The rise and fall of type Ia supernova light curves in the SDSS-II supernova survey

摘要: We analyze the rise and fall times of Type Ia supernova (SN Ia) light curves discovered by Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. From a set 391 k-corrected to rest-frame B V bands, we find smaller dispersion in rising portion curve compared decline. This is qualitative agreement with computer models which predict that variations radioactive nickel yield have less impact on than spread decline rates. The differences properties suggest single "stretch" correction phase does not properly model range SN shapes. select subset 105 well observed both portions develop "2-stretch" fit algorithm estimates independently. average time from explosion B-band peak brightness 17.38 ± 0.17 days, but 13 days 23 days. Our shorter 19.5 found previous studies; this reflects different template used application 2-stretch algorithm. SDSS-II local SNe well-observed early show no significant their rise-time properties. slow-declining events tend fast times, distribution minus broad peaked. contrast bimodality parameter was first suggested Strovink an analysis small Ia. divide sample half based value, tr – tf ≤ 2 > search for host galaxy Hubble residuals; difference or residuals our sample.