WD ages from Gaia EDR3 wide double WD binaries

However, self-consistent validation of the methods for determining WD total ages has yet to be widely performed. This work uses 1565 wide (>100au) WD+WD binaries and 24 new triples containing at least two WDs to test the accuracy and validity of WD total age determinations.

For these 1589 wide double WD binaries and triples, we derive the total age of each WD using photometric data from all-sky surveys, in conjunction with Gaia parallaxes and current hydrogen atmosphere WD models. Ignoring the initial-to-final mass relation and considering only WD cooling ages, we find that roughly 21%-36% of the more massive WDs in a system have a shorter cooling age. Since more massive WDs should be born as more massive main-sequence stars, we interpret this unphysical disagreement as evidence of prior mergers or the presence of an unresolved companion, suggesting that roughly 21%-36% of wide WD+WD binaries were once triples.