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Author: search.filters.author.Kranas, D.

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    Large scale anomalies in the CMB and non-Gaussianity in bouncing cosmologies
    (IOP Publishing Ltd, 2021) Agullo, I.; Kranas, D.; Sreenath, V.
    We propose that several of the anomalies that have been observed at large angular scales in the CMB have a common origin in a cosmic bounce that took place before the inflationary era. The bounce introduces a new physical scale in the problem, which breaks the almost scale invariance of inflation. As a result, the state of scalar perturbations at the onset of inflation is no longer the Bunch–Davies vacuum, but it rather contains excitations and non-Gaussianity, which are larger for infrared modes. We argue that the combined effect of these excitations and the correlations between CMB modes and longer wavelength perturbations, can account for the observed power suppression, for the dipolar asymmetry, and it can also produce a preference for odd-parity correlations. The model can also alleviate the tension in the lensing amplitude AL. We adopt a phenomenological viewpoint by considering a family of bounces characterized by a couple of parameters. We identify the minimum set of ingredients needed for our ideas to hold, and point out examples of theories in the literature where these conditions are met. © 2021 IOP Publishing Ltd Printed in the UK
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    Anomalies in the Cosmic Microwave Background and Their Non-Gaussian Origin in Loop Quantum Cosmology
    (Frontiers Media S.A., 2021) Agullo, I.; Kranas, D.; Sreenath, V.
    Anomalies in the cosmic microwave background (CMB) refer to features that have been observed, mostly at large angular scales, and which show some tension with the statistical predictions of the standard ?CDM model. In this work, we focus our attention on power suppression, dipolar modulation, a preference for odd parity, and the tension in the lensing parameter AL. Though the statistical significance of each individual anomaly is inconclusive, collectively they are significant, and could indicate new physics beyond the ?CDM model. In this article, we present a brief, but pedagogical introduction to CMB anomalies and propose a common origin in the context of loop quantum cosmology. © Copyright © 2021 Agullo, Kranas and Sreenath.