出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Observations of thermonuclear supernovae (SNe Ia) at high-redhift (z) show that the Universe
is dominated by the Dark Energy term, characterized by its negative pressure. SNIa Hubble
diagram, including nowadays 200 of these objects up to z=1.8, strongly favours a decelerated expansion
of the Universe up to z=0.5 and an accelerated one at current time. Taken all current data
together (SNe Ia, Cosmic Microwave Background, Barionic Acoustic Oscillations and Large Scale
Structure) the fraction of the dark energy to the critical density is 70% and its EOS, w=P/r , is
compatible with the cosmological constant or vacuum energy, w=-1, without a temporal dependence.
However, any further attempt to characterize this EOS based on SNe Ia requires to reduce
the present scatter in the Hubble diagram by a factor of 10. Ultimately, systematic effects, like
extinction and evolution with z, and uncontrolled intrinsic dispersion of the light curve shapes will
limit the precision by which SNe Ia could be used to probe the structure of the Universe and its
time evolution. Moreover, observations indicate that brighter SNe Ia occur only in systems with
ongoing star formation and that the majority of SNe Ia comes from young progenitors. In this work
we focus on the scatter of the maximum luminosity of SNe Ia as determined by possible variation
of some properties of their progenitors, namely: (a) mass and metallicity of the progenitor of the
exploding white dwarf and (b) rotational velocity in the framework of double degenerate systems.
We obtain differences up to 0.2 magnitudes at maximum, which are significant to explore the nature
of the dark energy.
