The open-cluster initial-final mass relationship and the high-mass tail of the white dwarf distribution

Recent studies of white dwarfs in open clusters have provided new constraints on the initial-final mass relationship (IFMR) for main-sequence stars with masses in the range 2.5-6.5 M circle dot. We re-evaluate the ensemble of data that determines the IFMR and argue that the IFMR can be characterized by a mean IFMR about which there is an intrinsic scatter. We investigate the consequences of the IFMR for the observed mass distribution of field white dwarfs using population synthesis calculations. We show that while a linear IFMR predicts a mass distribution that is in reasonable agreement with the recent results from the Palomar-Green survey, the data are better fitted by an IFMR with some curvature. Our calculations indicate that a significant (similar to 28) percentage of white dwarfs originating from a single star evolution has masses in excess of similar to 0.8 M circle dot obviating the necessity for postulating the existence of a dominant population of high-mass white dwarfs that arise from binary star mergers.