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Paper: Rates and Progenitors of Type Ia Supernovae
Volume: 342, 1604-2004: Supernovae as Cosmological Lighthouses
Page: 140
Authors: Mannucci, F.
Abstract: We have used the Two Micron All Sky Survey near-infrared galaxy magnitudes to compute the supernova (SN) rates normalized to the stellar mass of the parent galaxies. The rates of all SN types show a sharp dependence on both the morphology and the B—K color of the galaxy. In particular, the Type Ia SN rate in the galaxies bluer than B—K=2.6 is about a factor of 30 larger than in galaxies with B—K>4.1. This dependence implies that a significant fraction of Type Ia SNe must originate in a young stellar population closely following the evolution of the star formation rate.

This result seems in contradiction with the recent observations of Type Ia SN rate in the Great Observatories Origins Deep Survey (GOODS) fields: at high redshift rates are best fit by the presence of long delay times between progenitor formation and SN explosion. This discrepancy is only apparent: both results can be explained by assuming that Type Ia SNe originate from two different populations, characterized by very different delay times: about half of the SNe Ia derive from a relatively young stellar population (fast exploders), the other half comes from old stellar populations having delay times of 2—4 Gyrs (slow exploders). Since the two populations dominate at different redshifts, the use of Ia SNe as cosmological standard candles can be questioned. Details are given in two papers by Mannucci et al. (2004a,b).

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