Spectral luminosity indicators in SNe la - The R(Si II) line strength ratio

Stephan Hachinger, Paolo A. Mazzali, Masaomi Tanaka, Wolfgang Hillebrandt, Stefano Benetti

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The remarkable homogeneity of SNe la is the basis for their cosmological use. To a first approximation, their B-band light curves form a one-parameter family, so that the B maximum luminosity can be inferred from the light curve shape. Another possibility for luminosity calibration are spectral parameters that correlate with luminosity. The "luminosity indicator" which has received perhaps the largest attention is R(Si II) [1], the ratio of the strengths of the Si II λ5912 and λ6355 lines. Using radiative transfer models, we explain the R(Si II) behaviour as an ionization effect: Si II λ5972 is stronger in dimmer objects because of a much larger Si Il/Si III ratio, and Si II λ6355 shows no trend because of saturation. This explains the rise in R(Si II), but also leads to the conclusion that the strength of Si II λ5912 itself is a more direct spectroscopic luminosity indicator However, even the most direct spectroscopic luminosity indicators are likely to be affected by the intrinsic variability of SN la spectra. The resulting uncertainties may be minimised if several indicators [2] are used to obtain an average result and an error estimate. The accuracy of such a method remains to be investigated.

Original languageEnglish
Title of host publicationProbing Stellar Populations Out To The Distant Universe - Cefalu 2008 - Proceedings of the International Conference
Pages573-576
Number of pages4
DOIs
Publication statusPublished - 2009
Externally publishedYes
EventInternational Conference on Probing Stellar Populations Out To The Distant Universe, Cefalu 2008 - Cefalu, Sicily, Italy
Duration: 2008 Sep 72008 Sep 19

Publication series

NameAIP Conference Proceedings
Volume1111
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

OtherInternational Conference on Probing Stellar Populations Out To The Distant Universe, Cefalu 2008
Country/TerritoryItaly
CityCefalu, Sicily
Period08/9/708/9/19

Keywords

  • Cosmic distances
  • Line formation
  • Radiative transfer
  • Spectroscopy
  • Supemovae la

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Fingerprint

Dive into the research topics of 'Spectral luminosity indicators in SNe la - The R(Si II) line strength ratio'. Together they form a unique fingerprint.

Cite this