Unexplained correlation between the Cosmic Microwave Background temperature and the local matter density distribution

TL;DR

This paper investigates a potential correlation between the CMB temperature decrement and local matter density, finding significant evidence for a local-scale correlation possibly linked to dark matter, using multiple analytical methods.

Contribution

It provides the first multi-method analysis confirming a local correlation between CMB temperature and matter density, challenging previous assumptions about foreground contamination.

Findings

Significant correlation at distances below 50 Mpc/h

Correlation not detected beyond 50 Mpc/h

Supports dark matter halo connection hypothesis

Abstract

Recent observations have indicated a Cosmic Microwave Background (CMB) temperature decrement in the direction of local galaxies within the 2MASS Redshift Survey. We investigate this detection by analyzing its frequency dependence and sensitivity to component separation methods, suggesting that Galactic foregrounds are unlikely to be the cause. Contrary to previous studies, we find that the decrement is independent of galaxy type, indicating a possible correlation between the CMB and the overall matter density field. To test this hypothesis, we employ three analytical approaches: cross-correlation analysis, template fitting, and Bayes Factor calculation. Our cross-correlation analysis shows a significant correlation (p < 0.7%) between the CMB and the 2MASS Redshift Survey projected matter density at distances below 50 Mpc/h. Template fitting and Bayes Factor analyses support this finding, albeit with lower significance levels (1% - 5%). Importantly, we do not detect this signal beyond 50 Mpc/h, which constrains potential physical interpretations. We discuss that the physical origin of this correlation could potentially be linked to the dark matter distribution in the halos of galaxies. Further investigation is required to confirm and understand this intriguing connection between the CMB and local matter distribution.