Evolution of hydromagnetic turbulence from the electroweak phase transition

Brandenburg, Axel; Kahniashvili, Tina; Mandal, Sayan; Pol, Alberto Roper; Tevzadze, Alexander G.; Vachaspati, Tanmay

doi:10.1103/physrevd.96.123528

Cited by 104 publications

(101 citation statements)

References 64 publications

(121 reference statements)

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“…where the tensorsη ij (k z , ω) andβ ijz (k z , ω) are simply related as η xx =β xyz ,η xy = −β xxz ,η yx =β yyz , andη yy = −β yxz (see Brandenburg & Sokoloff 2002). Assuming steady-state (and/or homogeneous) conditions, the RHS of equation (12) is typically accumulated in time (and/or space) to obtain a sufficient statistical basis, but the method can in principle even deliver time-varying α and η.…”

Section: The Spectral Test-field Methodsmentioning

confidence: 99%

“…How does this non-locality affect the evolution of the derived dynamo? To answer this question comprehensively, detailed mean-field calculations will be required (see, e.g., Brandenburg & Sokoloff 2002, who have demonstrated a change in the propagation of the dynamo wave for the case of MRI turbulence). In the following, we present a brief assessment in terms of dynamo numbers.…”

Section: Scale Dependencementioning

confidence: 99%

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On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence

Gressel

Elstner

2020

Monthly Notices of the Royal Astronomical Society

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The interstellar medium of the Milky Way and nearby disk galaxies harbours large-scale coherent magnetic fields of Microgauss strength, that can be explained via the action of a mean-field dynamo. As in our previous work, we aim to quantify dynamo effects that are selfconsistently emerging in realistic direct magnetohydrodynamic simulations, but we generalise our approach to the case of a non-local (non-instantaneous) closure relation, described by a convolution integral in space (time). To this end, we leverage our comprehensive simulation framework for the supernova-regulated turbulent multi-phase interstellar medium. By introducing spatially (temporally) modulated mean fields, we extend the previously used test-field method to the spectral realm -providing the Fourier representation of the convolution kernels. The resulting spectra of the dynamo mean-field coefficients that we obtain broadly match expectations and allow to rigorously constrain the degree of scale separation in the Galactic dynamo. A surprising result is found for the diamagnetic pumping term, which increases in amplitude when going to smaller scales. Our results amount to the most comprehensive description of dynamo mean-field effects in the Galactic context to date. Surveying the relevant parameter space and quenching behaviour, this will ultimately enable the development of assumption-free sub-grid prescriptions for otherwise unresolved global galaxy simulations.

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Section: The Spectral Test-field Methodsmentioning

confidence: 99%

Section: Scale Dependencementioning

confidence: 99%

On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence

Gressel

Elstner

2020

Monthly Notices of the Royal Astronomical Society

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“…Here n B and n λ are positive constants, which are determined by the helicity of the magnetic fields and properties of the turbulence [55,56]. Supposing that (i) the equilibration of the magnetic fields and velocity fields 3 and (ii) the coherence length is determined by the eddy scale of the turbulence, λ c ∼ vt ∝ B c t, we have n B ¼ 1 − n λ , which is also seen in the MHD simulations.…”

Section: B Second Stage: V ≠mentioning

confidence: 68%

“…At that stage, the standard MHD studies (without dark magnetic fields) have shown that the magnetic fields evolve according to a scaling law that depends on whether there is an inverse cascade [48][49][50][51], direct cascade [41,48,49,52], or inverse transfer [53][54][55][56]. In any case, as a first approximation, the magnetic fields are described by the comoving field strength B…”

Section: B Second Stage: V ≠mentioning

confidence: 99%

Magnetic field transfer from a hidden sector

Kamada¹,

Tsai²,

Vachaspati³

2018

Phys. Rev. D

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Primordial magnetic fields in the dark sector can be transferred to magnetic fields in the visible sector due to a gauge kinetic mixing term. We show that the transfer occurs when the evolution of magnetic fields is dominated by dissipation due to finite electric conductivity, and does not occur at later times if the magnetic fields evolve according to magnetohydrodynamics scaling laws. The efficiency of the transfer is suppressed by not only the gauge kinetic mixing coupling but also the ratio between the large electric conductivity and the typical momentum of the magnetic fields. We find that the transfer gives nonzero visible magnetic fields today. However, without possible dynamo amplifications, the field transfer is not efficient enough to obtain the intergalactic magnetic fields suggested by the gamma-ray observations, although there are plenty of possibilities for efficient dark magnetogenesis, which are experimentally unconstrained.

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“…Studies of the MHD equations show that a cosmological magnetic field with helicity evolves so that at late times [17][18][19][20] …”

mentioning

confidence: 99%

Fundamental implications of intergalactic magnetic field observations

Vachaspati

2017

Phys. Rev. D

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Helical intergalactic magnetic fields at the ∼ 10 −14 G level on ∼ 10 Mpc length scales are indicated by current gamma ray observations. The existence of magnetic fields in cosmic voids and their non-trivial helicity suggest that they must have originated in the early universe and thus have implications for the fundamental interactions. I combine present knowledge of the observational constraints and the dynamics of cosmological magnetic fields to derive characteristics that would need to be explained by the magnetic field generation mechanism. The importance of CP violation and a possible crucial role for chiral effects in the early universe are pointed out.

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Evolution of hydromagnetic turbulence from the electroweak phase transition

Cited by 104 publications

References 64 publications

On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence

On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence

Magnetic field transfer from a hidden sector

Fundamental implications of intergalactic magnetic field observations

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