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Magnetic fields are an elemental part of the interstellar medium in galaxies. However, their impact on gas dynamics and star formation in galaxies remains controversial. We use a suite of global magnetohydrodynamical simulations of isolated…

Astrophysics of Galaxies · Physics 2019-09-25 Bastian Körtgen , Robi Banerjee , Ralph E. Pudritz , Wolfram Schmidt

Magnetic fields are widely recognised as critical at many scales to galactic dynamics and structure, including multiphase pressure balance, dust processing, and star formation. Using imposed magnetic fields cannot reliably model the…

Astrophysics of Galaxies · Physics 2024-01-17 Frederick A. Gent , Mordecai-Mark Mac Low , Maarit J. Korpi-Lagg

Magnetars are highly magnetized neutron stars whose magnetic dipole ranges from $10^{14}$ to $10^{15}$ G. The MRI is considered to be a promising mechanism to amplify the magnetic field in fast-rotating protoneutron stars and form…

High Energy Astrophysical Phenomena · Physics 2021-01-27 Alexis Reboul-Salze , Jérôme Guilet , Raphaël Raynaud , Matteo Bugli

We investigate the build-up of the galactic dynamo and subsequently the origin of a magnetic driven outflow. We use a setup of an isolated disc galaxy with a realistic circum-galactic medium (CGM). We find good agreement of the galactic…

Astrophysics of Galaxies · Physics 2020-04-01 Ulrich P. Steinwandel , Klaus Dolag , Harald Lesch , Benjamin P. Moster , Andreas Burkert , Almudena Prieto

The interstellar medium (ISM) is permeated by magnetic fields that affect gas dynamics and star formation. These fields correlate with supernova (SN)-driven turbulence, but whether the scaling is universal across galaxy properties, ISM…

Astrophysics of Galaxies · Physics 2026-03-31 Davide Belfiori , Sergio Martin-Alvarez , Enrique Lopez-Rodriguez , Rosita Paladino

We present a scenario for efficient magnetization of very young galaxies about 0.5 Gigayears after the Big-Bang by a cosmic ray-driven dynamo. These objects experience a phase of strong star formation during this first $10^9$ years. We…

Astrophysics · Physics 2009-11-07 H. Lesch , M. Hanasz

Magnetic fields are known to be dynamically important in the interstellar medium of our own Galaxy, and they are ubiquitously observed in diffuse gas in the halos of galaxies and galaxy clusters. Yet, magnetic fields have typically been…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-05 R. Pakmor , V. Springel

Feedback processes in galaxies dictate their structure and evolution. Baryons can be cycled through stars, which inject energy into the interstellar medium (ISM) in supernova explosions, fueling multiphase galactic winds. Cosmic rays (CRs)…

Astrophysics of Galaxies · Physics 2025-06-16 Brandon Sike , Timon Thomas , Mateusz Ruszkowski , Christoph Pfrommer , Matthias Weber

Dynamically, cosmic rays with energies above about one GeV/nucleon may be important agents of galaxy evolution. Their pressures compare with the thermal and magnetic ones impacting galactic gas accretion, fountains and galactic outflows,…

High Energy Astrophysical Phenomena · Physics 2022-05-18 A. Nuñez-Castiñeyra , I. A. Grenier , F. Bournaud , Y. Dubois , F. R. Kamal Youssef , P. Hennebelle

Magnetic fields are an important ingredient of the interstellar medium (ISM). Besides their importance for star formation, they govern the transport of cosmic rays, relevant to the launch and regulation of galactic outflows and winds, which…

The ordered magnetic field observed via polarized synchrotron emission in nearby disc galaxies can be explained by a mean-field dynamo operating in the diffuse interstellar medium (ISM). Additionally, vertical-flux initial conditions are…

Astrophysics of Galaxies · Physics 2016-01-06 A. Bendre , O. Gressel , D. Elstner

Recent years have seen many arguments for cosmic rays (CRs) as an important influence on galactic and circumgalactic (CGM) physics, star and galaxy formation. We present a pedagogical overview of state-of-the-art modeling of…

Astrophysics of Galaxies · Physics 2026-05-11 Philip F. Hopkins

We use global MHD galaxy simulations to investigate the effects of spiral arms on the evolution of magnetic fields and star formation within a self-regulated interstellar medium (ISM). The same galaxy is simulated twice: once with…

Astrophysics of Galaxies · Physics 2025-06-23 Hector Robinson , James Wadsley , J. A. Sellwood , Ralph E. Pudritz

We investigate the dynamical interaction between cosmic rays (CRs) and the multiphase interstellar medium (ISM) using numerical magnetohydrodynamic (MHD) simulations with a two-moment CR solver and TIGRESS simulations of star-forming…

Astrophysics of Galaxies · Physics 2024-01-10 Lucia Armillotta , Eve C. Ostriker , Chang-Goo Kim , Yan-Fei Jiang

Observationally, magnetic fields reach equipartition with thermal energy and cosmic rays in the interstellar medium of disk galaxies such as the Milky Way. However, thus far cosmological simulations of the formation and evolution of…

Astrophysics of Galaxies · Physics 2015-06-18 R. Pakmor , F. Marinacci , V. Springel

Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. $10^{15}$ eV. A stronger…

High Energy Astrophysical Phenomena · Physics 2016-03-16 Maria Victoria del Valle , Alexandre Lazarian , Reinaldo Santos-Lima

Several lines of evidence suggest that protogalactic and galactic environments manage to grow magnetic field very rapidly. This makes the theoretical problem of achieving rapid growth of magnetic fields in such environments difficult.…

Astrophysics · Physics 2009-11-10 D. S. Balsara , J. S. Kim , M. M. Mac Low , G. Mathews

We explore the effect of magnetic fields on the vertical distribution and multiphase structure of the supernova-driven interstellar medium (ISM) in simulations that admit dynamo action. As the magnetic field is amplified to become…

Astrophysics of Galaxies · Physics 2019-09-26 C. C. Evirgen , F. A. Gent , A. Shukurov , A. Fletcher , P. J. Bushby

We study the effects of cosmic rays (CRs) on outflows from star-forming galaxies in the circum and inter-galactic medium (CGM/IGM), in high-resolution, fully-cosmological FIRE-2 simulations (accounting for mechanical and radiative stellar…

The role of magnetic fields in the multi-phase interstellar medium (ISM) is explored using magnetohydrodynamic (MHD) simulations that include energy injection by supernova (SN) explosions and allow for dynamo action. Apart from providing…

Astrophysics of Galaxies · Physics 2018-10-03 A. Shukurov , C. C. Evirgen , A. Fletcher , P. J. Bushby , F. A. Gent