Influence of the Stellar Population on Type Ia Supernovae: Consequences for the Determination of Ω

The influence of the metallicity at the main sequence on the chemicalstructure of the exploding white dwarf, the nucleosynthesis during theexplosion and the light curves of an individual Type Ia supernovae have beenstudied. Detailed calculations of the stellar evolution, the explosion, andlight curves of delayed detonation models are presented. Detailed stellar evolution calculations with a main sequence mass of 7 M_ohave been performed to test the influence of the metallicity Z on the structureof the progenitor. A change of Z influences the central helium burning and,consequently, the size of the C/O core which becomes a C/O white dwarf and itsC/O ratio. Subsequently, the white dwarf may grow to the Chandrasekhar mass andexplode as a Type Ia supernovae. Consequently, the C/O structure of theexploding white dwarf depends on Z. Since C and O are the fuel for thethermonuclear explosion, Z indirectly changes the energetics of the explosion. In our example, changing Z from Pop I to Pop II causes a change in the zeropoint of the maximum brightness/decline relation by about $0.1^m$ and a changein the rise time by about 1 day. Combined with previous studies, We provide arelation between a change of the rise time in SNeIa and the off-set in thebrightness/decline relation. We find that dM = dt where dM is the offset in therelation and dt is the change of the rise time in days. This relation provides a way to detect and test for evolutionary effects, andto estimate the possible consequences for the determination of the cosmologicalconstant. However, due to uncertainties in the time evolution of the propertiesof the progenitors, we cannot predict whether evolution becomes important atz=0.5, 1 or 2. This question has to be answered by observations.Comment: 8 pages, 5 figures, macros 'aas2pp4.sty'. The Astrophysical Journal (accepted