SDSS White Dwarf mass distribution at low effective temperatures

TL;DR

This paper investigates the observed increase in surface gravity of DA white dwarfs at low temperatures in SDSS data, exploring potential explanations and suggesting that convection modeling deficiencies may be responsible.

Contribution

It analyzes the temperature-dependent surface gravity increase in SDSS white dwarfs and proposes that convection modeling issues likely cause this effect.

Findings

Surface gravity increases at temperatures below 11500 K.

Uncertainties in atmospheric models may influence mass estimates.

Convection modeling deficiencies are a probable cause.

Abstract

The DA white dwarfs in the Sloan Digital Sky Survey, as analyzed in the papers for Data Releases 1 and 4, show an increase in surface gravity towards lower effective temperatures below 11500 K. We study the various possible explanations of this effect, from a real increase of the masses to uncertainties or deficiencies of the atmospheric models. No definite answer is found but the tentative conclusion is that it is most likely the current description of convection in the framework of the mixing-length approximation, which leads to this effect.