The CMB cold spot under the lens: ruling out a supervoid interpretation
Abstract
The Cosmic Microwave Background (CMB) anisotropies are thought to be statistically isotropic and Gaussian. However, several anomalies are observed, including the CMB Cold Spot, an unexpected cold ~ 10° region with p-value ≲ 0.01 in standard ΛCDM. One of the proposed origins of the Cold Spot is an unusually large void on the line of sight, that would generate a cold region through the combination of integrated Sachs-Wolfe and Rees-Sciama effects. In the past decade extensive searches were conducted in large scale structure surveys, both in optical and infrared, in the same area for z ≲ 1 and did find evidence of large voids, but of depth and size able to account for only a fraction of the anomaly. Here we analyze the lensing signal in the Planck CMB data and rule out the hypothesis that the Cold Spot could be due to a large void located anywhere between us and the surface of last scattering. In particular, computing the evidence ratio we find that a model with a large void is disfavored compared to ΛCDM, with odds 1 : 13 (1 : 20) for SMICA (NILC) maps, compared to the original odds 56 : 1 (21 : 1) using temperature data alone.
- Publication:
-
Journal of Cosmology and Astroparticle Physics
- Pub Date:
- June 2023
- DOI:
- 10.1088/1475-7516/2023/06/040
- arXiv:
- arXiv:2211.16139
- Bibcode:
- 2023JCAP...06..040O
- Keywords:
-
- gravitational lensing;
- integrated Sachs-Wolfe effect;
- cosmic web;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- v2: typos corrected in some equations