We search for possible deviations from the expectations of the concordance ΛCDM model in the expansion history of the Universe by analysing the Pantheon Type Ia Supernovae (SnIa) compilation along with its Monte Carlo simulations using redshift binning. We demonstrate that the redshift binned best fit ΛCDM matter density parameter Ω0m and the best fit effective absolute magnitude M oscillate about their full dataset best fit values with considerably large amplitudes. Using the full covariance matrix of the data taking into account systematic and statistical errors, we show that at the redshifts below z≈0.5 such oscillations can only occur in 4 to 5% of the Monte Carlo simulations. While statistical fluctuations can be responsible for this apparent oscillation, we might have observed a hint for some behaviour beyond the expectations of the concordance model or a possible additional systematic in the data. If this apparent oscillation is not due to statistical or systematic effects, it could be due to either the presence of coherent inhomogeneities at low z or due to oscillations of a quintessence scalar field.
If you use any of the above codes or the figures in a published work please cite the following paper:
Hints for Possible Low Redshift Oscillation Around the Best-Fitting ΛCDM Model in the Expansion History of the Universe
Lavrentios Kazantzidis, Hanwool Koo, Savvas Nesseris, Leandros Perivolaropoulos, Arman Shafieloo
Mon.Not.Roy.Astron.Soc. 501 (2021) 3, 3421, arxiv:2010.03491.
Any further questions/comments are welcome.
Lavrentios Kazantzidis - firstname.lastname@example.org
Hanwool Koo - email@example.com
Savvas Nesseris - firstname.lastname@example.org
Leandros Perivolaropoulos - email@example.com
Arman Shafieloo - firstname.lastname@example.org