Improved Cosmological Constraints from New, Old, and Combined Supernova Data Sets
Улучшенные космологические ограничения по новым, старым и объединённым наборам данных о сверхновых
2008-10-17
SCID: 54.1/9483ph4v
Discuss with AI
CMB and BAOType Ia supernovaeUnion compilationdark energy densityequation of state parameter
Figures from the paper
Abstract (AI)
We present a new compilation of Type Ia supernovae (SNe Ia), a new data set of low-redshift nearby-Hubble-flow SNe, and new analysis procedures to work with these heterogeneous compilations. This "Union" compilation of 414 SNe Ia, which reduces to 307 SNe after selection cuts, includes the recent large samples of SNe Ia from the Supernova Legacy Survey and ESSENCE Survey, the older data sets, as well as the recently extended data set of distant supernovae observed with the Hubble Space Telescope ( HST ). A single, consistent, and blind analysis procedure is used for all the various SN Ia subsamples, and a new procedure is implemented that consistently weights the heterogeneous data sets and rejects outliers. We present the latest results from this Union compilation and discuss the cosmological constraints from this new compilation and its combination with other cosmological measurements (CMB and BAO). The constraint we obtain from supernovae on the dark energy density is Ω Λ = 0.713 + 0.027 −0.029 (stat) + 0.036 −0.039 (sys) , for a flat, ΛCDM universe. Assuming a constant equation of state parameter, w , the combined constraints from SNe, BAO, and CMB give w = − 0.969 + 0.059 −0.063 (stat) + 0.063 −0.066 (sys) . While our results are consistent with a cosmological constant, we obtain only relatively weak constraints on a w that varies with redshift. In particular, the current SN data do not yet significantly constrain w at z > 1. With the addition of our new nearby Hubble-flow SNe Ia, these resulting cosmological constraints are currently the tightest available.
Key Findings
1
A single blind analysis and new weighting and outlier-rejection procedures consistently handle heterogeneous supernova subsamples.
2
Combining supernovae with BAO and CMB yields w = −0.969⁺⁰·⁰⁵⁹₋₀·⁰⁶³ (stat) ⁺⁰·⁰⁶³₋₀·⁰⁶⁶ (sys) for a constant dark-energy equation of state.
3
For a flat ΛCDM universe, supernovae constrain the dark-energy density to ΩΛ = 0.713⁺⁰·⁰²⁷₋₀·₀₂₉ (stat) ⁺⁰·⁰³⁶₋₀·⁰³⁹ (sys).
4
The Union compilation combines 414 Type Ia supernovae from new and historical surveys, retaining 307 objects after selection cuts.
5
The results are consistent with a cosmological constant, but current supernova data weakly constrain redshift-dependent w, especially at z > 1; adding nearby Hubble-flow supernovae provides the tightest constraints available at the time.
Research Object
Type Ia supernova observations and their Union compilation, including low- and high-redshift supernova samples
Research Subject
Cosmological constraints on dark-energy density and the equation-of-state parameter, including their redshift dependence, derived from supernova data and combined CMB and BAO measurements
Publication Details
Publication Date
2008-10-17
Journal
Publisher
ISSN
Open access PDF
Access Type
Author Information
Download PDF
Subscribe to digest