尺度上始终被一致地放大。 最初，在原星团组装期间发生在碰撞性星际介质中，后来在ICM中发生在磁场相干尺度上，该尺度总是超过粒子的平均自由程，这支持使用磁流体力学来研究星团发电机效应。 我们生成了原星团的合成法拉第旋转量观测结果，强调了在宇宙黎明时研究星团形成初期磁场增长的潜力。 显示英文摘要

摘要： Observations of Faraday rotation and synchrotron emission in galaxy clusters imply large-scale magnetic fields with $\mu\mathrm{G}$ strengths possibly extending back to $z=4$. Non-radiative cosmological simulations of galaxy clusters show a comparably slow magnetic field growth that only saturates at late times. We include galaxy formation physics and find a significantly accelerated magnetic field growth. We identify three crucial stages in the magnetic field evolution. 1) At high redshift, the central dominant galaxy serves as the prime agent that magnetizes not only its immediate vicinity but also most of the forming protocluster through a combination of a small-scale dynamo induced by gravitationally driven, compressive turbulence and stellar and active galactic nuclei feedback that distribute the magnetic field via outflows. 2) This process continues as other galaxies merge into the forming cluster in subsequent epochs, thereby transporting their previously amplified magnetic field to the intracluster medium (ICM) through ram pressure stripping and galactic winds. 3) At lower redshift, gas accretion and frequent cluster mergers trigger additional small-scale dynamo processes, thereby preventing the decay of the magnetic field and fostering the increase of the magnetic coherence scale. We show that the magnetic field observed today in the weakly collisional ICM is consistently amplified on collisional scales. Initially, this occurs in the collisional interstellar medium during protocluster assembly, and later in the ICM on the magnetic coherence scale, which always exceeds the particle mean free path, supporting the use of magneto-hydrodynamics for studying the cluster dynamo. We generate synthetic Faraday rotation measure observations of protoclusters, highlighting the potential for studying magnetic field growth during the onset of cluster formation at cosmic dawn.