2006/09/19 by Daniel Kasen, S. E. Woosley · 9 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics #Dimmer #Ejecta #Galaxy #Gamma-ray bursts and supernovae #Light curve #Luminosity #Optics #Physics #Radiative transfer #Stellar, planetary, and galactic studies #Supernova #astro-ph
paper · pdf · doi:10.1086/510375
published as Astrophys.J.656:661-665,2007 · 6 pages, submitted to ApJ
arxiv created 2006/09/19 · openalex publication_date 2007/02/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Brighter Type Ia supernovae (SNe Ia) have broader, more slowly declining B -band light curves than dimmer SNe Ia. We study the physical origin of this width-luminosity relation (WLR) using detailed radiative transfer calculations of Chandrasekhar-mass SN Ia models. We find that the luminosity dependence of the diffusion time (emphasized in previous studies) is in fact of secondary relevance in understanding the model WLR. Instead, the essential physics involves the luminosity dependence of the spectroscopic/color evolution of SNe Ia. Following maximum light, the SN colors are increasingly affected by the development of numerous Fe II/Co II lines that blanket the B band and, at the same time, increase the emissivity at longer wavelengths. Because dimmer SNe Ia are generally cooler, they experience an earlier onset of Fe III to Fe II recombination in the iron group rich layers of ejecta, resulting in a more rapid evolution of the SN colors to the red. The faster B -band decline rate of dimmer SNe Ia thus reflects their faster ionization evolution.