Abstract
We have developed a quantitative, empirical method for estimating the age of Type Ia supernovae (SNe Ia) from a single spectral epoch. The technique examines the goodness of fit of spectral features as a function of the temporal evolution of a large database of SNe Ia spectral features. When a SN Ia spectrum with good signal-to-noise ratio over the rest frame range 3800 to 6800 Å is available, the precision of a spectral feature age (SFA) is (1σ) ∼1.4 days. SFA estimates are made for two spectral epochs of SN 1996bj (z=0.574) to measure the rate of aging at high redshift. In the 10.05 days which elapsed between spectral observations, SN 1996bj aged 3.35±3.2 days, consistent with the 6.38 days of aging expected in an expanding Universe and inconsistent with no time dilation at the 96.4% confidence level. The precision to which individual features constrain the supernova age has implications for the source of inhomogeneities among SNe Ia.
Original language | English |
---|---|
Pages (from-to) | 722-729 |
Number of pages | 8 |
Journal | Astronomical Journal |
Volume | 114 |
Issue number | 2 |
DOIs | |
Publication status | Published - Aug 1997 |