A Quantitative Spectroscopic Comparison of Distant and Nearby Type Ia Supernovae: Tests for Homogeneity and Implications for Cosmology
Abstract
This thesis presents quantitative analysis of spectra from 130 high-redshift (Zmedian = 0.63) Type Ia supernovae. This extensive set of distant SNe is comprised of a primary set of objects observed at the Gemini telescopes for the ongoing Supernova Legacy Survey (SNLS), a secondary set observed at the Very Large Telescope for the SNLS, and a tertiary set of high-z spectra from the literature. All work on the reduction and identification of the spectra in the primary data set (including spectra from a total of 124 SNe candidates observed between August 2003 and May 2006) was completed by the author. Rest-frame equivalent width and Call H&K ejection velocity measurements are made on these distant SNe Ia spectra, with methods tailored to the specific considerations of high-z data. The results from this analysis were compared to corresponding measurements from a set of 167 SNe Ia spectra from 24 nearby objects from the literature to investigate the homogeneity of SNe Ia across a wide range of redshifts (0.001 less than or equal z less than or equal 1.0). This comparison provides a quantitative indicator for possible evolutionary effects in the population of high-z SNe surveyed for cosmology. A statistical comparison of the spectroscopic features of the high-z SNe and the trends exhibited in the nearby objects finds a less than 2 sigma difference for all of the measurements considered here. These results also indicate that there are no systematic changes due to redshift in this SNe sample. The dependence of SNe Ia spectroscopic properties on host galaxy type is also investigated and found to be similar for nearby and distant objects. These results are discussed briefly in the context of the physical understanding and cosmological implications of SNe Ia. A new correlation between SNe Ia peak magnitude and the strength of a specific SiII absorption feature (near 4000 A, measured within +/- 7 days of maximum light) is also presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 14, 2006
- Accession Number
- ADA462901
Entities
People
- T. J. Bronder
Organizations
- University of Oxford