Probing large-scale magnetism with the cosmic microwave background

Giovannini, Massimo

doi:10.1088/1361-6382/aab17d

Cited by 25 publications

(20 citation statements)

References 375 publications

(891 reference statements)

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“…It is now trivial to check that, in the limit eB → 0, the above equation exactly boils down to the 1 2 times pure vacuum contribution given in Eq. (10). Thus extracting the pure vacuum contribution from the above equation we get, In this appendix we will calculate the quantities N µν π,nl (q , k ) = d 2 k ⊥ (2π) 2 N µν π,nl (q , q ⊥ = 0, k) (E1) N µν p,nl (q , k ) = d 2 k ⊥ (2π) 2 N µν p,nl (q , q ⊥ = 0, k) .…”

Section: Appendix D: Calculation Of Eb-dependent Vacuum Contribution mentioning

confidence: 99%

General structure of the neutral ρ meson self-energy and its spectral properties in a hot and dense magnetized medium

et al. 2019

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The one loop self energy of the neutral ρ meson is obtained for the effective ρππ and ρN N interaction at finite temperature and density in the presence of a constant background magnetic field of arbitrary strength. In our approach, the eB-dependent vacuum part of the self energy is extracted by means of dimensional regularization where the ultraviolet divergences corresponding to the pure vacuum self energy manifest as the pole singularities of gamma as well as Hurwitz zeta functions. This improved regularization procedure consistently reproduces the expected results in the vanishing magnetic field limit and can be used quite generally in other self energy calculations dealing with arbitrary magnetic field strength. In presence of the external magnetic field, the general Lorentz structure for the in-medium vector boson self energy is derived which can also be implemented in case of the gauge bosons such as photons and gluons. It has been shown that with vanishing perpendicular momentum of the external particle, essentially two form factors are sufficient to describe the self energy completely. Consequently, two distinct modes are observed in the study of the effective mass, dispersion relations and the spectral function of ρ 0 where one of the modes possesses two fold degeneracy. For large baryonic chemical potential, it is observed that the critical magnetic field required to block the ρ 0 → π + π − decay channel increases significantly with temperature. However, in case of smaller values reaching down to vanishing chemical potential, the critical field follows the opposite trend.

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Section: Appendix D: Calculation Of Eb-dependent Vacuum Contribution mentioning

confidence: 99%

General structure of the neutral ρ meson self-energy and its spectral properties in a hot and dense magnetized medium

et al. 2019

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“…Recently magnetic fields with very large coherence scale λ B 1 Mpc were detected in cosmic voids through the gamma-ray observations of distant blazars [1][2][3][4][5]. Combining the corresponding results with the data of the cosmic microwave background (CMB) [6][7][8][9][10] and ultra-high-energy cosmic rays [11] observations constrains the strength of these fields to 10 −18 B 10 −9 G. It is well known also that magnetic fields are present on much smaller scales in the Universe [10,[12][13][14][15][16][17][18] including galaxies and clusters of galaxies. Observed intergalactic magnetic fields may be of either astrophysical or primordial origin and both magnetogenesis scenarios are currently under active consideration and study.…”

Section: Introductionmentioning

confidence: 99%

Backreaction of electromagnetic fields and the Schwinger effect in pseudoscalar inflation magnetogenesis

2019

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We study magnetogenesis in axionlike inflation driven by a pseudoscalar field φ coupled axially to the electromagnetic (EM) field (β/Mp)φFµνF µν with dimensionless coupling constant β. A set of equations for the inflaton field, scale factor, and expectation values of quadratic functions of the EM field is derived. These equations take into account the Schwinger effect and the backreaction of generated EM fields on the Universe expansion. It is found that the backreaction becomes important when the EM energy density reaches the value ρEM ∼ ( √ 2 /β)ρ inf ( is the slow-roll parameter and ρ inf is the energy density of the inflaton) slowing down the inflaton rolling and terminating magnetogenesis. The Schwinger effect becomes relevant when the electric energy density exceeds the value ρE ∼ α −3 EM (ρ 2 tot /M 4 p ), where ρtot = 3H 2 M 2 p is the total energy density and αEM is the EM coupling constant. For large β, produced charged particles could constitute a significant part of the Universe energy density even before the preheating stage. Numerically studying magnetogenesis in the α-attractor model of inflation, we find that it is possible to generate helical magnetic fields with the maximal strength 10 −15 G, however, only with the correlation length of order 1 pc at present.

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“…The detection of magnetic fields in cosmic voids through the gamma-ray observations of distant blazars [1][2][3][4][5] is a remarkable discovery. Combining these observations with the data of the cosmic microwave background (CMB) [6][7][8][9][10] and ultra-high-energy cosmic rays [11] observations constrains the strength of these fields to 10 −18 B 10 −9 G. The extremely large coherence scale λ B 1 Mpc strongly suggests the cosmological origin of magnetic fields observed in voids. Thus, the study of such magnetic fields and their physical characteristics may shed light on the earliest stages of the Universe's history.…”

Section: Introductionmentioning

confidence: 83%

Kinetic approach to the Schwinger effect during inflation

et al. 2019

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Using the kinetic approach, we study the impact of the charged particle dynamics due to the Schwinger effect on the electric field evolution during inflation. As a simple model of the electric field generation, we consider the kinetic coupling of the electromagnetic field to the inflaton via the term f 2 (φ)Fµν F µν with the Ratra coupling function f = exp(βφ/Mp). The production of charged particles is taken into account in the Boltzmann kinetic equation through the Schwinger source term. Produced particles are thermalized due to collisions which we model by using the collision integral in the self-consistent relaxation time approximation. We found that the current of created particles exhibits a non-Markovian character and cannot be described by a simple Ohm's law relation j ∝ E. On the contrary, the electric current as well as the electric field are oscillatory functions of time with decreasing amplitudes and a phase difference due to the ballistic motion of charged carriers. Our qualitative results are checked by using a hydrodynamic approach. Deriving a closed system of equations for the number, current, and energy densities of charged particles and determining its solution, we find a good agreement with the results obtained in the kinetic approach.

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Probing large-scale magnetism with the cosmic microwave background

Cited by 25 publications

References 375 publications

General structure of the neutral ρ meson self-energy and its spectral properties in a hot and dense magnetized medium

General structure of the neutral ρ meson self-energy and its spectral properties in a hot and dense magnetized medium

Backreaction of electromagnetic fields and the Schwinger effect in pseudoscalar inflation magnetogenesis

Kinetic approach to the Schwinger effect during inflation

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