The cosmic microwave background Cold Spot anomaly: the impact of sky masking and the expected contribution from the Integrated Sachs-Wolfe effect

Abstract

We re-analyse the cosmic microwave background (CMB) Cold Spot (CS) anomaly with particular focus on understanding the bias a mask (contaminated by Galactic and point sources) may introduce. We measure the coldest spot, found by applying the Spherical Mexican Hat Wavelet transform on 100 000 cut-sky (masked) and full-sky CMB simulated maps. The CS itself is barely affected by the mask; we estimate a 94 per cent probability that the CS is the full-sky temperature minimum. However, approximately 48 per cent (masked fraction of the mask) of full-sky minima are obscured by the mask. Since the observed minima are slightly hotter than the full-sky ensemble of minima, a cut-sky analysis would have found the CS to be significant at approximately 2.2 sigma with a wavelet angular scale of R = 5 degrees. None the less, comparisons to full-sky minima show the CS significance to be only approximately 1.9 sigma and less than 2 sigma for all R. The CS on the last scattering surface may be hotter due to the integrated Sachs-Wolfe effect in the line of sight. However, our simulations show that this on average only approximately 10 per cent (about 10 micro K but consistent with zero) of the CS temperature profile. This is consistent with Lambda and cold dark matter reconstructions of this effect based on observed line-of-sight voids.

6 pages, 5 figures, changes made to match version published in MNRAS

References in corpus (15)

• Planck 2018 results. VII. Isotropy and Statistics of the CMB
• An Imprint of Super-Structures on the Microwave Background due to the Integrated Sachs-Wolfe Effect
• The non-Gaussian Cold Spot in the 3-year WMAP data
• Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies I
• Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies: The Effect of a Cosmological Constant
• Detection of a Supervoid Aligned with the Cold Spot of the Cosmic Microwave Background
• A detection of the integrated Sachs-Wolfe imprint of cosmic superstructures using a matched-filter approach
• Can a supervoid explain the Cold Spot?
• Imprint of DES super-structures on the Cosmic Microwave Background
• The Jubilee ISW Project II: observed and simulated imprints of voids and superclusters on the cosmic microwave background
• Evidence against a supervoid causing the CMB Cold Spot
• Planck CMB Anomalies: Astrophysical and Cosmological Secondary Effects and the Curse of Masking
• The part and the whole: voids, supervoids, and their ISW imprint
• Comment on "A Supervoid Imprinting the Cold Spot in the Cosmic Microwave Background"
• Multiscale analysis of the CMB temperature derivatives

Cited by in corpus (10)

• The Void Size Function in Dynamical Dark Energy Cosmologies
• More out of less: an excess integrated Sachs-Wolfe signal from supervoids mapped out by the Dark Energy Survey
• The DES view of the Eridanus supervoid and the CMB Cold Spot
• Cosmicflows-3: Cold Spot Repeller?
• Dark matter solution to the $H_0$ and $S_8$ tensions, and the integrated Sachs-Wolfe void anomaly
• A common explanation of the Hubble tension and anomalous cold spots in the CMB
• Accelerated expansion of the universe and chasing photons from the CMB to study the late time integrated Sachs-Wolfe effect over different redshift ranges
• The CMB cold spot under the lens: ruling out a supervoid interpretation
• Full sky Integrated Sachs-Wolfe maps for the MICE Grand Challenge lightcone simulation
• Learning sparse representations on the sphere