Searching for Magnetic White Dwarfs in LAMOST DR10

TL;DR

This study leverages LAMOST DR10 spectra, combined with Gaia and SDSS data, to identify and characterize 63 magnetic white dwarfs, including 32 new discoveries, demonstrating the survey's potential for expanding the known MWD population.

Contribution

First systematic identification and characterization of MWDs in LAMOST DR10, including new discoveries, using Zeeman splitting in low-resolution spectra.

Findings

Identified 63 isolated MWDs in LAMOST DR10, 32 of which are new.

Measured magnetic field strengths from a few MG to several tens of MG.

LAMOST spectra can effectively detect and analyze MWDs, consistent with previous SDSS measurements.

Abstract

Magnetic white dwarfs (MWDs) are key to understanding the origin and evolution of magnetic fields in compact stars. While large spectroscopic surveys such as SDSS have greatly expanded the known sample, the potential of LAMOST has not yet been fully explored. Our aim is to identify and characterize isolated MWDs in the LAMOST DR10 database. We cross-matched LAMOST DR10 spectra with white dwarf candidates from Gaia EDR3 and with recent SDSS-based catalogs of MWDs. Zeeman splitting in Balmer and helium absorption lines was used as the primary diagnostic to identify magnetic fields and to estimate their strengths. Reference objects from SDSS catalogs were used to test the detectability of MWDs in LAMOST low-resolution spectra. We identified 63 isolated MWDs in LAMOST DR10, of which 32 are new discoveries. Surface magnetic field strengths were measured from Zeeman splitting, covering a range from a few MG up to several tens of MG. For previously known SDSS MWDs, our LAMOST-based field measurements show mostly agreement with published values. This work demonstrates the capability of LAMOST low-resolution spectroscopy to identify and characterize isolated MWDs. The newly discovered objects expand the known population and provide valuable targets for future high-resolution spectroscopic and polarimetric follow-up studies. Our results highlight the potential of combining LAMOST with Gaia and other large surveys to build a more complete census of MWDs.