2011A&A...526A..81B


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.03CEST23:05:28

2011A&A...526A..81B - Astronomy and Astrophysics, volume 526A, 81-81 (2011/2-1)

Do spectra improve distance measurements of type Ia supernovae?

BLONDIN S., MANDEL K.S. and KIRSHNER R.P.

Abstract (from CDS):

We investigate the use of a wide variety of spectroscopic measurements to determine distances to low-redshift Type Ia supernovae (SN Ia) in the Hubble flow observed through the CfA Supernova Program. We consider linear models for predicting distances to SN Ia using light-curve width and color parameters (determined using the SALT2 light-curve fitter) and a spectroscopic indicator, and evaluate the resulting Hubble diagram scatter using a cross-validation procedure. We confirm the ability of spectral flux ratios alone at maximum light to reduce the scatter of Hubble residuals by ∼10% [weighted rms, or WRMS=0.189±0.026mag for the flux ratio R(6630/4400)] with respect to the standard combination of light-curve width and color, for which WRMS=0.204±0.029mag. When used in combination with the SALT2 color parameter, the color-corrected flux ratio Rc(6420/5290) at maximum light leads to an even lower scatter (WRMS=0.175±0.025mag), although the improvement has low statistical significance (<2σ) given the size of our sample (26 SN Ia). We highlight the importance of an accurate relative flux calibration and the failure of this method for highly-reddened objects. Comparison with synthetic spectra from 2D delayed-detonation explosion models shows that the correlation of R(6630/4400) with SN Ia absolute magnitudes can be largely attributed to intrinsic color variations and not to reddening by dust in the host galaxy. We consider flux ratios at other ages, as well as the use of pairs of flux ratios, revealing the presence of small-scale intrinsic spectroscopic variations in the iron-group-dominated absorption features around ∼4300Å and ∼4800Å. The best flux ratio overall is the color-corrected Rc(4610/4260) at t=-2.5d from maximum light, which leads to ∼30% lower scatter (WRMS=0.143±0.020mag) with respect to the standard combination of light-curve width and color, at ∼2σ significance. We examine other spectroscopic indicators related to line-profile morphology (absorption velocity, pseudo-equivalent width etc.), but none appear to lead to a significant improvement over the standard light-curve width and color parameters. We discuss the use of spectra in measuring more precise distances to SN Ia and the implications for future surveys which seek to determine the properties of dark energy.

Abstract Copyright:

Journal keyword(s): supernovae: general - cosmology: observations

Simbad objects: 31

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Number of rows : 31

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 SN 2006sr SN* 00 03 35.02 +23 11 46.2     17.4     SNIa 36 1
2 SN 2003it SN* 00 05 48.47 +27 27 09.6     17.2     SNIa 26 1
3 SN 2000dk SN* 01 07 23.52 +32 24 23.2   15.63 15.2     SNIa 84 1
4 SN 2002jy SN* 01 21 16.27 +40 29 55.3     16.3     SNIa 30 1
5 SN 2001eh SN* 01 38 12.10 +41 39 18.8     16.5     SNIa 45 1
6 SN 2002hu SN* 02 18 20.06 +37 27 58.8   16.83       SNIa 39 1
7 SN 2003iv SN* 02 50 07.25 +12 50 46.5     17.2     SNIa 27 1
8 SN 2006gj SN* 03 17 35.80 -01 41 30.2     17.8     SNIa 37 1
9 SN 1999ek SN* 05 36 31.60 +16 38 17.8   17.97       SNIa 52 1
10 SN 2002kf SN* 06 37 15.31 +49 51 10.2     15.9     SNIa 20 1
11 SN 2000fa SN* 07 15 29.88 +23 25 42.4   15.85       SNIa 66 1
12 SN 2003ch SN* 07 17 57.92 +09 41 34.9     17.4     SNIa 24 1
13 SN 1995E SN* 07 51 56.75 +73 00 34.6   16.81 15.9     SNIa 106 1
14 SN 1999aa SN* 08 27 42.03 +21 29 14.8           SNIap 229 1
15 SN 1999gd SN* 08 38 24.61 +25 45 33.1   16.94       SNIa 60 1
16 SN 2002hd SN* 08 54 04.69 -07 10 59.8     18     SNIa 23 1
17 SN 2005ki SN* 10 40 28.355 +09 10 57.14     18.0     SNIa 68 1
18 SN 1998bu SN* 10 46 46.01 +11 50 07.5   12.11       SNIa 296 1
19 SN 2006ax SN* 11 24 03.46 -12 17 29.2     17.1     SNIa 73 1
20 SN 2004as SN* 11 25 39.18 +22 49 49.4     17.3     SNIa 37 1
21 SN 2008bf SN* 12 04 02.90 +20 14 42.6           SNIa 44 2
22 SN 2006X SN* 12 22 53.93 +15 48 32.0     15.3     SNIa 280 1
23 SN 1999cl SN* 12 31 56.01 +14 25 35.3   14.92       SNIa 107 1
24 SN 2006br SN* 13 30 01.80 +13 24 56.8     17.8     SNIa 33 1
25 SN 2007ca SN* 13 31 05.81 -15 06 06.6     16.7     SNIa 47 1
26 SN 2002ck SN* 15 47 00.75 -00 59 25.5     16.8     SNIa 35 1
27 SN 1999cc SN* 16 02 42.03 +37 21 34.4   16.78       SNIa 62 1
28 SN 2003U SN* 17 22 45.66 +62 09 50.4     18.0     SNIa 35 1
29 SN 1998dx SN* 18 11 11.89 +49 51 40.7   17.71       SNIa 39 1
30 SN 1998V SN* 18 22 37.40 +15 42 08.4   15.07       SNIa 59 1
31 SN 1998eg SN* 22 39 30.29 +08 36 20.6   16.11       SNIa 51 1

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2020.07.03-23:05:28

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