Abstract
ABSTRACT Although the search for azimuthal patterns in cosmological surveys is useful to characterize some effects depending exclusively on an angular distance within the standard model, they are considered as a key distinguishing feature of some exotic scenarios, such as bubble collisions or conformal cyclic cosmology (CCC). In particular, the CCC is a non-stardard framework that predicts circular patterns on the cosmic microwave background intensity fluctuations. Motivated by some previous works that explore the presence of radial gradients, we apply a methodology based on the radial derivatives to the latest release of Planck data. The new approach allows exhaustive studies to be performed at all-sky directions at a healpix resolution of Nside = 1024. Specifically, two different analyses are performed focusing on weight functions in both small (up to a 5-deg radius) and large scales. We present a comparison between our results and those shown by An, Meissner & Nurowski (2017) and An et al. (2018). In addition, a possible polarization counterpart of these circular patterns is also analysed for the most promising case. Taking into account the limitations to characterize the significance of the results, including the possibility of suffering a look-elsewhere effect, no strong evidence of the kind of circular patterns expected from CCC is found in the Planck data for either the small or the large scales.
Highlights
A usual way of testing the standard model of cosmology is to confront the data to alternative models and scenarios that provide a distinguishing prediction
Taking into account the limitations to characterize the significance of the results, including the possibility of suffering a look-elsewhere effect, no strong evidence of the kind of circular patterns expected from cyclic cosmology (CCC) is found in the Planck data for either the small or the large scales
We have reviewed some of the most recent results in the literature regarding the presence of ring-type structures in the cosmic microwave background (CMB) fluctuations such as those predicted by the CCC
Summary
A usual way of testing the standard model of cosmology is to confront the data to alternative models and scenarios that provide a distinguishing prediction. In the first one, An et al (2017) look for the presence of circles in the large-scale CMB field using the differences of the mean intensity between adjacent rings They find an anomalous scale around 8 deg of radius at a 99.6 per cent confidence level, they admit that this statistical significance is possibly overrated in light of a potential look-elsewhere effect. In a second paper, An et al (2018) explore the scales up to a 5-deg radius computing the radial slope inside the rings, finding evidence of an anomalous detection at a 99.98 per cent confidence level In another recent paper, Jow & Scott (2020) revisit the evidence of radial gradients, including a polarization analysis.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call