Simulating Magnetic Fields in the Antennae Galaxies

Kotarba, Hanna; Karl, Simon J.; Naab, Thorsten; Johansson, Peter H.; Dolag, K.; Lesch, H.; Stasyszyn, Federico

doi:10.1088/0004-637x/716/2/1438

Cited by 46 publications

(99 citation statements)

References 98 publications

(125 reference statements)

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“…We have performed simulations of three colliding galaxies to proof the saturation and equipartition phenomena seen in Kotarba et al, 2010a on the basis of a more general setup (Kotarba et al, 2010b). In these simulations, the magnetic field saturates at a value of about 1 G -which is again consistent with observations -, independent of the initial value.…”

Section: Simulationssupporting

confidence: 69%

“…A perfect example of the strong coupling of gas and magnetic fields is the interacting system NGC4038/4039 (the "Antennae galaxies"). We have simulated this system including magnetic fields for the first time (Kotarba et al, 2010a). The simulations demonstrated that even an initial magnetic field as small as 10 −9 G is efficiently amplified during the interaction of two equal-mass spiral galaxies.…”

Section: Simulationsmentioning

confidence: 99%

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The fate of magnetic fields in colliding galaxies

et al. 2010

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Abstract. The evolution and amplification of large-scale magnetic fields in galaxies is investigated by means of high resolution simulations of interacting galaxies. The goal of our project is to consider in detail the role of gravitational interaction of galaxies for the fate of magnetic fields. Since the tidal interaction up to galaxy merging is a basic ingredient of cold-dark matter (CDM) structure formation models we think that our simulations will give important clues for the interplay of galactic dynamics and magnetic fields.

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Section: Simulationssupporting

confidence: 69%

Section: Simulationsmentioning

confidence: 99%

The fate of magnetic fields in colliding galaxies

et al. 2010

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“…The average total magnetic field is stronger than that in normal spirals, but the mean degree of polarization is unusually low, implying that the fields are tangled. The Antennae galaxies have been modelled by Kotarba et al (2010), who could reproduce the main features observed in the radio image.…”

Section: Beyond Spirals: Interacting Galaxiesmentioning

confidence: 99%

Magnetic fields in spiral galaxies

Beck¹

2015

Astron Astrophys Rev

368

269

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Radio synchrotron emission, its polarization and Faraday rotation of the polarization angle are powerful tools to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30 μG) and in central starburst regions (50-100 μG). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15 μG) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the intergalactic medium.-Faraday rotation measures of the diffuse polarized radio emission from galaxy disks reveal large-scale spiral patterns that can be described by the superposition of azimuthal modes; these are signatures of regular fields generated by mean-field dynamos. "Magnetic arms" between gaseous spiral arms may also be products of dynamo action, but need a stable spiral pattern to develop. Helically twisted field loops winding around spiral arms were found in two galaxies so far. Large-scale field reversals, like the one found in the Milky Way, could not yet be detected in external galaxies. In radio halos around edgeon galaxies, ordered magnetic fields with X-shaped patterns are observed. The origin and evolution of cosmic magnetic fields, in particular their first occurrence in young

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“…Since gas and magnetic fields are tightly coupled, the magnetic fields trace the gas motion and will be strengthened by shocks and gas inflow. A perfect example for the strong coupling of gas and magnetic fields is the interacting system NGC 4038/4039 (the ‘Antennae galaxies’) which has been recently simulated (Karl et al 2010) by Kotarba et al (2010) including magnetic fields. It was shown that even an initial magnetic field as small as 10 −9 G grows significantly during the interaction of two equal‐mass spiral galaxies.…”

Section: Introductionmentioning

confidence: 99%

Galactic ménage à trois: simulating magnetic fields in colliding galaxies

Kotarba

Lesch²,

Dolag

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We present high‐resolution simulations of a multiple merger of three disc galaxies, including the evolution of magnetic fields, performed with the N‐body/smoothed particle hydrodynamics (SPH) code Gadget. For the first time, we embed the galaxies in a magnetized, low‐density medium, thus modelling an ambient intergalactic medium (IGM). The simulations include radiative cooling and a model for star formation and supernova feedback. Magnetohydrodynamics is followed using the SPH method. The progenitor discs have initial magnetic seed fields in the range 10−9–10−6 G and the IGM has initial fields of 10−12–10−9 G. The simulations are compared to a run excluding magnetic fields. We show that the propagation of interaction‐driven shocks depends significantly on the initial magnetic field strength. The shocks propagate faster in simulations with stronger initial field, suggesting that the shocks are supported by magnetic pressure. The Mach numbers of the shocks range from approximately M= 1.5 for the non‐magnetized case up to M= 6 for the highest initial magnetization, resulting in higher temperatures of the shock‐heated IGM gas. The magnetic field in the system saturates rapidly after the mergers at ∼10−6 G within the galaxies and ∼10−8 G in the IGM independent of the initial value. These field strengths agree with observed values and correspond to the equipartition value of the magnetic pressure with the turbulent pressure in the system. We also present synthetic radio and polarization maps for different phases of the evolution, showing that shocks driven by the interaction produce a high amount of polarized emission. These idealized simulations indicate that magnetic fields play an important role for the hydrodynamics of the IGM during galactic interactions. We also show that even weak seed fields are efficiently strengthened during multiple galactic mergers. This interaction‐driven amplification might have been a key process for the magnetization of the Universe.

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Simulating Magnetic Fields in the Antennae Galaxies

Cited by 46 publications

References 98 publications

The fate of magnetic fields in colliding galaxies

The fate of magnetic fields in colliding galaxies

Magnetic fields in spiral galaxies

Galactic ménage à trois: simulating magnetic fields in colliding galaxies

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