Improving Dark Energy Constraints with High Redshift Type Ia Supernovae from CANDELS and CLASH

TL;DR

Extending high-redshift Type Ia Supernova samples with HST data can significantly improve constraints on dark energy parameters, especially the evolution parameter wa, and enable tests for luminosity evolution with redshift.

Contribution

This study demonstrates how adding high-redshift SN Ia data from HST enhances dark energy parameter constraints and proposes future JWST surveys for luminosity evolution tests.

Findings

Up to 21% reduction in uncertainty of wa with additional high-z SNe

Up to 28% improvement in the figure of merit (FoM)

Feasibility of testing SN Ia luminosity evolution with JWST

Abstract

Aims. We investigate the degree of improvement in dark energy constraints that can be achieved by extending Type Ia Supernova (SN Ia) samples to redshifts z > 1.5 with the Hubble Space Telescope (HST), particularly in the ongoing CANDELS and CLASH multi-cycle treasury programs. Methods. Using the popular CPL parametrization of the dark energy, w = w0 +wa(1-a), we generate mock SN Ia samples that can be projected out to higher redshifts. The synthetic datasets thus generated are fitted to the CPL model, and we evaluate the improvement that a high-z sample can add in terms of ameliorating the statistical and systematic uncertainties on cosmological parameters. Results. In an optimistic but still very achievable scenario, we find that extending the HST sample beyond CANDELS+CLASH to reach a total of 28 SN Ia at z > 1.0 could improve the uncertainty in the wa parameter by up to 21%. The corresponding improvement in the figure of merit (FoM) would be as high as 28%. Finally, we consider the use of high-redshift SN Ia samples to detect non-cosmological evolution in SN Ia luminosities with redshift, finding that such tests could be undertaken by future spacebased infrared surveys using the James Webb Space Telescope (JWST).