Faraday rotation of the cosmic microwave background polarization by a stochastic magnetic field

Kosowsky, Arthur; Kahniashvili, Tina; Lavrelashvili, George; Ratra, Bharat

doi:10.1103/physrevd.71.043006

Cited by 153 publications

(205 citation statements)

References 63 publications

(103 reference statements)

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“…We are mainly interested in constraints from CMB temperature anisotropies. Therefore, we do not consider the effect of Faraday rotation on CMB polarization anisotropies (Kosowsky & Loeb 1996;Kosowsky et al 2005) nor non-Gaussianities associated with PMF (Brown & Crittenden 2005;Caprini et al 2009;Seshadri & Subramanian 2009;Trivedi et al 2010). We restrict the analysis reported here to the non-helical case.…”

Section: Constraints On a Stochastic Background Of Primordial Magnetimentioning

confidence: 99%

Planck2013 results. XVI. Cosmological parameters

Ade¹,

Aghanim²,

Armitage-Caplan³

et al. 2014

A&A

5,074

163

2,253

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This paper presents the first cosmological results based on Planck measurements of the cosmic microwave background (CMB) temperature and lensing-potential power spectra. We find that the Planck spectra at high multipoles ( > ∼ 40) are extremely well described by the standard spatiallyflat six-parameter ΛCDM cosmology with a power-law spectrum of adiabatic scalar perturbations. Within the context of this cosmology, the Planck data determine the cosmological parameters to high precision: the angular size of the sound horizon at recombination, the physical densities of baryons and cold dark matter, and the scalar spectral index are estimated to be θ * = (1.04147 ± 0.00062) × 10 −2 , Ω b h 2 = 0.02205 ± 0.00028, Ω c h 2 = 0.1199 ± 0.0027, and n s = 0.9603 ± 0.0073, respectively (note that in this abstract we quote 68% errors on measured parameters and 95% upper limits on other parameters). For this cosmology, we find a low value of the Hubble constant, H 0 = (67.3 ± 1.2) km s −1 Mpc −1 , and a high value of the matter density parameter, Ω m = 0.315 ± 0.017. These values are in tension with recent direct measurements of H 0 and the magnituderedshift relation for Type Ia supernovae, but are in excellent agreement with geometrical constraints from baryon acoustic oscillation (BAO) surveys. Including curvature, we find that the Universe is consistent with spatial flatness to percent level precision using Planck CMB data alone. We use high-resolution CMB data together with Planck to provide greater control on extragalactic foreground components in an investigation of extensions to the six-parameter ΛCDM model. We present selected results from a large grid of cosmological models, using a range of additional astrophysical data sets in addition to Planck and high-resolution CMB data. None of these models are favoured over the standard six-parameter ΛCDM cosmology. The deviation of the scalar spectral index from unity is insensitive to the addition of tensor modes and to changes in the matter content of the Universe. We find an upper limit of r 0.002 < 0.11 on the tensor-to-scalar ratio. There is no evidence for additional neutrino-like relativistic particles beyond the three families of neutrinos in the standard model. Using BAO and CMB data, we find N eff = 3.30 ± 0.27 for the effective number of relativistic degrees of freedom, and an upper limit of 0.23 eV for the sum of neutrino masses. Our results are in excellent agreement with big bang nucleosynthesis and the standard value of N eff = 3.046. We find no evidence for dynamical dark energy; using BAO and CMB data, the dark energy equation of state parameter is constrained to be w = −1.13 +0.13 −0.10 . We also use the Planck data to set limits on a possible variation of the fine-structure constant, dark matter annihilation and primordial magnetic fields. Despite the success of the six-parameter ΛCDM model in describing the Planck data at high multipoles, we note that this cosmology does not provide a good fit to the temperature power spectrum at low multipoles. T...

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Section: Constraints On a Stochastic Background Of Primordial Magnetimentioning

confidence: 99%

Planck2013 results. XVI. Cosmological parameters

Ade¹,

Aghanim²,

Armitage-Caplan³

et al. 2014

A&A

5,074

163

2,253

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“…At much higher redshifts, RMs may be detectable against the polarised signal from the cosmic microwave background (e.g., Kosowsky et al 2005). However, this experiment could be challenging, because of the small position angle changes expected at high frequencies (ν > 20 GHz).…”

Section: Magnetic Fields At High Redshiftmentioning

confidence: 99%

The Square Kilometre Array: a new probe of cosmic magnetism

Gaensler

2006

Astron Nachr

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Magnetic fields are a fundamental part of many astrophysical phenomena, but the evolution, structure and origin of magnetic fields are still unresolved problems in physics and astrophysics. When and how were the first fields generated? Are present-day magnetic fields the result of standard dynamo action, or do they represent rapid or recent field amplification through other processes? What role do magnetic fields play in turbulence, cosmic ray acceleration and structure formation? I explain how the Square Kilometre Array (SKA), a next-generation radio telescope, can deliver stunning new data-sets that will address these currently unanswered issues. The foundation for these experiments will be an all-sky survey of rotation measures, in which Faraday rotation toward > 10 7 background sources will provide a dense grid for probing magnetism in the Milky Way, nearby galaxies, and in distant galaxies, clusters and protogalaxies. Using these data, we can map out the evolution of magnetized structures from redshifts z > 3 to the present, can distinguish between different origins for seed magnetic fields in galaxies, and can develop a detailed model of the magnetic field geometry of the intergalactic medium and of the overall Universe. In addition, the SKA will certainly discover new magnetic phenomena beyond what we can currently predict or imagine.

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“…For example, Faraday rotation only provides an estimate of the line of sight component of the magnetic field. Even by observing the Faraday rotation from different sources, the information is insufficient to estimate the helicity [16,17,18]. An estimate of the helicity necessarily requires sensitivity to all components of the magnetic field and hence it is a challenging theoretical problem to devise means by which it may be measured.…”

mentioning

confidence: 99%

Detection of magnetic helicity

Kahniashvili

Vachaspati

2006

Phys. Rev. D

Self Cite

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Magnetic fields in various astrophysical settings may be helical and, in the cosmological context, may provide a measure of primordial CP violation during baryogenesis. Yet it is difficult, even in principle, to devise a scheme by which magnetic helicity may be detected, except in some very special systems. We propose that charged cosmic rays originating from known sources may be useful for this purpose. We show that the correlator of the arrival momenta of the cosmic rays is sensitive to the helicity of an intervening magnetic field. If the sources themselves are not known, the method may still be useful provided we have some knowledge of their spatial distribution.PACS numbers: 98.80. Cq, 98.62.En Magnetic fields pervade all astrophysical objects [1,2] and there are good theoretical reasons to believe that a weak magnetic field is present throughout the universe. In astrophysical systems the magnetic field is often helical which means that the field lines are twisted (like corkscrews), or that closed magnetic lines are linked. Mathematically, the average helicity density in a volume V is defined as:In cosmology, a number of scenarios predict the creation of a primordial field with non-zero helicity. In the scenario discussed in Refs. [3,4,5,6], a magnetic field is produced at the electroweak phase transition. The helicity of the magnetic field is related to the cosmological baryon asymmetry arising from CP violation in the fundamental particle physics theory, and the sign of the helicity is predicted to be left-handed [6]. There are also several other scenarios for the generation of primordial helical magnetic fields that do not depend on the dynamics through a phase transition [7,8,9,10,11,12,13]. The helicity of magnetic fields in astrophysical jets can be deduced from the polarization of synchrotron radiation [14,15]. In such situations, the velocity of electrons in the jets is known and this additional information is crucial to the determination of helicity. In other situations, it is much harder to find the helicity. For example, Faraday rotation only provides an estimate of the line of sight component of the magnetic field. Even by observing the Faraday rotation from different sources, the information is insufficient to estimate the helicity [16,17,18]. An estimate of the helicity necessarily requires sensitivity to all components of the magnetic field and hence it is a challenging theoretical problem to devise means by which it may be measured. In Ref. [19,20,21] the imprint of cosmological magnetic helicity in parity-odd cross correlations of the cosmic microwave background (CMB) fluctuations was investigated, while in Ref. [22] it was shown that helicity would introduce circular polarization of induced relic gravitational waves. Both these potential signatures of helicity are limited to cosmological magnetic fields since they rely on properties of the cosmic microwave background or on the cosmic gravitational wave background. Further, the signals are small for several reasons: the cosmic magnetic f...

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Faraday rotation of the cosmic microwave background polarization by a stochastic magnetic field

Cited by 153 publications

References 63 publications

Planck2013 results. XVI. Cosmological parameters

Planck2013 results. XVI. Cosmological parameters

The Square Kilometre Array: a new probe of cosmic magnetism

Detection of magnetic helicity

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