Global simulations of galactic dynamo driven by cosmic-rays and exploding magnetized stars
Michał Hanasz, Dominik Wóltański, Kacper Kowalik, Rafał Pawłaszek
备注：
2 pages, 2 figures, To be published in "Cosmic Magnetic Fields: From Planets, to Stars and Galaxies", K.G. Strassmeier, A.G. Kosovichev & J.E. Beckman, eds., Proc. IAU Symp. 259, CUP
We conduct global galactic--scale magnetohydrodynamical (MHD) simulations of the cosmic--ray driven dynamo. We assume that exploding stars deposit small--scale, randomly oriented, dipolar magnetic fields into the differentially rotating ISM, together with a portion of cosmic rays, accelerated in supernova shocks. Our simulations are performed with the aid of a new parallel MHD code PIERNIK. We demonstrate that dipolar magnetic fields supplied on small SN--remnant scales, can be amplified exponentially by the CR--driven dynamo to the present equipartition values, and transformed simultaneously to large galactic--scales by an inverse cascade promoted by resistive processes.
Helical randomization of magnetized Galactic and galaxy clusters plasmas: from magnetorotational disc dynamo to the Faraday rotation and synchrotron emission skies
Radiation Magneto-hydrodynamic Simulations of MRI with Zero-Net-Vertical-Flux: Necessity of Resolving the Thermal Scale For Strongly Magnetized Initial Conditions
Center for Computational Astrophysics, Flatiron Institute（计算天体物理中心，平顿研究所）；Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体物理科学系）
Can galactic magnetic fields diffuse into the voids?
Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University（斯德哥尔摩大学）；Nordita, KTH Royal Institute of Technology and Stockholm University（诺迪塔；皇家理工学院和斯德哥尔摩大学）；McWilliams Center for Cosmology & Department of Physics, Carnegie Mellon University（卡内基梅隆大学）；School of Natural Sciences and Medicine, Ilia State University（伊利亚国立大学）；Theoretical Physics Department, CERN（欧洲核子研究中心）；Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève（日内瓦大学）；Université Paris Cité, CNRS, Astroparticule et Cosmologie（巴黎西岱大学）；Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；Dipartimento di Fisica e Astronomia, Universitá di Bologna（博洛尼亚大学）
Global simulations of accretion flows onto perturbers embedded in magnetized disks -I. MRI and jet formation in ideal MHD
Charles University（查理大学）；Instituto de Astronomía, Universidad Nacional Autónoma de México（墨西哥国立自治大学天文研究所）；Niels Bohr International Academy, Niels Bohr Institute（尼尔斯·玻尔国际学院，尼尔斯·玻尔研究所）
Impact of supernova and cosmic-ray driving on the surface brightness of the galactic halo in soft X-rays
银河系的晕包含一个热等离子体，其表面亮度在软X射线中的量级为$10^{-12}$ erg cm $^{-2}$ s $^{-1}$ deg $^{-2}$。这种气体的起源尚不清楚，但到目前为止，银河系恒星形成的数值模型未能再现如此大的表面亮度。在本文中，我们分析了模拟的湍流，磁化，多相星际介质，包括热反馈的超新星爆炸以及宇宙射线反馈。我们包括一个依赖于时间的化学网络，气体和灰尘的自屏蔽，以及自引力。纯粹的热反馈本身就足以产生观测到的表面亮度，尽管它对超新星速率非常敏感。宇宙射线抑制了这种敏感性，并降低了表面亮度，因为它们驱动了较冷的外流。到目前为止，自引力的影响最大，因为它将盘中的扩散气体聚集成密集的团块和细丝，因此超新星在空隙中爆炸可以将大量的热气体喷射到晕中。这可以将表面亮度提高几个数量级。虽然我们的模拟没有达到稳定状态，但所有模拟都产生与观测相同数量级的表面亮度值，确切值敏感地取决于模拟参数。我们的结论是，恒星形成的反馈本身就足以解释热晕气体的起源，但单独的表面亮度的测量不提供有用的诊断银河系恒星形成的研究。
