A small-scale dynamo in feedback-dominated galaxies as the origin of cosmic magnetic fields - I. The kinematic phase

Michael Rieder; Romain Teyssier

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A small-scale dynamo in feedback-dominated galaxies as the origin of cosmic magnetic fields - I. The kinematic phase

Michael Rieder, Romain Teyssier

Astrophysics of Galaxies · Submitted 2 Jun 2015

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim Our findings suggest that weak initial seed fields were first amplified by a small-scale dynamo during a violent, feedback-dominated early phase in the galaxy formation history, followed by a more quiescent evolution, where the fields have slowly decayed or were maintained via large-scale dynamo action.

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arXiv ID1506.00849 (version 2)

Pith ID5A5PMGJF, Pith's permanent record of this paper and its review

CitationMichael Rieder, Romain Teyssier. "A small-scale dynamo in feedback-dominated galaxies as the origin of cosmic magnetic fields - I. The kinematic phase." arXiv:1506.00849 (2015). https://pith.science/paper/5A5PMGJF

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The compiled record

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What the abstract itself states, as probabilities: claims first 0.05 · states limitation 0.18 · human participants 0.01 · controlled comparison 0.21 · randomized assignment 0.01 · states quantitative result 0.64 · compares with prior results 0.33 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; show every role.

The origin and evolution of magnetic fields in the Universe is still an open question. Their observations in galaxies suggest strong magnetic fields already at high redshift as well as at present time. However, neither primordial magnetic fields nor battery processes can account for such high field strengths, which implies the presence of a dynamo process with rapid growth rates in high-redshift galaxies and subsequent maintenance against decay. We investigate the particular role played by feedback mechanisms in creating strong fluid turbulence, allowing for a magnetic dynamo to emerge. Performing magnetohydrodynamic simulations of isolated cooling gas halos, we compare the magnetic field evolution for various initial field topologies and various stellar feedback mechanisms. We find that feedback can indeed drive strong gas turbulence and dynamo action. We see typical properties of Kolmogorov turbulence with a $k^{-5/3}$ kinetic energy spectrum, as well as a small-scale dynamo, with a $k^{3/2}$ magnetic energy spectrum predicted by Kazantsev dynamo theory. We also investigate simulations with a final quiescent phase. As turbulence decreases, the galactic fountain settles into a thin, rotationally supported disk. The magnetic field develops a large-scale, well-ordered structure with even symmetry, which is in good agreement with magnetic field observations of nearby spirals. Our findings suggest that weak initial seed fields were first amplified by a small-scale dynamo during a violent, feedback-dominated early phase in the galaxy formation history, followed by a more quiescent evolution, where the fields have slowly decayed or were maintained via large-scale dynamo action.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	The origin and evolution of magnetic fields in the Universe is still an open question.	background 0.90	0.03	0.01	asserted 0.99
s1	Their observations in galaxies suggest strong magnetic fields already at high redshift as well as at present time.	background 1.00	0.10	0.02	hedged possibility 0.67
s2	However, neither primordial magnetic fields nor battery processes can account for such high field strengths, which implies the presence of a dynamo process with rapid growth rates in high-redshift galaxies and subsequent maintenance against decay.	gap 0.67	0.09	0.06	asserted 0.88
s3	We investigate the particular role played by feedback mechanisms in creating strong fluid turbulence, allowing for a magnetic dynamo to emerge.	contribution 0.97	0.34	0.04	unclear 0.60
s4	Performing magnetohydrodynamic simulations of isolated cooling gas halos, we compare the magnetic field evolution for various initial field topologies and various stellar feedback mechanisms.	method 0.97	0.95	0.02	asserted 0.75
s5	We find that feedback can indeed drive strong gas turbulence and dynamo action.	result 1.00	0.97	0.26	asserted 0.95
s6	We see typical properties of Kolmogorov turbulence with a $k^{-5/3}$ kinetic energy spectrum, as well as a small-scale dynamo, with a $k^{3/2}$ magnetic energy spectrum predicted by Kazantsev dynamo theory.	result 1.00	0.92	0.10	asserted 1.00
s7	We also investigate simulations with a final quiescent phase.	contribution 0.51	0.91	0.02	asserted 0.77
s8	As turbulence decreases, the galactic fountain settles into a thin, rotationally supported disk.	result 1.00	0.84	0.03	asserted 1.00
s9	The magnetic field develops a large-scale, well-ordered structure with even symmetry, which is in good agreement with magnetic field observations of nearby spirals.	result 0.98	0.90	0.09	asserted 0.92
s10	Our findings suggest that weak initial seed fields were first amplified by a small-scale dynamo during a violent, feedback-dominated early phase in the galaxy formation history, followed by a more quiescent evolution, where the fields have slowly decayed or were maintained via large-scale dynamo action.	interpretation 0.99	0.77	0.94	hedged possibility 1.00

What kind of paper the classifier reports this is: simulation study 1.00 · evidence from simulation or computation 1.00.

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sources read

arXiv listing abstract v2

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

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S sections
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C citations
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Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper

Original abstract

The origin and evolution of magnetic fields in the Universe is still an open question. Their observations in galaxies suggest strong magnetic fields already at high redshift as well as at present time. However, neither primordial magnetic fields nor battery processes can account for such high field strengths, which implies the presence of a dynamo process with rapid growth rates in high-redshift galaxies and subsequent maintenance against decay. We investigate the particular role played by feedback mechanisms in creating strong fluid turbulence, allowing for a magnetic dynamo to emerge. Performing magnetohydrodynamic simulations of isolated cooling gas halos, we compare the magnetic field evolution for various initial field topologies and various stellar feedback mechanisms. We find that feedback can indeed drive strong gas turbulence and dynamo action. We see typical properties of Kolmogorov turbulence with a $k^{-5/3}$ kinetic energy spectrum, as well as a small-scale dynamo, with a $k^{3/2}$ magnetic energy spectrum predicted by Kazantsev dynamo theory. We also investigate simulations with a final quiescent phase. As turbulence decreases, the galactic fountain settles into a thin, rotationally supported disk. The magnetic field develops a large-scale, well-ordered structure with even symmetry, which is in good agreement with magnetic field observations of nearby spirals. Our findings suggest that weak initial seed fields were first amplified by a small-scale dynamo during a violent, feedback-dominated early phase in the galaxy formation history, followed by a more quiescent evolution, where the fields have slowly decayed or were maintained via large-scale dynamo action.

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48 later papers cite it

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2 papers by the same authors are listed below: 2 built on it.

Builds on it 2 of 3 papers with this label · 2 by the same authors

By the same authors

Followed up on this paper's work, using again the isolated cooling halo setup with strong stellar feedback to investigate magnetic field amplification through the small-scale dynamo.

A small-scale dynamo in feedback-dominated galaxies - II. The saturation phase and the final magnetic configuration (2017) (same authors) · 0.98 · paraphrased: the licence does not allow quoting
Extended this paper's study of magnetic field amplification in isolated spiral galaxies by accounting for galaxy mergers and gas accretion.

A three-phase amplification of the cosmic magnetic field in galaxies (2018) (same authors) · 1.00 · paraphrased: the licence does not allow quoting

How the literature uses it

6 arXiv papers cite this in 9 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 8 sentences without a confident label

Cites it as background 1 paper

Isolated galactic simulations have investigated magnetic field amplification and saturation from weak seed fields [ref] , their effects on star formation rates [ref] , and their role in launching outflows [ref] .

Magnetic destabilisation in disc galaxies: Filament/feather formation · Introduction · 0.90

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