The Cosmic Background Radiation measured by the Planck collaboration should be a lot hotter than what is observed around nearby spiral galaxies, compared to what is predicted in the ΛCDM model (a.k.a. the Standard Model of Cosmology) and is much more correlated with the ultra-large scale cosmic filament structure of the universe than the ΛCDM model predicts as well. This means a couple of things:
* The ΛCDM model has added one more problem to its dozens of existing conflicts with observational evidence. The only reasons that it is still used is that it is simple, and there is no consensus alternative.
* The inferences made from the CMB background may be subject to a pervasive source of highly significant systemic error that is not yet well understood. This could impact all sorts of cosmology "facts" based upon these systemically incorrectly measured parameters. These errors could also be a source of some key tensions in current cosmology measurements.
* The problem with trying to explain this with a physical mechanism related to dark matter is that dark matter effects are already deeply integrated into the ΛCDM model.
We confirm at the 5.7σ level previous studies reporting Cosmic Microwave Background (CMB) temperatures being significantly lower around nearby spiral galaxies than expected in the ΛCDM model. The significance reported in our earlier work was disputed by Addison 2024, who reported lower signficances when including pixels at distances far beyond the galactic halos while disregarding pixels close to the galaxies where the main signal is seen. Here we limit the study to pixels well within the galactic halos, focus on galaxies in dense cosmic filaments and improve on signal-to-noise compared to previous studies.
The average CMB temperature in discs around these galaxies is always much lower in Planck data than in any of the 10.000 Planck-like CMB simulations. Even when correcting for the look-elsewhere-effect, the detection is still at the 3−4σ level. We further show that the largest scales (ℓ<16) of the Planck CMB fluctuations are more correlated with the distribution of nearby galaxies than 99.99% of simulated CMB maps.
We argue that the existence of a new CMB foreground cannot be ignored and a physical interaction mechanism, possibly involving dark matter, as well as linked to intergalactic magnetic fields, should be sought.
Frode K. Hansen, et al., "A 5.7σ detection confirming the existence of a possibly dark matter related CMB foreground in nearby cosmic filaments" arXiv:2411.15307 (November 22, 2024).
Important if true. But what is the actual effect? In the discussion they describe it thus:
ReplyDelete"an unknown process removing or cooling CMB photons in and around galaxies"
I'm not 100% sure, but I assume this means CMB photons that pass through/near the galaxy, rather than CMB photons which originate from the galaxy's protogalaxy precursor.