Cosmic filaments confirm unexplained CMB temperature decrements in two independent redshift ranges

TL;DR

This study detects a consistent CMB temperature decrement along cosmic filaments across two redshift ranges, supporting the existence of an unexplained cooling effect linked to filament properties.

Contribution

First demonstration of CMB temperature decrement along filaments at higher redshifts using mean profiles and filament orientation analysis.

Findings

3-4 sigma detection of temperature decrement trend

Stronger decrement with increased filament mass and radial orientation

Effect observed consistently in two independent redshift ranges

Abstract

Recent papers have reported an unexplained cooling of CMB photons passing through galaxies in nearby cosmic filaments $z<0.02$ at the $>5\sigma$ level. Here we show for the first time that this effect is also present at higher redshifts $0.02<z<0.04$. Instead of calculating the CMB temperature around individual galaxies as in previous works, we analyze mean CMB temperature profiles associated to cosmic filaments in three dimensions. We have considered different thresholds in the linear K-band luminosity density of the filaments as a proxy to mass density. Furthermore, we have analyzed the dependence of the results on the average orientation of filaments with respect to the line of sight. These studies were implemented to test the expected dependence on mass density as well as on photon trajectory length within the cosmic filaments. We find a $3-4\sigma$ detection of a CMB temperature decrement trend towards the spine of the filaments, the larger the mass and the more radially oriented the filament, the stronger the CMB temperature decrement. This trend is seen independently in both redshift ranges $0.004<z<0.02$ and $0.02<z<0.04$. We therefore conclude that our results provide strong evidence for a lower CMB temperature along massive cosmic filaments in the nearby universe $z<0.04$.