THEHUBBLE SPACE TELESCOPECLUSTER SUPERNOVA SURVEY. V. IMPROVING THE DARK-ENERGY CONSTRAINTS ABOVEz> 1 AND BUILDING AN EARLY-TYPE-HOSTED SUPERNOVA SAMPLE
Обзор сверхновых в скоплениях с помощью космического телескопа «Хаббл». V. Улучшение ограничений на тёмную энергию при z > 1 и формирование выборки сверхновых в галактиках раннего типа
2012-01-27
SCID: 54.1/x9ye8uda
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Hubble Space TelescopeType Ia supernovaedark-energy constraintshigh-redshift supernovaeΛCDM cosmology
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Abstract (AI)
We present Advanced Camera for Surveys, NICMOS, and Keck adaptive-optics-assisted photometry of 20 Type Ia supernovae (SNe Ia) from the Hubble Space Telescope ( HST ) Cluster Supernova Survey. The SNe Ia were discovered over the redshift interval 0.623 < z < 1.415. Of these SNe Ia, 14 pass our strict selection cuts and are used in combination with the world's sample of SNe Ia to derive the best current constraints on dark energy. Of our new SNe Ia, 10 are beyond redshift z = 1, thereby nearly doubling the statistical weight of HST -discovered SNe Ia beyond this redshift. Our detailed analysis corrects for the recently identified correlation between SN Ia luminosity and host galaxy mass and corrects the NICMOS zero point at the count rates appropriate for very distant SNe Ia. Adding these SNe improves the best combined constraint on dark-energy density, ρ DE ( z ), at redshifts 1.0 < z < 1.6 by 18% (including systematic errors). For a flat ΛCDM universe, we find Ω Λ = 0.729 ± 0.014 (68% confidence level (CL) including systematic errors). For a flat w CDM model, we measure a constant dark-energy equation-of-state parameter w = −1.013 +0.068 −0.073 (68% CL). Curvature is constrained to ∼0.7% in the ow CDM model and to ∼2% in a model in which dark energy is allowed to vary with parameters w 0 and w a . Further tightening the constraints on the time evolution of dark energy will require several improvements, including high-quality multi-passband photometry of a sample of several dozen z > 1 SNe Ia. We describe how such a sample could be efficiently obtained by targeting cluster fields with WFC3 on board HST . The updated supernova Union2.1 compilation of 580 SNe is available at http://supernova.lbl.gov/Union .
Key Findings
1
Accounting for host-galaxy mass–luminosity correlations and NICMOS count-rate-dependent zero-point calibration improved the analysis; the dark-energy-density constraint at 1.0 < z < 1.6 improved by 18%, including systematic errors.
2
For flat ΛCDM, ΩΛ = 0.729 ± 0.014, while flat wCDM gives w = −1.013 +0.068 −0.073; curvature is constrained to approximately 0.7% or 2%, depending on the model.
3
Fourteen supernovae passed strict selection criteria and were combined with the global Type Ia supernova sample to constrain dark energy.
4
Further constraints on dark-energy evolution require multi-passband photometry of several dozen z > 1 Type Ia supernovae, efficiently obtainable by targeting cluster fields with HST WFC3.
5
Photometry of 20 Type Ia supernovae spanning 0.623 < z < 1.415 was obtained from the Hubble Space Telescope Cluster Supernova Survey.
6
Ten newly discovered supernovae lie beyond z = 1, nearly doubling the statistical weight of Hubble-discovered supernovae at these redshifts.
Research Object
Type Ia supernovae at redshifts 0.623 < z < 1.415, including those hosted by early-type galaxies
Research Subject
Their luminosity and redshift-dependent constraints on the dark-energy density and equation of state, including host-galaxy-mass effects
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2012-01-27
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