2025/06/10 by Frode K. Hansen, D. G. Lambas, Hansen, Frode K. +7 · 2 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Astronomy and Astrophysical Research
paper · pdf · doi:10.48550/arxiv.2506.08832
We find a significant CMB temperature excess in the direction of local underdensities within z<0.03. By contrast, less than 0.2% of simulated CMB maps show a similarly significant temperature excess in nearby voids. Combined with earlier findings showing a >5σ cooling of CMB photons in galactic filaments in the same redshift range, we now may have possible evidence for a negative Integrated Sachs-Wolfe (ISW) effect in the very recent Universe. In addition to having opposite sign, the observed amplitude is an order of magnitude larger than the predicted Rees-Sciama and ISW effects, pointing to an unknown physical process, possibly related with a non-standard model of dark energy. We discuss the results in light of the latest Data Release 2 results of the Dark Energy Spectroscopic Instrument (DESI) showing hints for dynamical dark energy. Removing the quadrupole, we find the CMB temperatures measured in nearby voids to a large degree uncorrelated with the temperature measured around nearby galaxies and the observed mean difference between these temperatures is almost 6.5σ larger than found in simulations.