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J/A+A/500/L17       Spectral flux ratio of SN Ia                 (Bailey+, 2009)

Using spectral flux ratios to standardize SN Ia luminosities. Bailey S., Aldering G., Antilogus P., Aragon C., Baltay C., Bongard S., Buton C., Childress M., Chotard N., Copin Y., Gangler E., Loken S., Nugent P., Pain R., Pecontal E., Pereira R., Perlmutter S., Rabinowitz D., Rigaudier G., Runge K., Scalzo R., Smadja G., Swift H., Tao C., Thomas R.C., Wu C. <Astron. Astrophys. 500, L17 (2009)> =2009A&A...500L..17B
ADC_Keywords: Supernovae ; Spectrophotometry Keywords: stars: supernovae: general - cosmology: observations Abstract: We present a new method to standardize Type Ia supernova (SN Ia) luminosities to ~<0.13mag using flux ratios from a single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotometry of 58 SNe Ia, we performed an unbiased search for flux ratios that correlate with SN Ia luminosity. After developing the method and selecting the best ratios from a training sample, we verified the results on a separate validation sample and with data from the literature. We identified multiple flux ratios whose correlations with luminosity are stronger than those of light curve shape and color, previously identified spectral feature ratios, or equivalent width measurements. In particular, the flux ratio R(642/443)=Flux(642nm)/Flux(443nm) has a correlation of 0.95 with SN Ia absolute magnitudes. Using this single ratio as a correction factor produces a Hubble diagram with a residual scatter standard deviation of 0.125±0.011mag, compared with 0.161±0.015mag when fit with the SALT2 light curve shape and color parameters x1 and c. The ratio R(642/443) is an effective correction factor for both extrinsic dust reddening and intrinsic variations such as those of SN 1991T-like and SN 1999aa-like SNe. When combined with broad-band color measurements, spectral flux ratios can standardize SN Ia magnitudes to ∼0.12mag. These are the first spectral metrics that give robust improvements over the standard normalization methods based upon light curve shape and color, and they provide among the lowest scatter Hubble diagrams ever published. Description: These tables provide the names, redshifts, lightcurve fit parameters, and measured flux ratios for the SNe. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 88 11 Flux Ratio correlations and Hubble residual stdev table2.dat 130 74 *SALT2 fit and R(642/443) flux ratios table3.dat 203 58 All flux ratios R, Rc for SNfactory SNe
Note on table2.dat: SALT2 parameters x1 and c and the decolored flux ratio Rc(642/443) were not measured or used for the literature SNe in this analysis, thus they are not included in this table.
See also: B/sn : Asiago Supernova Catalogue (Barbon et al., 1999-) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 11 A11 --- FitParms Hubble fit standardization parameters 14- 17 F4.2 --- rho.T Correlations in Training set 20- 23 F4.2 --- rho.V Correlations in Validation set 26- 29 F4.2 --- rho.C Correlations in Combined set 31- 34 F4.1 --- Gamma ?=- Flux ratio fit slope 36- 38 F3.1 --- e_Gamma ?=- Flux ratio fit slope error 42- 46 F5.3 mag sig.T Hubble residuals stdev Training set 48- 52 F5.3 mag e_sig.T stdev errors Training set 56- 60 F5.3 mag sig.V Hubble residuals stdev Validation set 62- 66 F5.3 mag e_sig.V stdev errors Validation set 70- 74 F5.3 mag sig.C Hubble residuals stdev Combined set 76- 80 F5.3 mag e_sig.C stdev errors Combined set 84- 88 F5.3 mag sigma Normalized Median Absolute Deviation
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Name SN Name 17 A1 --- Set [TVL] T=Training, V=Validation, L=Literature 19- 24 F6.4 --- zcmb Redshift in CMB frame 27- 31 F5.2 --- x1 ?=- SALT2 x1 light curve shape parameter 34- 37 F4.2 --- e_x1 ?=- SALT2 x1 parameter error 39- 44 F6.3 mag color ?=- SALT2 color parameter [∼E(B-V)] 46- 50 F5.3 mag e_color ?=- SALT2 color parameter error 52- 57 F6.3 mag dmuB Uncorrected Hubble diagram residual 59- 63 F5.3 mag e_dmuB Hubble diagram residual error 66- 70 F5.3 --- R642/443 Flux ratio R(642/443) 73- 77 F5.3 --- e_R642/443 Flux ratio R(642/443) error 80- 84 F5.3 --- Rc642/443 ?=- Decolored Flux ratio Rc(642/443) 87- 91 F5.3 --- e_Rc642/443 ?=- Decolored Flux ratio Rc(642/443) error 93-130 A38 --- Ref Non-SNfactory discovery reference
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Name SN Name 17 A1 --- Set [TV] T=Training, V=Validation 19- 24 F6.4 --- zcmb Redshift in CMB frame (1) 27- 31 F5.2 --- x1 SALT2 x1 light curve shape parameter 34- 37 F4.2 --- e_x1 SALT2 x1 parameter error 39- 44 F6.3 mag color SALT2 color parameter ∼E(B-V) 46- 50 F5.3 mag e_color SALT2 color parameter error 52- 57 F6.3 mag dmuB Uncorrected Hubble diagram residual 59- 63 F5.3 mag e_dmuB Hubble diagram residual error 66- 70 F5.3 --- R642/443 Flux ratio R(642/443) 73- 77 F5.3 --- e_R642/443 Flux ratio R(642/443) error 80- 84 F5.3 --- R642/417 Flux ratio R(642/417) 87- 91 F5.3 --- e_R642/417 Flux ratio R(642/417) error 94- 98 F5.3 --- R772/437 Flux ratio R(772/437) 101-105 F5.3 --- e_R772/437 Flux ratio R(772/437) error 108-112 F5.3 --- R642/512 Flux ratio R(642/512) 115-119 F5.3 --- e_R642/512 Flux ratio R(642/512) error 122-126 F5.3 --- R728/398 Flux ratio R(728/398) 129-133 F5.3 --- e_R728/398 Flux ratio R(728/398) error 136-140 F5.3 --- Rc642/519 Decolored Flux ratio Rc(642/519) 143-147 F5.3 --- e_Rc642/519 Decolored Flux ratio Rc(642/519) error 150-154 F5.3 --- Rc577/642 Decolored Flux ratio Rc(577/642) 157-161 F5.3 --- e_Rc577/642 Decolored Flux ratio Rc(577/642) error 164-168 F5.3 --- Rc642/536 Decolored Flux ratio Rc(642/536) 171-175 F5.3 --- e_Rc642/536 Decolored Flux ratio Rc(642/536) error 178-182 F5.3 --- Rc676/642 Decolored Flux ratio Rc(676/642) 185-189 F5.3 --- e_Rc676/642 Decolored Flux ratio Rc(676/642) error 192-196 F5.3 --- Rc642/443 Decolored Flux ratio Rc(642/443) 199-203 F5.3 --- e_Rc642/443 Decolored Flux ratio Rc(642/443) error
Note (1): Reference for non-SNfactory redshifts are from: de Vaucouleurs et al., RC3, Cat. VII/155 Keel, 1996, Cat. J/ApJS/106/27 Mathewson & Ford, 1996, Cat. J/ApJS/107/97 Theureau et al., 1998, Cat. J/A+AS/130/333 Huchra et al., 1999, Cat. J/ApJS/121/287 Falco et al., 1999, Cat. J/PASP/111/438 Koribalski et al., 2004, Cat. J/AJ/128/16 O'Neil, 2004, Cat. J/AJ/128/2080 Jones et al., 6dF, 2005i, Cat. VII/249 SDSS Data Release 7
Acknowledgements: Stephen Bailey, stephen.bailey(at)in2p3.fr
(End) Stephen Bailey [LPNHE Paris], Patricia Vannier [CDS] 02-Jul-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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