Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2012-02-09
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
Measured values of the spectral features (i.e., Appendix B) will be publicly available when the paper is accepted
Scientific paper
In this second paper in a series we present measurements of spectral features of 432 low-redshift (z < 0.1) optical spectra of 261 Type Ia supernovae (SNe Ia) within 20 d of maximum brightness. The data were obtained from 1989 through the end of 2008 as part of the Berkeley SN Ia Program (BSNIP) and are presented in BSNIP I (Silverman et al., submitted). We describe in detail our method of automated, robust spectral feature definition and measurement which expands upon similar previous studies. Using this procedure, we attempt to measure expansion velocities, pseudo-equivalent widths (pEW), spectral feature depths, and fluxes at the centre and endpoints of each of nine major spectral feature complexes. A sanity check of the consistency of our measurements is performed using our data (as well as a separate spectral dataset). We investigate how velocity and pEW evolve with time and how they correlate with each other. Various spectral classification schemes are employed and quantitative spectral differences among the subclasses are investigated. Several ratios of pEW values are calculated and studied. The so-called Si II ratio, often used as a luminosity indicator (Nugent et al. 1995), is found to be well correlated with the so-called "SiFe" ratio and anticorrelated with the analogous "SSi ratio." Furthermore, SNe Ia that show strong evidence for interaction with circumstellar material or an aspherical explosion are found to have the largest near-maximum expansion velocities and pEWs, possibly linking extreme values of spectral observables with specific progenitor or explosion scenarios. [Abridged]
Filippenko Alexei V.
Kong Jason J.
Silverman Jeffrey M.
No associations
LandOfFree
Berkeley Supernova Ia Program II: Initial Analysis of Spectra Obtained Near Maximum Brightness does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Berkeley Supernova Ia Program II: Initial Analysis of Spectra Obtained Near Maximum Brightness, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Berkeley Supernova Ia Program II: Initial Analysis of Spectra Obtained Near Maximum Brightness will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-273799