Isotropy analyses of the Planck convergence map

Abstract

The presence of matter in the path of relic photons causes distortions in the angular pattern of the cosmic microwave background (CMB) temperature fluctuations, modifying their properties in a slight but measurable way. Recently, the Planck Collaboration released the estimated convergence map, an integrated measure of the large-scale matter distribution that produced the weak gravitational lensing (WL) phenomenon observed in Planck CMB data. We perform exhaustive analyses of this convergence map calculating the variance in small and large regions of the sky, but excluding the area masked due to galactic contaminations, and compare them with the features expected in the set of simulated convergence maps, also released by the Planck collaboration. Our goal is to search for sky directions or regions where the WL imprints anomalous signatures to the variance estimator revealed through a χ 2 analyses at a statistically significant level. In the local analysis of the Planck convergence map we identified 8 patches of the sky in disagreement, in more than 2σ, with what is observed in the average of the simulations. In contrast, in the large regions analysis we found no statistically significant discrepancies, but, interestingly, the regions with the highest χ 2 values are surrounding the ecliptic poles. Thus, our results show a good agreement with the features expected by the ΛCDM concordance model, as given by the simulations. Yet, the outliers regions found here could suggest that the data still contain residual contamination, like noise, due to over-or under-estimation of systematic effects in the simulation data set.

The angular scale of homogeneity in the local Universe with the SDSS blue galaxies

“…The statistical isotropy of the universe is being tested for many extragalactic objects like Radio sources (Blake & Wall 2002;Ghosh et al 2016), Gamma-ray bursts (Bernui et al 2008a;Tarnopolski 2017;Řípa & Shafiello 2018), galaxy clusters (Bengaly et al 2017a), and galaxy datasets like the WISE (Yoon et al 2014;Bengaly et al 2017b;Novaes et al 2018) and the SDSS catalogues (Sarkar et al 2019), where all these analyses show a good concordance with the isotropy of the universe. The Planck Convergence and Cosmic Microwave Background temperature fluctuations maps have been examined and are also consistent with statistical isotropy at small angular scales (Ade et al 2016;Novaes et al 2016;Marques et al 2018), although some controversy remains at large angles (Bernui 2008b;Gruppuso et al 2013; Polase-mail: felipeavila@on.br tri, Gruppuso & Natoli 2015;Schwarz et al 2016;Aluri, Ralston & Weltman 2017;Rath et al 2017;Bernui et al 2018).…”

Local patch analysis for testing statistical isotropy of the Planck convergence map

“…Comparison of figure 6 with figs. 9 and 10 of [36] shows that there are some patches common, and both our analysis and theirs indicate that anomalous regions are more likely near the ecliptic poles and ecliptic plane.…”

“…Our local patch analysis is similar in spirit to the analysis carried out in Marques et al [36], though we use a different methodology. Their method uses the variance, and hence direct field values, computed from sky patches, while α is constructed using the first derivative of the field and can be directly interpreted as the anisotropy of a curve.…”

“…The assumption of SI of the CMB convergence field should be observationally verified since the detection of violation of SI could have profound implications for cosmology. Recently, Marques et al in [36] investigated SI of the Planck 2015 lensing convergence field using the local variance estimator, and identified sky directions or outlier regions where the weak lensing imprints anomalous signatures to the variance estimator revealed through a χ 2 analyses at a statistically significant level. The goal of this paper is to carry out similar analysis, but using a different methodology.…”

Tomographic analyses of the CMB lensing and galaxy clustering to probe the linear structure growth

“…The reconstructed map covers about f sky ∼ 67.3% of the sky, masking regions contaminated by Galaxy emissions and point sources. Jointly to the released lensing products, it is available the corresponding confidence mask and a set of 100 realistic simulations, which accurately incorporate the Planck noise levels and the κ statistical properties [52]. The maps as well as the mask are provided in the HEALPix resolution parameter N side = 2048.…”