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The High-Z and SNLS surveys (1998–2005) transformed dark energy from theoretical speculation into observational fact, using increasingly large and precise high-redshift Type Ia supernova samples to measure luminosity distances and constrain the cosmological constant and equation of state. This program produced the evidence-standard for cosmic acceleration and enabled systematic constraints on w.
14 papers, in the order the idea moved · each quote is the paper’s own definition, and each is marked to say whether we found it word for word in the paper (verified), could not find it (inferred), or have not re-checked it against the paper’s text as it now stands
The paper measured the cosmological constant energy density (an early proxy for dark energy) from the magnitude-redshift relation of high-redshift supernovae.
“we find Ω_ M = 0.94 ^+0.34_-0.28 or, equivalently, a measurement of the cosmological constant, Ω_Λ = 0.06 ^+0.28_-0.34 (<0.51 at the 95% confidence level).”◌ not checked against the paper’s text as it now stands
It presented a joint confidence region on the Ω_M–Ω_Λ plane for general Friedmann-Lemaître cosmologies, which is the theoretical framework in which a cosmological-constant-like dark energy component is parameterized.
“For the more general Friedmann-Lemaître cosmologies with independent Ω_ M and Ω_Λ, the results are presented as a confidence region on the Ω_ M–Ω_Λ plane.”◌ not checked against the paper’s text as it now stands
The paper's results argued against a low-density, Λ-dominated flat universe model that had been proposed to reconcile globular cluster ages with high Hubble constant values.
“The results for Ω_Λ-versus-Ω_ M are inconsistent with Λ-dominated, low density, flat cosmologies that have been proposed to reconcile the ages of globular cluster stars with higher Hubble constant values.”◌ not checked against the paper’s text as it now stands
The paper noted that future supernova data spanning a wider redshift range could separately measure Ω_M and Ω_Λ, laying groundwork for later dark energy measurements.
“This change in slope with redshift makes possible a future measurement of both Ω_ M and Ω_Λ separately, using supernovae at a range of redshifts from z=0.5 to 1.0; see Figure 1 of Goobar & Perlmutter.”◌ not checked against the paper’s text as it now stands
“Within Friedmann-Lemaître cosmological models, the apparent bolometric magnitude m(z) of a standard candle (absolute bolometric magnitude M) at a given redshift is a function of both the cosmological-constant energy density Ω_Λ≡Λ/(3H_0^2) and the mass density Ω_ M:”✓ verified · Measurements of the Cosmological Paramet…, 1996
The paper uses high-redshift Type Ia supernova distances to place constraints on the matter density and cosmological constant, finding evidence that matter alone cannot produce a flat universe.
“The redshift-distance relation is used to place constraints on the global mean matter density, Ω_m, and the normalized cosmological constant, Ω_Λ. When the HST sample is combined with the distance to SN 1995K (z=0.48), analyzed by the same precepts, it suggests that matter alone is insufficient to produce a flat Universe.”◌ not checked against the paper’s text as it now stands
They derive a best estimate for the matter density assuming zero cosmological constant, showing a low Ω_m consistent with a nonzero dark energy component in a flat universe.
“Specifically, for Ω_m+Ω_Λ =1, Ω_m is less than 1 with >95% confidence, and our best estimate of Ω_m is -0.1 ± 0.5 if Ω_Λ =0.”◌ not checked against the paper’s text as it now stands
The paper finds that if the universe is flat, a cosmological constant must make a substantial contribution to the energy density, implying evidence for dark energy.
“The indication from our data is that the matter density is low; as shown in Figure 3, either the Universe is open, or if flat, then a cosmological constant makes a considerable contribution (which may be in conflict with limits from gravitational lensing statistics (Kochanek 1996)).”
The paper derived a constraint on the cosmological constant density parameter Ω_Λ by combining a high-redshift supernova with a nearby sample under the assumption of a flat universe.
“For a spatially flat universe composed of normal matter and a cosmological constant, we find Ω_M = 0.4^+0.5_-0.4, Ω_Λ = 0.6^+0.4_-0.5.”◌ not checked against the paper’s text as it now stands
The paper explicitly incorporated a cosmological constant term (Ω_Λ) into the theoretical framework for luminosity distance as a function of redshift.
“We adopt a conventional model in which the matter content of the Universe is composed of a sum of components each having a fraction Ω_i of the current critical density ρ_crit≡ 3H_0^2/8π G and various equations of state with density ρ_i∝ ( volume)^-(1+α_i) [e.g., α=0 for normal matter (Ω_M), α=-1 for a cosmological constant (Ω_Λ), α=+1/3 for radiation (Ω_ rad), α=-1/3 for non-commuting strings (Ω_ S)].”◌ not checked against the paper’s text as it now stands
The paper showed that observations spanning a range of redshifts could distinguish flat universes with non-zero cosmological constant from open universes containing only normal matter.
“In particular, it is possible to separate flat cosmological models with non-zero Ω_Λ from open universes containing only normal matter (Goobar and Perlmutter 1995).”
The paper presents observational evidence from Type Ia supernovae that the universe's expansion is accelerating, implying the existence of a dark energy component.
“Different light curve fitting methods, SN Ia subsamples, and prior constraints unanimously favor eternally expanding models with positive cosmological constant (i.e., Ω_Λ > 0) and a current acceleration of the expansion (i.e., q_0 < 0).”◌ not checked against the paper’s text as it now stands
The paper places statistically significant quantitative constraints on the vacuum energy density (cosmological constant) using supernova data.
“With no prior constraint on mass density other than Ω_M ≥ 0, the spectroscopically confirmed SNe Ia are statistically consistent with q_0 <0 at the 2.8σ and 3.9σ confidence levels, and with Ω_Λ >0 at the 3.0σ and 4.0σ confidence levels, for two different fitting methods respectively.”◌ not checked against the paper’s text as it now stands
The paper rules out a matter-dominated universe with zero cosmological constant, supporting the need for a dark energy component.
“Presently, none of these effects reconciles the data with Ω_Λ=0 and q_0 ≥ 0.”◌ not checked against the paper’s text as it now stands
The paper measured the cosmological-constant energy density (a proxy for dark energy) alongside the mass density using 42 high-redshift Type Ia supernovae.
“We report measurements of the mass density, Ω_ M, and cosmological-constant energy density, Ω_Λ, of the universe based on the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology Project.”◌ not checked against the paper’s text as it now stands
It found that the data are strongly inconsistent with a zero-cosmological-constant flat universe, disfavoring the simplest inflationary model without dark energy.
“The data are strongly inconsistent with a Λ = 0 flat cosmology, the simplest inflationary universe model.”◌ not checked against the paper’s text as it now stands
The study provided statistical evidence that the cosmological constant (dark energy) is non-zero and positive, at 99% confidence.
“the data indicate that the cosmological constant is non-zero and positive, with a confidence of P(Λ > 0) = 99%, including the identified systematic uncertainties.”◌ not checked against the paper’s text as it now stands
For a flat universe, the paper derived a best-fit mass density that implies a substantial dark-energy component making up the rest of the energy density.
The paper presents an independent set of eleven high-redshift supernovae observed with HST to confirm previous supernova evidence for dark energy/cosmic acceleration.
“We report measurements of Ω_M, Ω_Λ, and w from eleven supernovae at z=0.36–0.86 with high-quality lightcurves measured using WFPC2 on the HST. This is an independent set of high-redshift supernovae that confirms previous supernova evidence for an accelerating Universe.”◌ not checked against the paper’s text as it now stands
The paper derives a measurement of the dark energy equation of state parameter w by combining the new supernova data with CMB and galaxy redshift distortion measurements.
“When the supernova results are combined with independent flat-universe measurements of Ω_M from CMB and galaxy redshift distortion data, they provide a measurement of w=-1.05^+0.15_-0.20 (statistical) ±0.09 (identified systematic), if w is assumed to be constant in time.”◌ not checked against the paper’s text as it now stands
The paper strengthens the statistical case for the existence of dark energy by directly correcting for host-galaxy extinction on an individual supernova basis rather than relying on assumed priors.
“Our cosmological fits using full extinction corrections confirm that dark energy is required with P(Ω_Λ>0)>0.99, a result consistent with previous and current supernova analyses which rely upon the identification of a low-extinction subset or prior assumptions concerning the intrinsic extinction distribution.”
The paper presents new high-redshift SNe Ia data providing the first conclusive evidence for a transition from cosmic deceleration to the current acceleration attributed to dark energy.
“We have discovered 16 Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to provide the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration.”◌ not checked against the paper’s text as it now stands
The study places quantitative constraints on the static equation of state parameter w of dark energy by combining SN Ia data with CMB and large-scale structure constraints.
“When combined with external flat-Universe constraints including the cosmic microwave background and large-scale structure, we find w=-1.02 ± ^0.13_0.19 (and w<-0.76 at the 95% confidence level) for an assumed static equation of state of dark energy, P = wρ c^2.”◌ not checked against the paper’s text as it now stands
The paper provides joint constraints on both the current equation of state and its time evolution, substantially improving precision over previous estimates and testing for evolving dark energy.
“Joint constraints on both the recent equation of state of dark energy, w_0, and its time evolution, dw/dz, are a factor of ∼ 8 more precise than its first estimate and twice as precise as those without the SNe Ia discovered with HST.”
The paper measures cosmological parameters relevant to dark energy, including the matter density and the dark energy equation of state parameter w, from a new supernova sample.
“Cosmological fits to this first year SNLS Hubble diagram give the following results: Ω_ M = 0.263 ± 0.042 (stat) ± 0.032 (sys) for a flat ΛCDM model; and w = -1.023 ± 0.090 (stat) ± 0.054 (sys) for a flat cosmology with constant equation of state w when combined with the constraint from the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations.”◌ not checked against the paper’s text as it now stands
The paper frames the discovery of cosmic acceleration and the introduction of dark energy as a major breakthrough motivating this survey.
“The discovery of the acceleration of the Universe stands as a major breakthrough of observational cosmology. Surveys of cosmologically distant Type Ia supernovae […] indicated the presence of a new, unaccounted-for “dark energy” that opposes the self-attraction of matter and causes the expansion of the Universe to accelerate.”◌ not checked against the paper’s text as it now stands
The paper discusses the theoretical significance of measuring w precisely to distinguish a cosmological constant from dynamical dark energy models.
“Measuring the average value of w with a precision better than 0.1 will permit a discrimination between the null hypothesis (pure cosmological constant, w=-1) and some dynamical dark energy models.”
The paper reports the discovery of 21 new HST-detected SNe Ia and a total sample of 23 z≥1 SNe Ia used to trace cosmic expansion history and characterize dark energy's early behavior.
“We have discovered 21 new Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to trace the history of cosmic expansion over the last 10 billion years.”◌ not checked against the paper’s text as it now stands
The study provides the first meaningful constraint on the dark energy equation-of-state parameter at z≥1, finding it consistent with a cosmological constant and ruling out rapidly evolving dark energy.
“The unique leverage of the HST high-redshift SNe Ia provides the first meaningful constraint on the dark energy equation-of-state parameter at z ≥ 1. The result remains consistent with a cosmological constant (w(z)=-1), and rules out rapidly evolving dark energy (dw /dz >>1).”◌ not checked against the paper’s text as it now stands
The paper shows evidence, at ~98% confidence, that dark energy's defining negative pressure was present even before the epoch of acceleration at z>1.
“The defining property of dark energy, its negative pressure, appears to be present at z>1, in the epoch preceding acceleration, with ∼ 98% confidence in our primary fit.”
The paper derives constraints on the dark energy equation-of-state parameter w using Type Ia supernovae from the ESSENCE survey combined with baryon acoustic oscillation data.
“By including constraints on (, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w= and = with a best-fit of.”◌ not checked against the paper’s text as it now stands
The paper combines ESSENCE results with the SuperNova Legacy Survey to produce a joint constraint on the dark energy equation of state and finds consistency with a cosmological constant.
“Combining our set of ESSENCE with the SuperNova Legacy Survey, we obtain a joint constraint of w=, =with a best-fit of. The current data are fully consistent with a cosmological constant.”◌ not checked against the paper’s text as it now stands
The paper evaluates systematic errors affecting supernova-based dark energy measurements, identifying host-galaxy dust extinction as the dominant current systematic.
“We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic currently with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies.”
The paper combines the CfA3 SN Ia sample with the Union set to create the Constitution set, deriving new dark energy equation of state constraints consistent with a cosmological constant.
“The CfA3 sample is added to the Union set of […] to form the Constitution set and, combined with a BAO prior, produces 1+w=0.013^+0.066_-0.068 (0.11 syst), consistent with the cosmological constant.”◌ not checked against the paper’s text as it now stands
The study identifies systematic uncertainties from multiple light curve fitters as now dominating over statistical uncertainties in dark energy measurements.
“The CfA3 addition makes the cosmologically-useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role.”◌ not checked against the paper’s text as it now stands
The paper tests for systematic differences in dark energy constraints using four different light curve fitters and finds specific biases in each.
“We use four light curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R_V=3.1), and MLCS2k2 (R_V=1.7). SALT produces high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < Δ < 1.2. MLCS2k2 with R_V=3.1 overestimates host-galaxy extinction while R_V≈1.7 does not.”
The paper compiled the Union2 dataset of 557 supernovae and used it to measure the dark energy equation of state parameter w, finding it consistent with a cosmological constant.
“We call this new compilation, consisting of 557 supernovae, the Union2compilation. The flat concordance ΛCDM model remains an excellent fit to the Union2data with the best fit constant equation of 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.”◌ not checked against the paper’s text as it now stands
The paper presents improved constraints on the redshift evolution of dark energy's equation of state, w(z), while noting no significant deviation from a constant w is detected.
“We also present improved constraints on w(z). While no significant change in w with redshift is detected, there is still considerable room for evolution in w.”◌ not checked against the paper’s text as it now stands
The paper points out that at the highest redshifts probed (z ≳ 1), current data only weakly constrain the existence and nature of dark energy.
“In particular, at z ≳ 1, the existence and nature of dark energy are only weakly constrained by the data.”
The paper uses SN Ia data alone to demonstrate that cosmic acceleration is required at extremely high confidence, even accounting for systematics.
“SN data alone require cosmic acceleration at >99.999 % confidence, including systematic effects.”◌ not checked against the paper’s text as it now stands
It derives a specific measurement of the dark energy equation-of-state parameter w from supernovae alone, consistent with a cosmological constant.
“For the dark energy equation of state parameter (assumed constant out to at least z=1.4) in a flat universe, we find w = -0.91^+0.16_-0.20( stat) ^+0.07_-0.14( sys) from SNe only, consistent with a cosmological constant.”◌ not checked against the paper’s text as it now stands
The survey's overarching aim is to measure the time-averaged equation of state of dark energy to specific precision goals.
“The goal of this survey is to measure the time averaged equation of state of dark energy w to 0.05 (statistical uncertainties only) in combination with other measurements, and to 0.10 including systematic effects.”◌ not checked against the paper’s text as it now stands
The paper uses new HST-discovered SNe Ia combined with the world's SN sample to derive improved constraints on dark energy, including the dark energy density and equation-of-state parameter.
“Fourteen of these pass our strict selection cuts and are used in combination with the world's sample of to derive the best current constraints on dark energy.”◌ not checked against the paper’s text as it now stands
The paper reports that adding these new supernovae improves the combined constraint on the dark energy density ρ_DE(z) at redshifts 1.0<z<1.6 by 18% including systematic errors.
“Adding these supernovae improves the best combined constraint on dark energy density, ρ_DE(z), at redshifts 1.0 < z < 1.6 by 18% (including systematic errors).”◌ not checked against the paper’s text as it now stands
The paper provides measurements of the constant dark energy equation-of-state parameter w in a flat wCDM model and constrains curvature in owCDM and w0-wa models.
“For a flat wCDM model, we measure a constant dark energy equation-of-state parameter (68% CL). Curvature is constrained to ∼ 0.7% in the owCDM model and to ∼ 2% in a model in which dark energy is allowed to vary with parameters w_0 and w_a.”
One thread of the map, each claim pinned to the paper’s own words. A chatbot gives you the canon; this carries the papers in between, in order, with the evidence attached.
The paper constructs confidence contours in the Ω_m–Ω_Λ plane from supernova data to visualize the allowed parameter space for the cosmological constant and matter density.
“Confidence contours in the Ω_m, Ω_Λ plane for the high-z SNe listed in Table 1 using the MLCS distances. The solid diagonal line represents the locus for a flat Universe.”◌ not checked against the paper’s text as it now stands
“The indication from our data is that the matter density is low; as shown in Figure 3, either the Universe is open, or if flat, then a cosmological constant makes a considerable contribution (which may be in conflict with limits from gravitational lensing statistics (Kochanek 1996)).”✓ verified · Constraints on Cosmological Models from …, 1997
The paper projected that a larger sample of ~30 high-redshift SN Ia would allow precise determination of Ω_M (and by extension constrain Ω_Λ) to an uncertainty of ±0.2.
“We demonstrate that with a sample of ∼ 30 objects, we should be able to determine relative luminosity distances over the range 0 < z< 0.5 with sufficient precision to measure Ω_M with an uncertainty of ± 0.2.”◌ not checked against the paper’s text as it now stands
“The CMB observations provide a nearly orthogonal set of parameters, so we will be able to separate the effects of any exotic forms of matter-energy in the Universe from normal matter.”✓ verified · The High‐Z Supernova Search: Measuring C…, 1998
The paper explicitly identifies the cosmological constant/vacuum energy as an exotic form of energy with negative pressure that could accelerate cosmic expansion.
“Pre-eminent among these is a possible energy of the vacuum (Ω_Λ), Einstein's “cosmological constant,” whose negative pressure would do work to accelerate the expansion (Carroll, Press, & Turner 1992; Schmidt et al. 1998).”◌ not checked against the paper’s text as it now stands
“Pre-eminent among these is a possible energy of the vacuum (Ω_Λ), Einstein's “cosmological constant,” whose negative pressure would do work to accelerate the expansion (Carroll, Press, & Turner 1992; Schmidt et al. 1998).”✓ verified · Observational Evidence from Supernovae f…, 1998
“For a flat (Ω_ M+Ω_Λ = 1) cosmology we find Ω_ M^ flat = 0.28^+0.09_-0.08 (1σ statistical) ^+0.05_-0.04 (identified systematics).”◌ not checked against the paper’s text as it now stands
“We report measurements of the mass density, Ω_ M, and cosmological-constant energy density, Ω_Λ, of the universe based on the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology Project.”✓ verified · Measurements of Ω and Λ from 42 High‐Red…, 1998
The paper argues that supernova observations remain the most direct evidence for dark energy compared to other cosmological probes, motivating the need for improved precision and systematic control.
“Although combinations of other measurements lead to a separate confirmation of the Universe's acceleration […], taken alone it is the supernovae that provide the best direct evidence for dark energy. Therefore, it is of importance to improve the precision of the supernova result, to confirm the result with additional independent high-redshift supernovae, and also to limit the possible effects of systematic errors.”◌ not checked against the paper’s text as it now stands
“These results ruled out a flat, matter-dominated (, ) universe. For a flat universe, motivated by inflation theory, these studies yielded a value for the cosmological constant of Ω_Λ≃0.7. Even in the absence of assumptions about the geometry of the Universe, the supernova measurements indicate the existence of dark energy with greater than 99% confidence.”✓ verified · New Constraints on Ω<sub><i>M</i></sub>,…, 2003
The results are shown to be consistent with a cosmological constant as the source of dark energy and inconsistent with rapid evolution of dark energy or astrophysical alternatives like dust or luminosity evolution.
“Our constraints are consistent with the static nature of and value of w expected for a cosmological constant (i.e., w_0 = -1.0, dw/dz = 0), and are inconsistent with very rapid evolution of dark energy.”◌ not checked against the paper’s text as it now stands
“Observations of type Ia supernovae (SNe Ia) at redshift z < 1 provide startling and puzzling evidence that the expansion of the Universe at the present time appears to be accelerating, behavior attributed to “dark energy” with negative pressure (Riess et al. 1998; Perlmutter et al. 1999; for reviews, see Riess 2000; Filippenko 2001, 2004; Leibundgut 2001).”✓ verified · Type Ia Supernova Discoveries at<i>z</i>…, 2004
The paper argues that a much larger supernova sample is needed to significantly improve constraints on dark energy beyond current results.
“Improving significantly over current SN constraints on the dark energy requires a ten-fold larger sample (i.e. o(1000) at 0.2<z<1., where w is best measured), in order to significantly improve on statistical errors but also, most importantly, on systematic uncertainties.”◌ not checked against the paper’s text as it now stands
“Surveys of cosmologically distant Type Ia supernovae […] indicated the presence of a new, unaccounted-for “dark energy” that opposes the self-attraction of matter and causes the expansion of the Universe to accelerate.”✓ verified · The Supernova Legacy Survey: measurement…, 2005
By measuring H(z) at discrete epochs with the new high-z sample, the paper strengthened evidence for the transition from deceleration to acceleration (cosmic jerk), a key signature used to infer dark energy's dominance.
“Combined with previous SN Ia datasets, we measured H(z) at discrete, uncorrelated epochs, reducing the uncertainty of H(z>1) from 50% to under 20%, strengthening the evidence for a cosmic jerk–the transition from deceleration in the past to acceleration in the present.”◌ not checked against the paper’s text as it now stands
“The accelerating cosmic expansion first inferred from observations of distant type Ia supernovae (SNe Ia; Riess et al. 1998; Perlmutter et al. 1999) indicates unexpected gravitational physics, frequently attributed to the dominating presence of a “dark energy” with negative pressure.”✓ verified · New<i>Hubble Space Telescope</i>Discover…, 2006
The ESSENCE program was designed specifically to measure the cosmic expansion history to test whether dark energy differs from a cosmological constant with a target precision of σ_w=0.1.
“The aim of ESSENCE is to measure the history of cosmic expansion over the past 5 billion years with sufficient precision to distinguish whether the dark energy is different from a cosmological constant at the σ_w=±0.1 level.”◌ not checked against the paper’s text as it now stands
“We present constraints on the dark energy equation-of-state parameter, w=P/(ρ c^2), using Type Ia supernovae from the ESSENCE supernova survey.”✓ verified · Observational Constraints on the Nature …, 2007
The paper explores host-galaxy dependent systematics relevant to dark energy inference, finding no evidence for a Hubble bubble but a population difference by host morphology.
“Our investigation is consistent with no Hubble bubble. We also find that, after light-curve correction, SN Ia in Scd/Sd/Irr hosts are intrinsically fainter than those in E/S0 hosts by 2σ, suggesting that they may come from different populations.”◌ not checked against the paper’s text as it now stands
“They have been the key element in the discovery that the universe is accelerating and dominated by dark energy […]. Observational efforts have moved beyond merely establishing the existence of dark energy and are focused on determining its simplest properties. This is most often done in terms of the equation of state, p = wρ, where the equation of state parameter, w, relates the dark energy density, ρ, to the dark energy pressure, p.”✓ verified · IMPROVED DARK ENERGY CONSTRAINTS FROM ∼1…, 2009
The paper emphasizes that increasing the sample of high-redshift SNe Ia is important for constraining astrophysical systematics that could otherwise mimic dark energy signatures in cosmological fits.
“An important role for SNe Iabeyond z ∼ 1, in addition to constraining the time evolution of w, is their power to constrain astrophysical effects that would systematically bias cosmological fits. Most evolutionary effects are expected to monotonically change with redshift and are not expected to mimic dark energy over the entire redshift interval over which SNe Ia can be observed.”◌ not checked against the paper’s text as it now stands
“In particular, at z ≳ 1, the existence and nature of dark energy are only weakly constrained by the data.”✓ verified · SPECTRA AND<i>HUBBLE SPACE TELESCOPE</i>…, 2010
The paper develops a detailed systematics covariance matrix methodology, improving on prior treatments of systematic uncertainties in dark energy constraints from supernovae.
“We pay particular attention to systematic uncertainties, characterizing them using a systematics covariance matrix that incorporates the redshift dependence of these effects, as well as the shape-luminosity and color-luminosity relationships. Unlike previous work, we include the effects of systematic terms on the empirical light-curve models.”◌ not checked against the paper’s text as it now stands
“The fundamental nature of dark energy, which makes up 3/4 of the mass-energy budget of the universe, remains almost completely mysterious. A solid measurement that w ≠ -1 (which would rule out the cosmological constant) would have profound implications for cosmology and particle physics.”✓ verified · SUPERNOVA CONSTRAINTS AND SYSTEMATIC UNC…, 2010
The paper discusses strategies, such as targeting cluster fields with WFC3 on HST, to obtain the larger high-redshift SNe Ia samples needed to further tighten constraints on the time evolution of dark energy.
“Tightening further 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. We describe how such a sample could be efficiently obtained by targeting cluster fields with WFC3 on HST.”◌ not checked against the paper’s text as it now stands
“Fourteen of these pass our strict selection cuts and are used in combination with the world's sample of to derive the best current constraints on dark energy.”✓ verified · THE<i>HUBBLE SPACE TELESCOPE</i>CLUSTER …, 2011