Project 14:
Stress testing the dark energy equation of state imprint on supernova data
This work determines the degree to which a standard Lambda-CDM analysis based on type Ia supernovae can identify deviations from a cosmological constant in the form of a redshift-dependent dark energy equation of state w(z).
We introduce and apply a novel random curve generator to simulate instances of w(z) from constraint families with increasing distinction from a cosmological constant. After producing a series of mock catalogs of binned type Ia supernovae corresponding to each w(z) curve, we perform a standard Lambda-CDM analysis to estimate the corresponding posterior densities of the absolute B-band magnitude of type Ia supernovae, the present-day matter density, and the equation of state parameter.
Using the Kullback-Leibler divergence between posterior densities as a difference measure, we demonstrate that a standard type Ia supernova cosmology analysis has limited sensitivity to extensive redshift dependencies of the dark energy equation of state. In addition, we report that larger redshift-dependent departures from a cosmological constant do not necessarily manifest easier-detectable incompatibilities with the Lambda-CDM model.
Our results suggest that physics beyond the standard model may simply be hidden in plain sight.
Full citation: Moews et al., 2019, Physical Review D, Volume 99, Issue 12, id.123529
This project is a result from COIN Residence Program #5 – Chania, Greece/2018.
Pre-print – Bibtex – Random curve generator
Team:
Ben Moews, U. Edinburgh (UK)
Rafael S. de Souza, U. North Carolina (USA)
Emille E. O. Ishida, CNRS/UCA (France)
Alex I. Malz, New York U. (USA)
Caroline Heneka, Scuola Normale Superiore di Pisa (Italy)
Ricardo Vilalta, U. Houston (USA)
Joe Zuntz, U. Edinburgh (UK)

Distributions of statistical difference measures between the Lambda-CDM, hypothetical exotic universes and our own.