Open AccessThe ( 54 Fe+ 58 Ni)/ 56 Ni ratio as a second parameter for Type Ia supernova properties
Author(s) -
Mazzali Paolo A.,
Podsiadlowski Philipp
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society: letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.067
H-Index - 122
eISSN - 1745-3933
pISSN - 1745-3925
DOI - 10.1111/j.1745-3933.2006.00165.x
Subject(s) - supernova , light curve , astrophysics , physics , brightness , ejecta , luminosity , astronomy , galaxy
A variation of the relative content of ( 54 Fe+ 58 Ni) versus 56 Ni may be responsible for the observed scatter of Type Ia supernovae (SNe Ia) about a mean relation between their intrinsic brightness and the shape of their light curve. Synthetic light curves are computed from parametrized Chandrasekhar‐mass explosion models of constant kinetic energy, where the ejecta are divided into an inner nuclear statistical equilibrium (NSE) zone, composed of ( 54 Fe+ 58 Ni) inside and 56 Ni outside, an outer zone with intermediate‐mass elements, and a CO zone. Both the size of the NSE zone and the fraction of ( 54 Fe+ 58 Ni) versus 56 Ni are varied systematically. Models with the same original NSE content but different ( 54 Fe+ 58 Ni)/ 56 Ni ratios reach different peak brightness but have similar light curve shapes. Synthetic spectra indicate that the V ‐band decline rate is not affected by the ( 54 Fe+ 58 Ni)/ 56 Ni ratio. While the 56 Ni mass and the total NSE mass are the dominant parameters that determine the peak luminosity and the shape of the light curve, respectively, a variation in the ( 54 Fe+ 58 Ni)/ 56 Ni ratio, which may depend on the metallicity of the progenitor is likely to account for a significant part of the observed scatter of local SNe Ia about the mean brightness–decline rate relation.