Magnetic White Dwarf Stars in the Sloan Digital Sky Survey

TL;DR

This study analyzed SDSS spectra of hydrogen atmosphere white dwarfs to identify magnetic fields via Zeeman splitting, discovering 521 magnetic white dwarfs with fields up to 733 MG, constituting 4% of observed DAs.

Contribution

First large-scale survey of magnetic fields in SDSS white dwarfs, providing statistical insights into magnetic white dwarf occurrence and detection reliability.

Findings

521 magnetic white dwarfs identified

Magnetic fields range from 1 MG to 733 MG

Magnetic white dwarfs constitute 4% of DAs

Abstract

To obtain a better statistics on the occurrence of magnetism among white dwarfs, we searched the spectra of the hydrogen atmosphere white dwarf stars (DAs) in the Data Release 7 of the Sloan Digital Sky Survey (SDSS) for Zeeman splittings and estimated the magnetic fields. We found 521 DAs with detectable Zeeman splittings, with fields in the range from around 1 MG to 733 MG, which amounts to 4% of all DAs observed. As the SDSS spectra have low signal-to-noise ratios, we carefully investigated by simulations with theoretical spectra how reliable our detection of magnetic field was.