Mass-radius relation of white dwarfs

Jointly with a photometric analysis, formalized by a Bayesian inference method, we measured precise radii for the white dwarfs in our sample, which allowed us to directly measure the white dwarf masses from their gravitational redshifts. The distributions of measured masses and radii agree within 6% (at the 1-{sigma} level) from the theoretical mass-radius relation, thus delivering a much smaller scatter in comparison with previous analyses that used gravitational redshift measurements from low-resolution spectra.

Our comparison against model-dependent spectroscopic estimates produces a larger scatter of 15% on the mass determinations. We find an agreement within ~10% from previous model-based, photometric mass estimates from the literature. Combining gravitational redshift measurements and photometric analysis of white dwarfs delivers precise and accurate empirical estimates of their masses and radii.

This work confirms the reliability of the theoretical mass-radius relation from the lightest to the heaviest white dwarfs in our sample (~0.38-1.3M_{sun}_).