Type Ia Supernova Distances at Redshift >1.5 from the Hubble Space Telescope Multi-cycle Treasury Programs: The Early Expansion Rate

Abstract

We present an analysis of 15 Type Ia supernovae (SNe Ia) at redshift > z 1 (9 at < < z 1.5 2.3) recently discovered in the CANDELS and CLASH Multi-Cycle Treasury programs using WFC3 on the Hubble Space Telescope. We combine these SNeIa with a new compilation of ∼1050 SNeIa, jointly calibrated and corrected for simulated survey biases to produce accurate distance measurements. We present unbiased constraints on the expansion rate at six redshifts in the range < < z 0.07 1.5 based only on this combined SNIa sample. The added leverage of our new sample at > z 1.5 leads to a factor of ∼3 improvement in the determination of the expansion rate at z=1.5, reducing its uncertainty to ∼20%, a measurement of2.69 0 0.52 0.86 . We then demonstrate that these six derived expansion rate measurements alone provide a nearly identical characterization of dark energy as the full SN sample, making them an efficient compression of the SNIa data. The new sample of SNeIa at > z 1.5 usefully distinguishes between alternative cosmological models and unmodeled evolution of the SNIa distance indicators, placing empirical limits on the latter. Finally, employing a realistic simulation of a potential Wide-Field Infrared Survey Telescope SN survey observing strategy, we forecast optimistic future constraints on the expansion rate from SNeIa.

Measuring Dark Energy Properties with Photometrically Classified Pan-STARRS Supernovae. II. Cosmological Parameters

“…Evidence for β evolution was seen in SNLS data , though its significance is attributed to selection effects in B14. S17 found just 1σ evidence for β evolution (β = (3.139 ± 0.099)+z×(−0.348 ± 0.289)), a measurement that includes SNe at redshifts up to ∼2 (Riess et al 2018). Though there are not enough SNe Ia at z>1.5 to constrain a changing value of β, larger high-z data sets may be able to confirm or discount β evolution.…”

First cosmology results using type Ia supernovae from the Dark Energy Survey: the effect of host galaxy properties on supernova luminosity

“…In this paper, we also consider other SN Ia samples from the literature: the JLA sample (Betoule et al 2014) (740 SNe Ia) and the 'Pantheon' sample (Scolnic et al 2018). The latter combines SNe Ia discovered by the Pan-STARRS1 (PS1) Medium Deep Survey with the JLA sample, as well as events from the Hubble Space Telescope (Suzuki et al 2012;Riess et al 2018) to form a sample of 1048 SNe Ia.…”

“…As standardisable candles, type Ia supernovae (SNe Ia) are a geometric probe of the expansion history of the universe (Riess et al 1998;Perlmutter et al 1999) and provide a mature, robust measure of its accelerated expansion (Betoule et al 2014;Riess et al 2018;Scolnic et al 2018;DES Collaboration 2019). SNe Ia are not perfect standard candles: empirical 'corrections' based on light-curve shape (Phillips 1993) and colour (Riess et al 1996;Tripp 1998) are required to standardise their peak luminosity, reducing the observed scatter in their peak magnitudes from ∼0.35 mag to ∼0.14 mag, or ∼ 7 per cent in distance.…”

Distinguishing freezing and thawing dark energy models through measurements of the fine-structure constant

“…Below, we constrain this class of models using a combination of cosmological and astrophysical observations complemented by local tests. For background cosmology, we use the recent Pantheon catalogue of Type Ia supernovas of Riess et al (2018), including its covariance matrix, together with the compilation of 38 measurements of the Hubble parameter by Farooq et al (2017). The latter is important for extending the redshift lever arm and extending the overlap with the range of redshifts of α measurements.…”