J/ApJ/869/167 Improved empirical models for Type Ia SNe (Saunders+, 2018)
SNEMO: Improved empirical models for Type Ia supernovae.
Saunders C., Aldering G., Antilogus P., Bailey S., Baltay C., Barbary K.,
Baugh D., Boone K., Bongard S., Buton C., Chen J., Chotard N., Copin Y.,
Dixon S., Fagrelius P., Fakhouri H.K., Feindt U., Fouchez D., Gangler E.,
Hayden B., Hillebrandt W., Kim A.G., Kowalski M., Kusters D., Leget P.-F.,
Lombardo S., Nordin J., Pain R., Pecontal E., Pereira R., Perlmutter S.,
Rabinowitz D., Rigault M., Rubin D., Runge K., Smadja G., Sofiatti C.,
Suzuki N., Tao C., Taubenberger S., Thomas R.C., Vincenzi M.,
(the Nearby Supernova Factory)
<Astrophys. J., 869, 167-167 (2018)>
=2018ApJ...869..167S 2018ApJ...869..167S (SIMBAD/NED BibCode)
ADC_Keywords: Models ; Supernovae ; Spectroscopy
Keywords: cosmology: observations - supernovae: general
Abstract:
SN Ia cosmology depends on the ability to fit and standardize
observations of supernova magnitudes with an empirical model. We
present here a series of new models of SN Ia spectral time series that
capture a greater amount of supernova diversity than is possible with
the models that are currently customary. These are entitled SuperNova
Empirical MOdels (SNEMO; https://snfactory.lbl.gov/snemo). The models
are constructed using spectrophotometric time series from 172
individual supernovae from the Nearby Supernova Factory, comprising
more than 2000 spectra. Using the available observations, Gaussian
processes are used to predict a full spectral time series for each
supernova. A matrix is constructed from the spectral time series of
all the supernovae, and Expectation Maximization Factor Analysis is
used to calculate the principal components of the data. K-fold
cross-validation then determines the selection of model parameters and
accounts for color variation in the data. Based on this process, the
final models are trained on supernovae that have been dereddened using
the Fitzpatrick and Massa extinction relation. Three final models are
presented here: SNEMO2, a two-component model for comparison with
current Type Ia models; SNEMO7, a seven-component model chosen for
standardizing supernova magnitudes, which results in a total
dispersion of 0.100mag for a validation set of supernovae, of which
0.087mag is unexplained (a total dispersion of 0.113mag with an
unexplained dispersion of 0.097mag is found for the total set of
training and validation supernovae); and SNEMO15, a comprehensive
15-component model that maximizes the amount of spectral time-series
behavior captured.
Description:
Model spectra.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 671 8352 Training and Validation Set Model Parameters
list.dat 39 2474 *List of spectra
sp/* . 2474 Individual spectra
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Note on list.dat: Telescope UH88, Redshift=0.0.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 25 E25.18 d Phase [-10/46] SN phase
27- 50 E24.18 0.1nm lambda Wavelength (Angstroems)
52- 75 E24.18 --- SNEMO2c0 The SNEMO2c0 parameter
77-101 E25.18 --- SNEMO2c1 The SNEMO2c1 parameter
103-126 E24.18 --- SNEMO7c0 The SNEMO7c0 parameter
128-152 E25.18 --- SNEMO7c1 The SNEMO7c1 parameter
154-178 E25.18 --- SNEMO7c2 The SNEMO7c2 parameter
180-204 E25.18 --- SNEMO7c3 The SNEMO7c3 parameter
206-230 E25.18 --- SNEMO7c4 The SNEMO7c4 parameter
232-256 E25.18 --- SNEMO7c5 The SNEMO7c5 parameter
258-282 E25.18 --- SNEMO7c6 The SNEMO7c6 parameter
284-307 E24.18 --- SNEMO15c0 The SNEMO15c0 parameter
309-333 E25.18 --- SNEMO15c1 The SNEMO15c1 parameter
335-359 E25.18 --- SNEMO15c2 The SNEMO15c2 parameter
361-385 E25.18 --- SNEMO15c3 The SNEMO15c3 parameter
387-411 E25.18 --- SNEMO15c4 The SNEMO15c4 parameter
413-437 E25.18 --- SNEMO15c5 The SNEMO15c5 parameter
439-463 E25.18 --- SNEMO15c6 The SNEMO15c6 parameter
465-489 E25.18 --- SNEMO15c7 The SNEMO15c7 parameter
491-515 E25.18 --- SNEMO15c8 The SNEMO15c8 parameter
517-541 E25.18 --- SNEMO15c9 The SNEMO15c9 parameter
543-567 E25.18 --- SNEMO15c10 The SNEMO15c10 parameter
569-593 E25.18 --- SNEMO15c11 The SNEMO15c11 parameter
595-619 E25.18 --- SNEMO15c12 The SNEMO15c12 parameter
621-645 E25.18 --- SNEMO15c13 The SNEMO15c13 parameter
647-671 E25.18 --- SNEMO15c14 The SNEMO15c14 parameter
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Model name
13- 19 F7.3 --- Phase Phase
22- 39 A18 --- FileName Name of the spectrum file in subdirectory sp
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Byte-by-byte Description of file (#): sp/*
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Bytes Format Units Label Explanations
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1- 6 F6.1 0.1nm lambda Wavelength (Angstroems)
8- 30 E23.18 W/m2/nm Flux Flux (erg/s/cm2/Å * random offset)
32- 54 E23.19 W/m2/nm e_Flux rms uncertainty of Flux
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Acknowledgements:
Clare Saunders, cmsaunders(at)berkeley.edu
(End) Patricia Vannier [CDS] 03-Apr-2020