Global Anisotropies of $\Omega_\Lambda$

TL;DR

This study identifies large-scale anisotropies in the measurement of the cosmological constant using supernova data, suggesting potential systematic effects or relativistic frame influences rather than true dark energy variations.

Contribution

It reveals two significant anisotropies in $\

Findings

Detected large-scale asymmetries in $\

contribution

It reveals two significant anisotropies in $\

Abstract

An analysis of the Cosmological Constant $\Omega_\Lambda$ fitted to subsamples of the Pantheon+ Type Ia SN sample spanning 2$\pi$ sterradians for a grid of 432 pole positions covering the whole sky reveals two large scale asymmetries. One of them is closely aligned with the Galactic North-South direction and the other points approximately towards RA$\sim 217.5^\circ$ Dec$\sim -26.4^\circ$, $\sim$50.9 degrees from the CMB dipole Apex. The signal to noise ratio (S/N) of the multiple $\Omega_\Lambda$ measurements in these directions is $3.2\lesssim $ S/N $\lesssim 8.4$. The first asymmetry is puzzling, and would indicate a systematic effect related with the distribution of Pantheon+ SNe on the sky and, probably, how the correction for reddening in the Galaxy is calculated. The second one, which entails a 2.8-$\sigma$ tension between $\Omega_\Lambda$ measure in opposite directions, bears strong implications on its interpretation as Dark Energy: It is consistent with the prediction for tilted observers located in a Friedmann-Robertson-Walker universe who could measure an acceleration or a deceleration with a dipolar asymmetry, irrespective of what the universe as a whole is doing. In this case, $\Omega_\Lambda$ would not be a physical entity, a real Dark Energy, but an apparent effect associated with the relativistic frame of reference transformation.