Simulations of magnetic fields in isolated disc galaxies

By Rüdiger Pakmor, Volker Springel. 2012

208 citations recorded by the source corpus.

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 neglected in studies of the formation of galaxies, leaving their global influence on galaxy formation largely unclear. We extend our MHD implementation in the moving-mesh code Arepo to cosmological problems which include radiative cooling and the formation of stars. In particular, we replace our previously employed divergence cleaning approach with a Powell 8-wave scheme, which turns out to be significantly more stable, even in very dynamic environments. We verify the improved accuracy through simulations of the MRI in accretion disks, that reproduce its correct linear growth rate. Using this new MHD code, we simulate the formation of isolated disk galaxies similar to the Milky Way using idealized initial conditions with and without magnetic fields. We find that the magnetic field is quickly amplified in the initial starburst and the differential rotation of the forming disk until it eventually saturates when it becomes comparable to the thermal pressure. The additional pressure component leads to a lower star formation rate at late times compared to simulations without magnetic fields, and induces changes in the spiral arm structures of the gas disk. In addition, we observe highly magnetized fountain-like outflows from the disk. These results are robust with numerical resolution and are largely independent of the initial magnetic seed field assumed in the initial conditions, as the amplification process is rapid and self-regulated. Our findings suggest an important influence of magnetic fields on galaxy formation and evolution, cautioning against their neglect in theoretical models of structure formation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/8de9b502de3ce9c3b76bcb93bf4ef2331d08b61c

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In Astronomy and Astrophysics

1. L. Hernquist
2. Volker Springel
3. P. Hopkins
4. M. Vogelsberger
5. T. Naab
6. Shy Genel
7. P. Torrey
8. A. Dekel

Citations in the corpus

• First results from the TNG50 simulation: galactic outflows driven by supernovae and black hole feedback (2019, methodology): “TNG uses the AREPO code (Springel 2010) which solves for the coupled evolution under (self-)gravity and ideal, continuum 1 http://www.tng-project.org MHD (Pakmor et al. 2011; Pakmor & Springel 2013).”
• The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time (2016, methodology): “We have now implemented magnetic fields into the galaxy formation model (see Pakmor & Springel 2013; Pakmor, Marinacci & Springel 2014), which, until recently, was not possible owing to the well-known difficulties in controlling amplification and divergence errors.”
• First results from the IllustrisTNG simulations: matter and galaxy clustering (2017, background): “…model for the low accretion state (Weinberger et al. 2017b), an improved parametrization of galactic winds (Pillepich et al. 2018), and the inclusion of magnetic fields based on ideal magneto-hydrodynamics (Pakmor, Bauer & Springel 2011; Pakmor & Springel 2013; Pakmor, Marinacci & Springel 2014).”
• Vertical disc heating in Milky Way-sized galaxies in a cosmological context (2015, methodology): “Magnetic fields are implemented following the method described in Pakmor & Springel (2013).”
• Supermassive black holes and their feedback effects in the IllustrisTNG simulation (2017, methodology): “The divergence constraint of the magnetic field is taken care of by an 8-wave Powell-cleaning scheme (Pakmor & Springel 2013).”
• A sub-parsec resolution simulation of the Milky Way: global structure of the interstellar medium and properties of molecular clouds (2013, background): “We also note that including magnetic fields could modify the morphology of spiral arms (Pakmor & Springel 2013) and their collapse into clouds via magneto-Jeans instabilities (Kim et al. 2002).”
• Simulating galaxy formation with black hole driven thermal and kinetic feedback (2016, methodology): “• Ideal magnetohydrodynamics is included based on a Powell cleaning scheme (Pakmor et al. 2011; Pakmor & Springel 2013).”
• Simulating galaxy formation with the IllustrisTNG model (2017, methodology): “This follows Pakmor, Marinacci & Springel (2014) who found that, compared to not removing the B-field (as done instead in Pakmor & Springel 2013), this choice gives somewhat smaller magnetic field strengths in galaxies, by at most a few tens of percent.”
• First results from the IllustrisTNG simulations: the stellar mass content of groups and clusters of galaxies (2017, methodology): “The divergence constraint of the magnetic field is taken care of by an 8-wave Powell cleaning scheme described in Pakmor & Springel (2013).”
• First results from the IllustrisTNG simulations: the galaxy colour bimodality (2017, methodology): “…the AREPO code (Springel 2010) to solve the coupled equations of self-gravity and ideal, continuum magneto-hydrodynamics (MHD; Pakmor et al. 2011; Pakmor & Springel 2013), the former computed with the TreePM approach and the latter employing a Godunov/finite-volume method with a spatial…”
• First results from the IllustrisTNG simulations: radio haloes and magnetic fields (2017, methodology): “The principal differences with respect to Illustris are: a new radio mode AGN feedback model (Weinberger et al. 2017), a revised SN wind model and refinements in the chemical evolution (Pillepich et al. 2017), and the addition of ideal MHD (Pakmor et al. 2011; Pakmor & Springel 2013).”
• Theoretical Challenges in Galaxy Formation (2016, background): “…has to be considered and significant progress has been made recently (Dolag, Bykov & Diaferio 2008; Dolag et al. 2005; Dolag & Stasyszyn 2009; Dubois & Teyssier 2010; Kotarba et al. 2010, 2009; Pakmor, Marinacci & Springel 2014; Pakmor et al. 2016; Pakmor & Springel 2013; Rieder & Teyssier 2016).”