Probing CMB Cold Spot through Local Minkowski Functionals

TL;DR

This study investigates the Cold Spot in the CMB using local Minkowski functionals, revealing significant non-Gaussianity and suggesting cosmic texture as a plausible explanation, with implications for future polarization data analysis.

Contribution

The paper introduces local Minkowski functionals to analyze the Cold Spot's non-Gaussianity and demonstrates cosmic texture as a potential cause, supported by statistical significance.

Findings

WMAP Cold Spot deviates from Gaussianity at over 99% confidence level

Third Minkowski function $ u_2$ is highly sensitive to non-Gaussianity

Cosmic texture explains the anomalies related to the Cold Spot

Abstract

Both WMAP and PLANCK missions reported the extremely Cold Spot (CS) centered at Galactic coordinate ($l=209^{\circ}$, $b=-57^{\circ}$) in CMB map. In this paper, we study the local non-Gaussianity of CS by defining the local Minkowski functions. We find that the third Minkowski function $\nu_2$ is quite sensitive to the non-Gaussianity caused by CS. Compared with the random Gaussian simulations, WMAP CS deviates from Gaussianity at more than 99% confident level at the scale $R\sim10^{\circ}$. Meanwhile, we find that cosmic texture provides an excellent explanation for these anomalies related to WMAP CS, which could be further tested by the future polarization data.