SALT2: using distant supernovae to improve the use   of type Ia 
supernovae as distance indicators

Guy, J.; Astier, P.; Baumont, S.; Hardin, D.; Pain, R.; Regnault, Nicolas; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Hook, I. M.; Howell, D. A.; Perrett, K.; Pritchet, C. J.; Rich, J.; Sullivan, M.; Antilogus, P.; Aubourg, É.; Bazin, G.; Bronder, J.; Filiol, M.; Palanque-Delabrouille, N.; Ripoche, P.; Ruhlmann-Kleider, V.

doi:10.1051/0004-6361:20066930

Cited by 814 publications

(951 citation statements)

References 49 publications

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“…Both effects are summarised in c, thus assuming the same colour-magnitude relation for the combination of colour variation and host reddening at low and at high redshift. SALT II (Guy et al 2007) is similar to SALT, but uses a different spectral template. s has been replaced by a new stretch parameter x 1 .…”

Section: Supernova Data and Resultsmentioning

confidence: 99%

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Constraints on anisotropic cosmic expansion from supernovae

Kalus

Schwarz

Seikel

et al. 2013

A&A

105

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Aims. We test the isotropy of the expansion of the Universe by estimating the hemispherical anisotropy of supernova type Ia (SN Ia) Hubble diagrams at low redshifts (z < 0.2). Methods. We compare the best fit Hubble diagrams in pairs of hemispheres and search for the maximal asymmetric orientation. For an isotropic Universe, we expect only a small asymmetry due to noise and the presence of nearby structures. This test does not depend on the assumed content of the Universe, the assumed model of gravity, or the spatial curvature of the Universe. The expectation for possible fluctuations due to large scale structure is evaluated for the Λ cold dark matter (ΛCDM) model and is compared to the supernova data from the Constitution set for four different light curve fitters, thus allowing a study of the systematic effects. Results. The expected order of magnitude of the hemispherical asymmetry of the Hubble expansion agrees with the observed one. The direction of the Hubble asymmetry is established at 95% confidence level (C.L.) using both, the MLCS2k2 and the SALT II light curve fitter. The highest expansion rate is found towards ( , b) ≈ (−35 • , −19 • ), which agrees with directions reported by other studies. Its amplitude is not in contradiction to expectations from the ΛCDM model. The measured Hubble anisotropy is ΔH/H ∼ 0.026. With 95% C.L. the expansion asymmetry is ΔH/H < 0.038.

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Section: Supernova Data and Resultsmentioning

confidence: 99%

“…SALT and SALT II use a colour parameter to get rid of dust (Guy et al 2005(Guy et al , 2007. We tested the asymmetries in the colour parameter in the same way as those in the shape parameter.…”

Section: Colour Asymmetrymentioning

confidence: 99%

Constraints on anisotropic cosmic expansion from supernovae

Kalus

Schwarz

Seikel

et al. 2013

A&A

105

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“…One of the main surprises in the first-year analysis of the SDSS-II Supernova Survey (Kessler et al, 2009) was the realization that the two main algorithms developed by other groups for global fitting of SN light curves and cosmological parameters -MLCS2k2 ) and SALT2 (Guy et al 2007) -initially gave statistically inconsistent cosmological results (w = −0.76 ± 0.07 vs. w = −0.96 ± 0.06, quoting only the statistical errors) when applied to the same data sets, a discrepancy that persisted even if the SDSS-II data themselves were omitted from the fits. Kessler et al (2009) traced this discrepancy to two factors, one related to calibration data and the other to the treatment of SN colors.…”

Section: The Current State Of Playmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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“…The Union2.1 compilation is an updated version of Union2 [35] compilation by adding new SNe data from the Hubble Space Telescope Cluster Survey to Union2 compilation. All 580 SNe of Union2.1 were fit using the light curve fitter SALT2 [36]. The SALT2 fitter fits all SNe Ia with three parameters.…”

Section: Samplesmentioning

confidence: 99%

Constraining smoothness parameter and the DD relation of Dyer-Roeder equation with supernovae

Yang¹,

Yu²,

Zhang

2013

J. Cosmol. Astropart. Phys.

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Abstract. Our real universe is locally inhomogeneous. Dyer and Roeder introduced the smoothness parameter α to describe the influence of local inhomogeneity on angular diameter distance, and they obtained the angular diameter distance-redshift approximate relation (Dyer-Roeder equation) for locally inhomogeneous universe. Furthermore, the DistanceDuality (DD) relation, D L (z)(1 + z) −2 /D A (z) = 1, should be valid for all cosmological models that are described by Riemannian geometry, where D L and D A are, respectively, the luminosity and angular distance distances. Therefore, it is necessary to test whether if the Dyer-Roeder approximate equation can satisfy the Distance-Duality relation. In this paper, we use Union2.1 SNe Ia data to constrain the smoothness parameter α and test whether the Dyer-Roeder equation satisfies the DD relation. By using χ 2 minimization, we get α = 0.92 +0.08 −0.32 at 1σ and 0.92 +0.08 −0.65 at 2σ, and our results show that the Dyer-Roeder equation is in good consistency with the DD relation at 1σ.

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SALT2: using distant supernovae to improve the use of type Ia supernovae as distance indicators

Cited by 814 publications

References 49 publications

Constraints on anisotropic cosmic expansion from supernovae

Constraints on anisotropic cosmic expansion from supernovae

Observational probes of cosmic acceleration

Constraining smoothness parameter and the DD relation of Dyer-Roeder equation with supernovae

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