Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· Full Refereed Journal Article (PDF/Postscript)
· arXiv e-print (arXiv:1012.0005)
· References in the article
· Citations to the Article (24) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (31)
· NED Objects (52)
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Do spectra improve distance measurements of Type Ia supernovae?
Authors:
Blondin, S.; Mandel, K. S.; Kirshner, R. P.
Affiliation:
AA(Centre de Physique des Particules de Marseille (CPPM), CNRS/IN2P3, 163avenue de Luminy, 13288 Marseille Cedex 9, France ), AB(Harvard-Smithsonian Center for Astrophysics (CfA), 60 Garden Street, Cambridge, MA 02138, USA), AC(Harvard-Smithsonian Center for Astrophysics (CfA), 60 Garden Street, Cambridge, MA 02138, USA)
Publication:
Astronomy and Astrophysics, Volume 526, id.A81, 24 pp. (A&A Homepage)
Publication Date:
02/2011
Origin:
EDP Sciences
Astronomy Keywords:
supernovae: general, cosmology: observations
DOI:
10.1051/0004-6361/201015792
Bibliographic Code:
2011A&A...526A..81B

Abstract

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 ± 0.026 mag for the flux ratio R(6630/4400)] with respect to the standard combination of light-curve width and color, for which WRMS = 0.204 ± 0.029 mag. When used in combination with the SALT2 color parameter, the color-corrected flux ratio R^c(6420/5290) at maximum light leads to an even lower scatter (WRMS = 0.175 ± 0.025 mag), although the improvement has low statistical significance (<2sigma) 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 ~4300 Å and ~4800 Å. The best flux ratio overall is the color-corrected R^c(4610/4260) at t = -2.5 d from maximum light, which leads to ~30% lower scatter (WRMS = 0.143 ± 0.020 mag) with respect to the standard combination of light-curve width and color, at ~ 2sigma 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.

Appendices are only available in electronic form at http://www.aanda.org

Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
  New!

Find Similar Abstracts:

Use: Authors
Title
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints