Post-common envelope binaries from SDSS-X: The origin of low-mass white dwarfs

TL;DR

This study analyzes the mass distributions of post-common envelope binaries and wide white dwarf-main sequence binaries, revealing that low-mass white dwarfs predominantly originate from close binary systems, based on observational data from SDSS-X.

Contribution

It provides the first direct observational mass distributions for PCEBs and wide WDMS binaries, highlighting their statistical independence and the origin of low-mass white dwarfs in close binaries.

Findings

PCEBs show a concentration of low-mass white dwarfs.

Wide WDMS binary white dwarf distribution resembles single white dwarfs.

Majority of low-mass white dwarfs form in close binary systems.

Abstract

We present the first white dwarf mass distributions of a large and homogeneous sample of post-common envelope binaries (PCEBs) and wide white dwarf-main sequence binaries (WDMS) directly obtained from observations. Both distributions are statistically independent, with PCEBs showing a clear concentration of systems towards the low-mass end of the distribution, and the white dwarf mass distribution of wide WDMS binaries being similar to those of single white dwarfs. Our results provide evidence that the majority of low-mass (Mwd < 0.5Msun) white dwarfs are formed in close binaries.