SiFTO: An Empirical Method for Fitting SN Ia Light Curves

By A. Conley, Mark Sullivan, E. Hsiao, J. Guy, P. Astier, D. Balam, C. Balland, S. Basa, R. Carlberg, D. Fouchez and 7 more. 2008

202 citations recorded by the source corpus.

We present SiFTO, a new empirical method for modeling Type Ia supernova (SN Ia) light curves by manipulating a spectral template. We make use of high-redshift SN data when training the model, allowing us to extend it bluer than rest-frame U. This increases the utility of our high-redshift SN observations by allowing us to use more of the available data. We find that when the shape of the light curve is described using a stretch prescription, applying the same stretch at all wavelengths is not an adequate description. SiFTO therefore uses a generalization of stretch which applies different stretch factors as a function of both the wavelength of the observed filter and the stretch in the rest-frame B band. We compare SiFTO to other published light-curve models by applying them to the same set of SN photometry, and demonstrate that SiFTO and SALT2 perform better than the alternatives when judged by the scatter around the best-fit luminosity distance relationship. We further demonstrate that when SiFTO and SALT2 are trained on the same data set the cosmological results agree.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/4688d499176cd1d9de1904bebe6575b977723b10

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In Astronomy and Astrophysics

1. A. Riess
2. A. Filippenko
3. R. Kirshner
4. S. Jha
5. D. Schneider
6. Daniel J. Eisenstein
7. S. Smartt
8. D. Weinberg

In Nuclear and High Energy Physics

1. R. Kirshner
2. S. Smartt
3. A. Filippenko
4. A. Riess
5. S. Jha
6. D. Weinberg
7. E. Berger
8. Weidong Li

Citations in the corpus

• Results from the Supernova Photometric Classification Challenge (2010, methodology): “— SN Ia identification used the sifto light-curve fitter (Conley et al. 2008) that was developed by the SNLS.”
• COSMOLOGICAL CONSTRAINTS FROM MEASUREMENTS OF TYPE Ia SUPERNOVAE DISCOVERED DURING THE FIRST 1.5 yr OF THE Pan-STARRS1 SURVEY (2013, background): “Since then, new approaches and new algorithms have improved lightcurve fitting so that well-observed SN Ia have individual luminosity distances good to 5% (e.g., MLCS2K2, Jha et al. 2007; Stretch, Goldhaber et al. 2001; SALT, Guy et al. 2007; SiFTO, Conley et al. (2008); and BayeSN, Mandel et al. 20”
• Fourteen months of observations of the possible super-Chandrasekhar mass Type Ia Supernova 2009dc (2010, methodology): “In addition, the conversion from stretch to m15 used by Maeda & Iwamoto (2009) for SN 2003fg did not take into account the fact that the definition of stretch has evolved as new SN Ia light-curve templates have been constructed (e.g. Conley et al. 2008).”
• CfA4: LIGHT CURVES FOR 94 TYPE Ia SUPERNOVAE (2012, background): “SALT2 (Guy et al. 2007) and SiFTO (Conley et al. 2008) are other popular light-curve fitters.”
• Observational probes of cosmic acceleration (2012, methodology): “SALT-style fitters (which include the SiFTO [Conley et al. 2008] algorithm applied to SNLS3) instead apply a global, simultaneous fit of parameters describing cosmology and the relationship between supernova light curves and absolute magnitude.”
• Type Ia Supernovae Are Good Standard Candles in the Near Infrared: Evidence from PAIRITEL (2007, methodology): “…1998; Jha et al. 2007), the ‘‘stretch’’ method (Perlmutter et al. 1997; Goldhaber et al. 2001), the color-magnitude intercept calibration method (CMAGIC;Wang et al. 2003), the spectral adaptive template method (SALT/SALT2; Guy et al. 2005, 2007; Astier et al. 2006), and SiFTO (Conley et al. 2008).”
• The dependence of Type Ia Supernovae luminosities on their host galaxies (2010, methodology): “These corrections are applied in different ways depending on whether a technique is a distance estimator (e.g., MLCS2k2; Jha et al. 2007) or a light curve fitter (e.g. SALT or SiFTO; Guy et al. 2007; Conley et al. 2008), though the underlying principle is the same in both approaches.”
• Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples (2014, methodology): “The estimate of model systematics in the C11 analysis was based on the comparison of light-curve parameters reconstructed from the same data by two different models (SALT2 and SiFTO, Conley et al. 2008).”
• The Supernova Legacy Survey 3-year sample: Type Ia supernovae photometric distances and cosmological constraints , (2010, methodology): “The two light curve fitting techniques used in this analysis, SiFTO (Conley et al. 2008) and SALT2 (Guy et al. 2007), are presented in§4.”
• Hubble Space Telescope spectra of the type Ia supernova SN 2011fe: a tail of low-density, high-velocity material with Z < Z⊙ (2013, methodology): “Here, we use the SiFTO light curve fitter (Conley et al. 2008) to fitg photometry from the P48 (as this provides the earliest photometric coverage) andBV R data published by Vinkó et al. (2012).”
• SNLS3: CONSTRAINTS ON DARK ENERGY COMBINING THE SUPERNOVA LEGACY SURVEY THREE-YEAR DATA WITH OTHER PROBES (2011, methodology): “0.06 SNe Ia for the training, and therefore cannot be supplemented with SNLS/SDSS SN data sampling the rest-frame U -band as is the case with SALT2 and SiFTO.”
• IMPROVED DARK ENERGY CONSTRAINTS FROM ∼100 NEW CfA SUPERNOVA TYPE Ia LIGHT CURVES (2009, background): “…candles and the most useful distance indicators at cosmological scales (e.g., Phillips 1993; Hamuy et al. 1996a; Riess, Press, & Kirshner 1996; Perlmutter et al. 1997; Jha et al. 1999; Goldhaber et al. 2001; Guy et al. 2005; Jha, Riess, & Kirshner 2007; Guy et al. 2007; Conley et al. 2008).”
• SUPERNOVA CONSTRAINTS AND SYSTEMATIC UNCERTAINTIES FROM THE FIRST THREE YEARS OF THE SUPERNOVA LEGACY SURVEY (2011, methodology): “Furthermore, SALT2 and SiFTO show small and opposite trends, with SiFTO increasing while SALT2 decreases.”
• SPECTRA AND HUBBLE SPACE TELESCOPE LIGHT CURVES OF SIX TYPE Ia SUPERNOVAE AT 0.511 < z < 1.12 AND THE UNION2 COMPILATION (2010, methodology): “We also find that β is higher for the redder SNe Ia which is similar to the results from Conley et al. (2008) based on comparisons of U − B colors to B − V , after correcting for the effect of stretch on the U - band.”
• TYPE Ia SUPERNOVA LIGHT CURVE INFERENCE: HIERARCHICAL MODELS IN THE OPTICAL AND NEAR-INFRARED (2010, background): “…include Δm15(B) (Phillips 1993; Hamuy et al. 1996b; Phillips et al. 1999; Prieto et al. 2006), multicolor light curve shapes (MLCS; Riess et al. 1996a, 1998; Jha et al. 2007), “stretch” (Goldhaber et al. 2001), CMAGIC (Wang et al. 2003), SALT (Guy et al. 2005, 2007), and SiFTO (Conley et al. 2008).”
• THE CARNEGIE SUPERNOVA PROJECT: LIGHT-CURVE FITTING WITH SNooPy (2010, background): “Presently, SALT2 (Guy et al. 2007) and SifTO (Conley et al. 2008) have joined the ranks of light-curve fitters and are capable of working in rest-frame i.”