J/ApJ/699/L139 Spectral parameters of SNe Ia (Wang+, 2009)
Improved distances to type Ia supernovae with two spectroscopic subclasses.
Wang X., Filippenko A.V., Ganeshalingam M., Li W., Silverman J.M., Wang L.,
Chornock R., Foley R.J., Gates E.L., Macomber B., Serduke F.J.D.,
Steele T.N., Wong D.S.
<Astrophys. J., 699, L139-L143 (2009)>
=2009ApJ...699L.139W 2009ApJ...699L.139W
ADC_Keywords: Supernovae ; Magnitudes
Keywords: cosmology: observations - distance scale - dust, extinction -
supernovae: general
Abstract:
We study the observables of 158 relatively normal Type Ia supernovae
(SNe Ia) by dividing them into two groups in terms of the expansion
velocity inferred from the absorption minimum of the SiIIλ6355
line in their spectra near B-band maximum brightness. One group
("Normal") consists of normal SNe Ia populating a narrow strip in the
SiII velocity distribution, with an average expansion velocity
<ν≥10600±400km/s near B maximum; the other group ("HV") consists
of objects with higher velocities, ν≳11800km/s. Compared with the
Normal group, the HV one shows a narrower distribution in both the
peak luminosity and the luminosity decline rate Δm15. In
particular, their B-V colors at maximum brightness are found to be on
average redder by ∼0.1mag, suggesting that they either are associated
with dusty environments or have intrinsically red B-V colors. The HV
SNe Ia are also found to prefer a lower extinction ratio RV∼1.6
(versus ∼2.4 for the Normal ones). Applying such an
absorption-correction dichotomy to SNe Ia of these two groups
remarkably reduces the dispersion in their peak luminosity from
0.178mag to only 0.125mag.
Description:
Spectral data for the 158 SNe Ia sample are primarily from Matheson et
al. (2008, Cat. J/AJ/135/1598) and our own database (J. M. Silverman
et al. 2009, in prep; 2011AAS...21732405S). For a few objects, the
spectral parameters were also taken from Benetti et al.
2005ApJ...623.1011B 2005ApJ...623.1011B, Branch et al. (2009PASP..121..238B 2009PASP..121..238B), and the IAU
Circulars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 158 Observed parameters of the SN Ia sample
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See also:
B/sn : Asiago Supernova Catalogue (Barbon et al., 1999-)
J/ApJ/607/665 : Type Ia supernovae at z>1 discovered by HST (Riess+, 2004)
J/ApJ/645/488 : SN type Ia luminosities (Wang+, 2006)
J/ApJ/659/122 : Improved distances to type Ia supernovae (Jha+, 2007)
J/MNRAS/389/1871 : Type Ia supernovae candidates from SDSS (Horesh+, 2008)
J/ApJ/673/981 : Type Ia supernova rates with HST ACS (Kuznetsova+, 2008)
J/AJ/135/1598 : Optical spectroscopy of type Ia supernovae (Matheson+, 2008)
J/A+A/477/717 : Spectroscopy of Type Ia supernovae (Bronder+, 2008)
J/AJ/136/2306 : SDSS-II SN survey, 2005 (Holtzman+, 2008)
J/A+A/500/L17 : Spectral flux ratio of SN Ia (Bailey+, 2009)
J/A+A/507/85 : ESO/VLT 3rd year type Ia supernova data set (Balland+, 2009)
J/MNRAS/406/782 : Type Ia supernovae luminosities (Sullivan+, 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- SN Supernova identification (YYYYaa)
8 A1 --- f_SN [d] SN-Ia with Cepheid distance
10- 14 I5 km/s cz Recession velocity (2)
16- 21 F6.2 mag VMAG Absolute V band magnitude at maximum
23- 26 F4.2 mag e_VMAG The 1σ uncertainty in VMAG
28- 31 F4.2 mag Dm15 Luminosity decline rate Δm15 (3)
33- 36 F4.2 mag e_Dm15 The 1σ uncertainty in Delm15
38- 42 F5.2 mag B-V The (B-V) color index at maximum
44- 47 F4.2 mag e_B-V The 1σ uncertainty in B-V
49- 53 F5.2 mag E(B-V) Host galaxy (B-V) color excess
55- 58 F4.2 mag e_E(B-V) Uncertainty in E(B-V)
60- 64 F5.1 --- TType ? RC3 host galaxy T morphology
65 A1 --- f_TType [?] Uncertainty flag on Morph
67- 68 A2 --- Type SN type ("HV" or "N" for normal) (4)
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Note (2): Distances to the SNe are computed by using the redshifts of their
host galaxies, in the reference frame of the 3K cosmic microwave
background radiation for samples at redshift z≳0.01 or corrected
to a self-consistent Virgocentric infall of 220km/s for closer ones,
with a Hubble constant H0=70.5 km/s/Mpc (Komatsu et al.
2009ApJS..180..330K 2009ApJS..180..330K). A peculiar-velocity component of 300km/s is
included in the distance-modulus uncertainties. Cepheid distances
are adopted whenever available (see Wang X. et al. 2006, Cat.
J/ApJ/645/488 and references therein).
Note (3): Value has been corrected for the reddening effect
(Phillips et al. 1999AJ....118.1766P 1999AJ....118.1766P).
Note (4): SN Ia sample is divided into "Normal" and "HV" groups according
to the observed velocity of SiIIλ6355.
N = "Normal" group which consists of normal SNe Ia populating a narrow strip
in the SiII velocity distribution, with an average expansion velocity
<ν≥10600±400km/s near B maximum;
HV = the other group which consists of objects with higher velocities,
ν≳11800km/s.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-Jul-2011