White Dwarf Luminosity and Mass Functions from Sloan Digital Sky Survey Spectra

TL;DR

This paper uses SDSS data to create detailed white dwarf luminosity and mass functions, addressing observational biases and spectral line issues, resulting in the largest spectroscopically confirmed WD sample to date.

Contribution

It introduces a method to correct for spectral line profile issues and derives the most extensive white dwarf luminosity function from SDSS data.

Findings

Derived a selection probability as a function of color and magnitude.

Addressed the upturn in log g for cool white dwarfs and proposed a correction method.

Presented a white dwarf luminosity function with over 3,300 confirmed WDs.

Abstract

We present the first phase in our ongoing work to use Sloan Digital Sky Survey (SDSS) data to create separate white dwarf (WD) luminosity functions for two or more different mass ranges. In this paper, we determine the completeness of the SDSS spectroscopic white dwarf sample by comparing a proper-motion selected sample of WDs from SDSS imaging data with a large catalog of spectroscopically determined WDs. We derive a selection probability as a function of a single color (g-i) and apparent magnitude (g) that covers the range -1.0 < g-i < 0.2 and 15 < g < 19.5. We address the observed upturn in log g for white dwarfs with Teff <~ 12,000K and offer arguments that the problem is limited to the line profiles and is not present in the continuum. We offer an empirical method of removing the upturn, recovering a reasonable mass function for white dwarfs with Teff < 12,000K. Finally, we present a white dwarf luminosity function with nearly an order of magnitude (3,358) more spectroscopically confirmed white dwarfs than any previous work.