CMB temperature anisotropy from broken spatial isotropy due to a homogeneous cosmological magnetic field

Kahniashvili, Tina; Lavrelashvili, George; Ratra, Bharat

doi:10.1103/physrevd.78.063012

Cited by 79 publications

(60 citation statements)

References 89 publications

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“…Note however that inflationary models with vector fields usually suffer from instabilities due to the existence of ghosts. [59] • The existence of a large scale primordial magnetic field [60][61][62]. Evidence for such a magnetic field has recently been found in CMB maps [63].…”

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confidence: 99%

Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes

Antoniou

Perivolaropoulos

2010

J. Cosmol. Astropart. Phys.

158

227

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We review, compare and extend recent studies searching for evidence for a preferred cosmological axis. We start from the Union2 SnIa dataset and use the hemisphere comparison method to search for a preferred axis in the data. We find that the hemisphere of maximum accelerating expansion rate is in the direction (l, b) = (309•+11• −10 • ) (Ω0m = 0.19) while the hemisphere of minimum acceleration is in the opposite direction (l, b) = (129The level of anisotropy is described by the normalized difference of the best fit values of Ω0m between the two hemispheres in the context of ΛCDM fits. We find a maximum anisotropy level in the Union2 data of= 0.43 ± 0.06. Such a level does not necessarily correspond to statistically significant anisotropy because it is reproduced by about 30% of simulated isotropic data mimicking the best fit Union2 dataset. However, when combined with the axes directions of other cosmological observations (bulk velocity flow axis, three axes of CMB low multipole moments and quasar optical polarization alignment axis), the statistical evidence for a cosmological anisotropy increases dramatically. We estimate the probability that the above independent six axes directions would be so close in the sky to be less than 1%. Thus either the relative coincidence of these six axes is a very large statistical fluctuation or there is an underlying physical or systematic reason that leads to their correlation.

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confidence: 99%

Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes

Antoniou

Perivolaropoulos

2010

J. Cosmol. Astropart. Phys.

158

227

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“…Likewise, models predicting a covariance matrix of the form a 1m1 a * 2m2 = f ( 1 , m 1 )δ 1 2 δ m1m2±p , such as happens with CMB in the presence of a homogeneous magnetic field [51], will lead to …”

Section: Anisotropies Through Planar Modulationsmentioning

confidence: 99%

“…However, if there are departures from statistical isotropy, either of systematic [17], astrophysical [19][20][21] or cosmological [16,[22][23][24] origin, the two-point correlation function (2pcf) will depend on other angles relatingn and n ; in this case, C(θ) no longer exhausts the statistics of the universe. Thus, if we want to go beyond the ΛCDM framework, the central question is how to parameterize deviations from Eq.…”

Section: Introductionmentioning

confidence: 99%

New geometric representations of the CMB two-point correlation function

et al. 2015

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When searching for deviations of statistical isotropy in CMB, a popular strategy is to write the two-point correlation function (2pcf) as the most general function of four spherical angles (i.e., two unit vectors) in the celestial sphere. Then, using a basis of bipolar spherical harmonics, statistical anisotropy will show up if and only if any coefficient of the expansion with non-trivial bipolar momentum is detected -although this detection will not in general elucidate the origin of the anisotropy. In this work we show that two new sets of four angles and basis functions exist which completely specifies the 2pcf, while, at the same time, offering a possible geometrical interpretation of the mechanisms generating the signal. Since the coefficients of these expansions are zero if and only if isotropy holds, they act as a simple and geometrically motivated null test of statistical isotropy, with the advantage of allowing cosmic variance to be controlled in a systematic way. We report the results of the application of these null tests to the latest temperature data released by the Planck collaboration.

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“…Such a seed field can be produced by the inflation [3,4,5], or by the electroweak phase transition (EPT) [6,7,8]. In the past, PMF has been constrained mainly by using their various effects on cosmic microwave background (CMB) anisotropies and polarization [9,10,11,12,13,14]. Based on the Faraday rotation of CMB linear polarization caused by PMF, Kahniashvili et al [15] utilized the 5-year WMAP (WMAP5) B-mode polarization limit to give an upper limit on the amplitude of PMF: B λ ≤ 6 × 10 −8 Gauss on a scale λ = 1 Mpc.…”

Section: Introductionmentioning

confidence: 99%

New primordial-magnetic-field limit from the latest LIGO S5 data

Wang

2010

Phys. Rev. D

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Since the energy momentum tensor of a magnetic field always contains a spin-2 component in its anisotropic stress, stochastic primordial magnetic field (PMF) in the early universe must generate stochastic gravitational wave (GW) background. This process will greatly affect the relic gravitational wave (RGW), which is one of major scientific goals of the laser interferometer GW detections. Recently, the fifth science (S5) run of laser interferometer gravitational-wave observatory (LIGO) gave a latest upper limit Ω GW < 6.9 × 10 −6 on the RGW background.Utilizing this upper limit, we derive new PMF Limits: for a scale of galactic cluster λ = 1 Mpc, the amplitude of PMF, that produced by the electroweak phase transition (EPT), has to be weaker than B λ ≤ 4 × 10 −7 Gauss; for a scale of supercluster λ = 100 Mpc, the amplitude of PMF has to be weaker than B λ ≤ 9 × 10 −11 Gauss. In this manner, GW observation has potential to make interesting contributions to the study of primordial magnetic field.

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CMB temperature anisotropy from broken spatial isotropy due to a homogeneous cosmological magnetic field

Abstract: We derive the cosmic microwave background temperature anisotropy two-point correlation function (including off-diagonal correlations) from broken spatial isotropy due to an arbitrarily oriented homogeneous cosmological magnetic field.

Cited by 79 publications

References 89 publications

Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes

Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes

New geometric representations of the CMB two-point correlation function

New primordial-magnetic-field limit from the latest LIGO S5 data

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