The impact of mergers in the mass distribution of white dwarfs

TL;DR

This paper investigates whether the structure observed in white dwarf mass distributions is caused by mergers, using a simplified population synthesis model, and concludes that mergers are unlikely the main cause.

Contribution

The study introduces a simplified population synthesis model that carefully avoids artifacts, providing new insights into the origins of white dwarf mass distribution features.

Findings

Structures in the mass distribution are probably not caused by mergers.

The model offers insights into close binary evolution.

Mergers are unlikely the primary source of observed structures.

Abstract

Recent surveys have allowed to derive the white dwarf mass distribution with reasonable accuracy. This distribution shows a noticeable degree of structure that it is often attributed to the evolution of close binaries in general, and to mergers in particular. To analyze if the origin of this structure can be attributed to the merger of double white dwarfs, we have used a simplified population synthesis model that retains the essential processes of formation of double degenerate binaries. Special care has been taken to avoid artifacts introduced by discontinuities in the distribution functions. Our result is that these structures are not probably due to mergers, but they can provide a deep insight on the evolution of close binary systems.