2026/07/21 by Saibal Ray, Maxim Khlopov, Aritra Sanyal +2
#astro-ph.CO #gr-qc
We perform four independent decompositions of the deceleration parameter q0 using 1564 Type Ia supernovae (SNe Ia) from the Pantheon+ catalogue: by redshift bin, sky hemisphere, host galaxy mass, and supernova colour. Without any progenitor age correction, the full sample yields qm = - 0.062 -- far below the ΛCDM expectation of - 0.55 -- challenging the standard picture before any correction. Crucially, the sky hemisphere test shows the deceleration is equally strong in the CMB dipole (qm = + 1.45) and anti-dipole hemispheres (+ 1.55), directly contradicting the SRS26 anisotropy argument. Our results challenge both current interpretations.