Large Scale Anisotropy Due to Pre-Inflationary Phase of Cosmic Evolution

Aluri, Pavan K.; Jain, Pankaj

doi:10.1142/s0217732312500149

Cited by 28 publications

(27 citation statements)

References 55 publications

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“…An interesting possibility is that there might have been a phase of anisotropic expansion at very early time. The inflationary Big Bang cosmology is perfectly consistent with such an evolution [52]. The anisotropic modes, generated during this early phase may later re-enter the horizon [52,53] and lead to the observed signals.…”

Section: Introductionsupporting

confidence: 63%

Noncommutative geometry and the primordial dipolar imaginary power spectrum

Jain

Rath

2015

Eur. Phys. J. C

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We argue that noncommutative space-times lead to an anisotropic dipolar imaginary primordial power spectrum. We define a new product rule, which allows us to consistently extract the power spectrum in such space-times. The precise nature of the power spectrum depends on the model of noncommutative geometry. We assume a simple dipolar model which has a power dependence on the wave number, k, with a spectral index, α. We show that such a spectrum provides a good description of the observed dipole modulation in the cosmic microwave background radiation (CMBR) data with α ≈ 0. We extract the parameters of this model from the data. The dipole modulation is related to the observed hemispherical anisotropy in the CMBR data, which might represent the first signature of quantum gravity.

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Section: Introductionsupporting

confidence: 63%

Noncommutative geometry and the primordial dipolar imaginary power spectrum

Jain

Rath

2015

Eur. Phys. J. C

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“…There are several non-conventional explanation for the NVSS dipole. For example, the anisotropic mode generated before inflation may re-enter the horizon at late time and produce large scale anisotropy [48][49][50]. Alternatively, the primordial non-Gaussianities (NG) may affect the structures at large scales.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Revisiting the NVSS number count dipole

Tiwari¹,

Nusser²

2016

J. Cosmol. Astropart. Phys.

101

122

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We present a realistic modeling of the dipole component of the projected sky distribution of NVSS radio galaxies. The modeling relies on mock catalogs generated within the context of ΛCDM cosmology, in the linear regime of structure formation. After removing the contribution from the solar motion, the mocks show that the remaining observed signal is mostly (70%) due to structures within z 0.1. The amplitude of the model signal depends on the bias factor b of the NVSS mock galaxies. For sources with flux density, S > 15 mJy, the bias recipe inferred from higher order moments is consistent with the observed dipole signal at 2.12σ. Flux thresholds above 20 mJy yield a disagreement close to the 3σ level. A constant high bias, b = 3 is needed to mitigate the tension to the ∼ 2.3σ level.

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“…It has been shown that, for a wide class of models, there exists a parameter range such that the modes generated during this early phase can re-enter the horizon much before the current era and hence can affect present observations. 18 These can, in principle, generate the observed anisotropies.…”

Section: Introductionmentioning

confidence: 98%

Polarization Alignment in Jvas/Class Flat Spectrum Radio Surveys

Tiwari

Jain

2013

Int. J. Mod. Phys. D

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We present a detailed statistical analysis of the alignment of polarizations of radio sources at high redshift. This study is motivated by the puzzling signal of alignment of polarizations from distant quasars at optical frequencies. We use a coordinate invariant measure of dispersion to test for alignment of polarizations of widely separated sources. The data from JVAS/CLASS 8.4 GHz surveys are used for our study. We find that the data set with polarization flux greater than 1 mJy shows a significant signal of alignment at distance scales of order 150 Mpc. The significance of alignment decreases as we go to larger distances. In contrast the data set with polarization flux less than 1 mJy does not show significant alignment at short distances. However this set, as well as the full data sample, shows a very significant signal at large distances of order 500-850 Mpc. Due to the presence of relatively large error in the low polarization sample, this signal needs to be tested further with more refined data. We also study the signal by imposing a cut on the error in polarization. We find that the significance of alignment increases with decrease in fractional error. We are unable to attribute our results to known sources of bias. We discuss a possible physical explanation of our results. Int. J. Mod. Phys. D 2013.22. Downloaded from www.worldscientific.com by CAMBRIDGE UNIVERSITY on 02/07/15. For personal use only. 1350089-3 Int. J. Mod. Phys. D 2013.22. Downloaded from www.worldscientific.com by CAMBRIDGE UNIVERSITY on 02/07/15. For personal use only.

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Large Scale Anisotropy Due to Pre-Inflationary Phase of Cosmic Evolution

Cited by 28 publications

References 55 publications

Noncommutative geometry and the primordial dipolar imaginary power spectrum

Noncommutative geometry and the primordial dipolar imaginary power spectrum

Revisiting the NVSS number count dipole

Polarization Alignment in Jvas/Class Flat Spectrum Radio Surveys

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