English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We report on work to increase the number of well-measured Type Ia supernovae(SNe Ia) at high redshifts. Light curves, including high signal-to-noise HSTdata, and spectra of six SNe Ia that were discovered during 2001 are presented.Additionally, for the two SNe with z>1, we present ground-based J-bandphotometry from Gemini and the VLT. These are among the most distant SNe Ia forwhich ground based near-IR observations have been obtained. We add these sixSNe Ia together with other data sets that have recently become available in theliterature to the Union compilation (Kowalski et al. 2008). We have made anumber of refinements to the Union analysis chain, the most important onesbeing the refitting of all light curves with the SALT2 fitter and an improvedhandling of systematic errors. We call this new compilation, consisting of 557supernovae, the Union2 compilation. The flat concordance LambdaCDM modelremains an excellent fit to the Union2 data with the best fit constant equationof state parameter w=-0.997^{+0.050}_{-0.054} (stat) ^{+0.077}_{-0.082}(stat+sys\ together) for a flat universe, or w=-1.035^{+0.055}_{-0.059}(stat)^{+0.093}_{-0.097} (stat+sys together) with curvature. We also presentimproved constraints on w(z). While no significant change in w with redshift isdetected, there is still considerable room for evolution in w. The strength ofthe constraints depend strongly on redshift. In particular, at z > 1, theexistence and nature of dark energy are only weakly constrained by the data.

Spectra and Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation