Coloquio IFIS para iniciar el último mes del año. Este 4 de diciembre, Alejandro Clocchiatti de la Pontificia Universidad Católica de Chile presenta “Global Anisotropies of ΩΛ” desde las 11:00 AM en la Sala 208 del Instituto de Física PUCV.
Te dejamos el abstract del coloquio:
An analysis of the cosmological parameter ΩΛ fitted to subsamples of the Pantheon+ Type Ia supernova sample spanning 2π steradians 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 toward R.A. ∼ 217fdg5, decl. ∼ −26fdg4, ∼50fdg9 from the cosmic microwave background dipole Apex. The signal-to-noise ratio (S/N) of the multiple ΩΛ measurements in these directions is 3.2 ≲ S/N ≲ 8.4. The first asymmetry is puzzling and would indicate a systematic effect related with the distribution of Pantheon+ supernovae on the sky and, probably, how the correction for reddening in the Galaxy is calculated. The second one, which entails a 2.8-σ tension between ΩΛ measured in opposite directions, bears strong implications on our interpretation of ΩΛ 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, ΩΛ would not be a physical entity, a real dark energy, but an apparent effect associated with the relativistic frame of reference transformation.
