SIMBAD references

2023MNRAS.520.5110P - Mon. Not. R. Astron. Soc., 520, 5110-5125 (2023/April-3)

On the homogeneity of SnIa absolute magnitude in the Pantheon+ sample.

PERIVOLAROPOULOS L. and SKARA F.

Abstract (from CDS):

We have analysed the Pantheon+ sample using a new likelihood model that replaces the single Type Ia supernovae (SnIa) absolute magnitude parameter M used in the standard likelihood model of Brout et. al. with two absolute magnitude parameters (M< and M>) and a transition distance (dcrit) that determines the distance at which M changes from M< to M>. The use of this likelihood dramatically changes the quality of fit to the Pantheon+ sample for a Lambda cold dark matter background by Δχ2 = -19.6. The tension between the M< and M> best-fitting values is at a level more than 3σ with a best-fitting dcrit very close to $20\, \mathrm{Mpc}$. The origin of this improvement of fit and M<-M> tension is that the new likelihood model successfully models two signals hidden in the data: (1) the volumetric redshift scatter bias systematic and (2) a mild signal for a change of intrinsic SnIa luminosity at about $20\, \mathrm{Mpc}$. This interpretation of the results is confirmed by truncating the z < 0.01 Hubble diagram data from the Pantheon+ data where the above systematic is dominant and showing that the M<-M> tension decreases from above 3σ to a little less than 2σ. It is also confirmed by performing a Monte Carlo simulation, which shows that the maximum significance of the SnIa luminosity transition ($\Sigma \equiv \frac{|M_{\gt} -M_{\lt} |}{\sqrt{\sigma _{M_{\gt} }^2+\sigma _{M_{\lt} }^2}}$) as obtained from the real SH0ES data is larger than the corresponding maximum significance of $94{{\ \rm per\ cent}}$ of the corresponding homogeneous simulated samples.

Abstract Copyright: © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society

Journal keyword(s): cosmological parameters - dark energy - cosmology: distance scale - cosmology: observations - stars: supernovae general

Simbad objects: 37

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