Cosmic microwave background quadrupole and ellipsoidal universe

Campanelli, Leonardo; Cea, Paolo; Tedesco, Luigi

doi:10.1103/physrevd.76.063007

Cited by 192 publications

(204 citation statements)

References 83 publications

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“…This is still significantly weaker than the ISW bound considered in [31][32][33]. Due to the prohibitive nature of the CMB limit for anisotropic expansion, barring fine tuning, in what follows we fix the global dynamics as isotropic and explore possible local, line of sight effects (including those due to systematics).…”

Section: Supernova Constraints On Anisotropic Expansionmentioning

confidence: 99%

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Probing dark energy anisotropy

Appleby

Linder

2013

Phys. Rev. D

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Wide area cosmological surveys enable investigation of whether dark energy properties are the same in different directions on the sky. Cosmic microwave background observations strongly restrict any dynamical effects from anisotropy, in an integrated sense. For more local constraints we compute limits from simulated distance measurements for various distributions of survey fields in a Bianchi I anisotropic universe. We then consider the effects of fitting for line of sight properties where isotropic dynamics is assumed (testing the accuracy through simulations) and compare sensitivities of observational probes for anisotropies, from astrophysical systematics as well as dark energy. We also point out some interesting features of anisotropic expansion in Bianchi I cosmology.

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Section: Supernova Constraints On Anisotropic Expansionmentioning

confidence: 99%

“…Cosmological models containing a global anisotropy, such as this Bianchi model, are severely constrained by observations [27][28][29][30], specifically the integrated SachsWolfe effect on the CMB [31][32][33]. Illustratively, the temperature anisotropy arises as…”

Section: Exact Solution: Bianchi I Cosmologymentioning

confidence: 99%

Probing dark energy anisotropy

Appleby

Linder

2013

Phys. Rev. D

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“…While there are many ways suggested to handle the issue of global anisotropy, the flat Friedman model (FRW) can be suitably modified to incorporate the anisotropic effect. In recent times, some anisotropic models bearing similarity to Bianchi morphology have been proposed [63][64][65][66][67]. In this context, it is interesting to investigate some anisotropic models in the framework of f (R) gravity.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic solutions in f(R) gravity

Tripathy

Mishra

2016

Eur. Phys. J. Plus

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Anisotropic cosmological models are investigated in the frame work of f (R) gravity in the metric formalism. Plane symmetric models are considered to incorporate anisotropy in the expansion rates along different spatial directions. The anisotropy in expansion rates are assumed to be maintained throughout the cosmic evolution. Two accelerating models are constructed by considering different functional forms for f (R). The viability of these models are tested through a stability analysis.

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“…The most important limits came from the study of Big Bang Nucleosynthesis [113][114][115][116][117][118][119][120] and Cosmic Microwave Background (CMB) anisotropies ( [121][122][123]. For a review of the effects of large-scale magnetic fields on the cosmic microwave background radiation, see [124]; see also [125][126][127][128][129][130][131][132][133][134][135]. In particular, large-scale, primordial helical magnetic fields could leave peculiar signatures in the CMB radiation [136][137][138], since they would introduce parity-odd crosscorrelations of the CMB anisotropies not present in the case of a non-helical magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Evolution of primordial magnetic fields in mean-field approximation

Campanelli

2014

Eur. Phys. J. C

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We study the evolution of phase-transitiongenerated cosmic magnetic fields coupled to the primeval cosmic plasma in the turbulent and viscous free-streaming regimes. The evolution laws for the magnetic energy density and the correlation length, both in the helical and the non-helical cases, are found by solving the autoinduction and Navier-Stokes equations in the mean-field approximation. Analytical results are derived in Minkowski spacetime and then extended to the case of a Friedmann universe with zero spatial curvature, both in the radiation-and the matterdominated era. The three possible viscous free-streaming phases are characterized by a drag term in the Navier-Stokes equation which depends on the free-streaming properties of neutrinos, photons, or hydrogen atoms, respectively. In the case of non-helical magnetic fields, the magnetic intensity B and the magnetic correlation length ξ B evolve asymptotically with the temperature, T , asHere, T i , N i , and v i are, respectively, the temperature, the number of magnetic domains per horizon length, and the bulk velocity at the onset of the particular regime. The coefficients κ B , κ ξ , 1 , 2 , 3 , and 4 , depend on the index of the assumed initial power-law magnetic spectrum, p, and on the particular regime, with the order-one constants κ B and κ ξ depending also on the cutoff adopted for the initial magnetic spectrum. In the helical case, the quasi-conservation of the magnetic helicity implies, apart from logarithmic corrections and a factor proportional to the initial fractional helicity, power-like evolution laws equal to those in the non-helical case, but with p equal to zero.

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Cosmic microwave background quadrupole and ellipsoidal universe

Cited by 192 publications

References 83 publications

Probing dark energy anisotropy

Probing dark energy anisotropy

Anisotropic solutions in f(R) gravity

Evolution of primordial magnetic fields in mean-field approximation

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