J/A+A/614/A134 SNe Ia spectra from SNLS (Balland+, 2018)
The ESO's VLT type Ia supernova spectral set of the final two years of SNLS.
Balland C., Cellier-Holzem F., Lidman C., Astier P., Betoule M.,
Carlberg R.G., Conley A., Ellis R.S., Guy J., Hardin D., Hook I.M.,
Howell D.A., Pain R., Pritchet C.J., Regnault N., Sullivan M.,
Arsenijevic V., Baumont S., El-Hage P., Fabbro S., Fouchez D., Mitra A.,
Moeller A., Mourao A.M., Neveu J., Roman M., Ruhlmann-Kleider V.
<Astron. Astrophys. 614, A134 (2018)>
=2018A&A...614A.134B 2018A&A...614A.134B (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Supernovae ; Spectra, optical ; Spectral types
Keywords: cosmology: observations - supernovae: general -
methods: data analysis - techniques: spectroscopic
Abstract:
We aim to present 70 spectra of 68 new high-redshift type Ia
supernovae (SNe Ia) measured at ESO's VLT during the final two years
of operation (2006-2008) of the Supernova Legacy Survey (SNLS). This
new sample complements the VLT three year spectral set. Altogether,
these two data sets form the five year sample of SNLS SN Ia spectra
measured at the VLT on which the final SNLS cosmological analysis will
partly be based. In the redshift range considered, this sample is
unique in terms of homogeneity and number of spectra. We use it to
investigate the possibility of a spectral evolution of SNe Ia
populations with redshift as well as SNe Ia spectral properties as a
function of lightcurve fit parameters and the mass of the host-galaxy.
Reduction and extraction are based on both IRAF standard tasks and our
own reduction pipeline. Redshifts are estimated from host-galaxy lines
whenever possible or alternatively from supernova features. We used
the spectro-photometric SN Ia model SALT2 combined with a set of
galaxy templates that model the host-galaxy contamination to assess
the type Ia nature of the candidates.
We identify 68 new SNe Ia with redshift ranging from z=0.207 to z=0.98
for an average redshift of z=0.62. Each spectrum is presented
individually along with its best-fit SALT2 model. Adding this new
sample to the three year VLT sample of SNLS, the final dataset
contains 209 spectra corresponding to 192 SNe Ia identified at the
VLT. We also publish the redshifts of other candidates (host galaxies
or other transients) whose spectra were obtained at the same time as
the spectra of live SNe Ia. This list provides a new redshift catalog
useful for upcoming galaxy surveys. Using the full VLT SNe Ia sample,
we build composite spectra around maximum light with cuts in color,
the lightcurve shape parameter ("stretch"), host-galaxy mass and
redshift. We find that high-z SNe Ia are bluer, brighter and have
weaker intermediate mass element absorption lines than their low-z
counterparts at a level consistent with what is expected from
selection effects. We also find a flux excess in the range
[3000-3400]Å for SNe Ia in low mass host-galaxies
(M<1010M☉) or with locally blue U-V colors, and suggest that
the UV flux (or local color) may be used in future cosmological
studies as a third standardization parameter in addition to stretch
and color.
Description:
The SNLS experiment benefited from exceptional spectroscopic surveys,
with a total of ∼1500 hours of observation on 8-10m class telescopes,
including the VLT with two ESO large programs. Special attention was
paid to assessing the type and determining the redshift of the SN Ia
candidates using a combination of SALT2 and visual inspection.
This release contains:
1: a catalog of all the non SNIa objects measured in Multi Object
Spectroscopy (MOS) mode during the SNLS survey
2: the SNeIa spectra observed at the Very Large Telescope (VLT) from
August 1st, 2006 up to the end of the SuperNova Legacy Survey (SNLS)
mid-2008. To this set, we add 8 SNeIa spectra that were acquired in
MOS mode before August 1st, 2006 but that were not included in the
3-year SNLS VLT spectral sample as the extraction pipeline used for
that analysis did not support MOS mode (those are SN 05D1dx, SN
05D1hm, SN 05D1if, SN 05D2le, SN 06D2ag, SN 06D4ba, SN 06D4bo and SN
06D4bw). For completeness, we further add the spectrum of SN 06D2bo, a
Type Ia supernova measured in Long Slit Spectroscopy (LSS) mode in
February 2006 that was initially misclassified as a non-SNIa object.
In total, 70 spectra of 68 SNeIa identified as SNeIa are presented.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 69 70 Observing log of the VLT SNe Ia of the last
two years of SNLS
tablea2.dat 78 70 Spectral properties of the VLT SNe Ia of the
last two years of SNLS
tablea3.dat 69 1349 Catalog of redshifts and identifications of the
non-SN Ia objects measured in MOS mode at the
VLT during the SNLS survey
sp/* . 70 Individual spectra
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See also:
http://supernovae.in2p3.fr/Snls5VltRelease : Snls5Vlt Home Page
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name SNLS SN name
8- 10 A3 --- n_Name Note on Name (1)
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 22 F5.2 s RAs Right ascension (J2000)
24 A1 --- DE- Declination sign (J2000)
25- 26 I2 deg DEd Declination (J2000)
28- 29 I2 arcmin DEm Declination (J2000)
31- 34 F4.1 arcsec DEs Declination (J2000)
36- 45 A10 "date" Obs.date Spectrum observation date (UTC)
47- 51 A5 s ExpTime Exposure time
53- 56 F4.2 arcsec Seeing ?=- Seeing
57 A1 --- n_Seeing [f] f: Seeing not available for this object
59- 62 F4.2 --- Airmass Air mass
64- 68 F5.2 mag imag Magnitude at observation time (iM)
69 A1 --- n_imag [e] e: Value obtained from online logs
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Note (1): Notes as follows:
a = Spectrum measured in MOS mode during the first three years of SNLS.
The SN is included in the SNLS three-year sample of Guy et al.
(2010, Cat. J/A+A/523/A7) but the spectrum is not in the VLT three-year
spectral set of Balland et al. (2009, Cat J/A+A/507/85).
b = Spectrum taken in LSS mode
c = Observed with Grism 300I and order sorting filter OG590
d = Identified as a SN Ia by Bazin et al. (2011A&A...534A..43B 2011A&A...534A..43B) after a new
extraction
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name SNLS SN name
8- 15 A8 -- Type SN type (1)
18- 22 F5.3 --- z Redshfit, not corrected to the heliocentric
reference frame, computed in 5Å bins
24- 28 F5.3 --- e_z rms uncertainty on z
30 A1 --- r_z [HS] Source of x
32- 35 F4.1 --- phi Phase
37- 45 A9 --- ModelH Host model
47- 50 F4.2 --- FracH Host fraction
52- 55 F4.1 --- <S/N> Mean signal-to-noise ratio,
computed in 5Å bins
57- 78 A22 --- FileName Name of the spectrum file in subdirectory sp
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Note (1): SNIa* for the candidate is likely a SN Ia but other types cannot be
excluded given the S/N and phase. The spectra that fall into this category do
not present clear SN Ia features. They typically have a low S/N and/or a phase
larger than +5days and/or heavy host-galaxy contamination.
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name SNLS SN name (when relevant)
9- 10 I2 h RAh Right ascension (J2000)
12- 13 I2 min RAm Right ascension (J2000)
15- 19 F5.2 s RAs Right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Declination (J2000)
25- 26 I2 arcmin DEm Declination (J2000)
28- 31 F4.1 arcsec DEs Declination (J2000)
33- 37 F5.3 --- z Redshift
38 A1 --- n_z [*] * for redshift obtained from a single
identified line
40- 69 A30 --- ID Identification (1)
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Note (1): We use the ID column to distinguish between host galaxies that were
targeted after the transient had faded from view, live transients (using the
labels SNIbc, SNII, SNII? or ?), and random field galaxies.
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Byte-by-byte Description of file (#): sp/*
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Bytes Format Units Label Explanations
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3- 6 I4 --- Xpix Index of wavelength bin
12- 19 F8.3 0.1nm lambda Wavelength
31- 40 F10.7 10-18W/m2/nm Flux Flux (10-16erg/s/cm2/Å) (1)
47- 55 F9.7 10-18W/m2/nm e_Flux rms uncertainty on Flux
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Note (1): en 10-18 erg/cm2/s/AA juste snonly06D1ez1389.dat
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Acknowledgements:
Christophe Balland, balland(at)lpnhe.in2p3.fr
References:
Balland et al., 2009A&A...507...85B 2009A&A...507...85B
(End) C. Balland [Sorbonne Univ., LPNHE, France], P. Vannier [CDS] 29-Jun-2018