Magnetic white dwarfs from DESI

TL;DR

This paper reports the discovery of 137 new magnetic white dwarfs using DESI spectra, providing a large sample to study their magnetic fields and origins, and demonstrating the power of large-scale surveys in stellar astrophysics.

Contribution

It presents the first large, statistically significant sample of magnetic white dwarfs identified through DESI spectra, aiding in understanding their magnetic field generation.

Findings

Identified 137 new magnetic white dwarfs.

Magnetic field strengths range from 1 to nearly 500 MG.

Demonstrates DESI's effectiveness in uncovering rare stellar objects.

Abstract

A significant fraction of white dwarfs, the degenerate remnants of low- and intermediate-mass stars, host strong magnetic fields; yet, the origin and evolution of these magnetic fields remain poorly understood. Building a large, statistically robust sample of these magnetic white dwarfs (MWDs) is crucial for testing competing theories of field generation. We used the white dwarf candidates catalog from Gaia DR3 to select objects with spectra from the first data release of the Dark Energy Spectroscopic Instrument (DESI) survey. We identified candidate MWDs through visual inspection of their spectra, searching for the characteristic Zeeman splitting of absorption lines. After cross-matching with the literature, we present the discovery of 137 new MWDs. Follow-up analysis and atmospheric modeling were used to determine magnetic field strengths ranging from approximately 1 to nearly 500~MG. Our findings demonstrate the exceptional capability of large-scale spectroscopic surveys, such as DESI, to uncover rare stellar populations and advance our understanding of compact-object astrophysics.