J/A+A/614/A71 SNF20080514-002 and LSQ12fxd spectra (Nordin+, 2018)
Understanding Type Ia supernovae through their U-band spectra.
Nordin J., Aldering G., Antilogus P., Aragon C., Bailey S., Baltay C.,
Barbary K., Bongard S., Boone K., Brinnel V., Buton C., Childress M.,
Chotard N., Copin Y., Dixon S., Fagrelius P., Feindt U., Fouchez D.,
Gangler E., Hayden B., Hillebrandt W., Kim A., Kowalski M., Kuesters D.,
Leget P.-F., Lombardo S., Lin Q., Pain R., Pecontal E., Pereira R.,
Perlmutter S., Rabinowitz D., Rigault M., Runge K., Rubin D., Saunders C.,
Smadja G., Sofiatti C., Suzuki N., Taubenberger S., Tao C., Thomas R.C.
(The Nearby Supernova Factory)
<Astron. Astrophys. 614, A71 (2018)>
=2018A&A...614A..71N 2018A&A...614A..71N (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Spectroscopy
Keywords: supernovae: general - cosmology - dark energy
Abstract:
Observations of Type Ia supernovae (SNe Ia) can be used to derive
accurate cosmological distances through empirical standardization
techniques. Despite this success neither the progenitors of SNe Ia nor
the explosion process are fully understood. The U-band region has been
less well observed for nearby SNe, due to technical challenges, but is
the most readily accessible band for high-redshift SNe.
Using spectrophotometry from the Nearby Supernova Factory, we study
the origin and extent of U-band spectroscopic variations in SNe Ia and
explore consequences for their standardization and the potential for
providing new insights into the explosion process.
We divide the U-band spectrum into four wavelength regions
λ(uNi), λ(uTi), λ(uSi) and λ(uCa). Two of
these span the Ca H&K λλ3934,3969 complex. We employ
spectral synthesis using SYNAPPS to associate the two bluer regions
with Ni/Co and Ti.
Results: (1) The flux of the uTi feature is an extremely sensitive
temperature/luminosity indicator, standardizing the SN peak luminosity
to 0.116±0.011mag RMS. A traditional SALT2.4 fit on the same sample
yields a 0.135mag RMS. Standardization using uTi also reduces the
difference in corrected magnitude between SNe originating from
different host galaxy environments. (2) Early U-band spectra can be
used to probe the Ni+Co distribution in the ejecta, thus offering a
rare window into the source of lightcurve power. (3) The uCa flux
further improves standardization, yielding a 0.086±0.010mag RMS
without the need to include an additional intrinsic dispersion to
reach chi2/dof∼1. This reduction in RMS is partially driven by an
improved standardization of Shallow Silicon and 91T-like SNe.
Description:
Data release of the Nearby Supernova Factory spectra of
SNF20080514-002 and LSQ12fxd, from SNfactory Data Releases
(https://snfactory.lbl.gov/snf/data/)
Objects:
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RA (2000) DE Designation(s)
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13 29 12.84 +11 16 20.5 SNF20080514-002 = SNF20080514-002
05 22 16.99 -25 35 47.0 LSQ12fxd = LSQ 12fxd
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 48 4 List of spectra
sp/* . 4 Individual spectra
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See also:
https://snfactory.lbl.gov/snf/data : SNfactory Data Releases
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name SN name
17- 22 F6.2 d Phase Phase of observation (1)
24- 48 A25 --- FileName Name of the file in subdirectory sp (2)
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Note (1): phase of observation, in days relative to the DayMax parameter of the
SALT lightcurve fitter (Guy et al. 2007A&A...466...11G 2007A&A...466...11G,
2010, Cat. J/A+A/523/A7), times 100:
Note (2): Each spectrum has been corrected for Milky Way dust extinction, with
the reddening E(B-V)_MW derived from the dust maps of Schlafly & Finkbeiner
(2011ApJ...737..103S 2011ApJ...737..103S). The Milky Way reddening corrections assume the
extinction curve model of Fitzpatrick (1999PASP..111...63F 1999PASP..111...63F) with RV=3.1.
The spectra have also been de-redshifted to the rest frame.
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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- 24 E24.19 0.1nm lambda Wavelength
26- 49 E24.19 --- Flux Flux
51- 74 E24.19 --- Var Variance (photon noise)
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History:
Copied at https://snfactory.lbl.gov/snf/data/
(End) Patricia Vannier [CDS] 13-Jun-2018