Analysis of the Hydrogen-rich Magnetic White Dwarfs in the SDSS

TL;DR

This study models and analyzes the spectra of hydrogen-rich magnetic white dwarfs from SDSS, revealing their magnetic field distributions and geometries using a comprehensive spectral fitting approach.

Contribution

It introduces a method to analyze SDSS spectra of magnetic white dwarfs using a least-squares minimization with an evolutionary algorithm, covering a wide range of magnetic field strengths.

Findings

Distribution of magnetic field strengths in the sample

Magnetic field geometries of the white dwarfs

Identification of new magnetic white dwarfs in SDSS

Abstract

We have calculated optical spectra of hydrogen-rich (DA) white dwarfs with magnetic field strengths between 1 MG and 1000 MG for temperatures between 7000 K and 50000 K. Through a least-squares minimization scheme with an evolutionary algorithm, we have analyzed the spectra of 114 magnetic DAs from the SDSS (95 previously published plus 14 newly discovered within SDSS, and five discovered by SEGUE). Since we were limited to a single spectrum for each object we used only centered magnetic dipoles or dipoles which were shifted along the magnetic dipole axis. We also statistically investigated the distribution of magnetic-field strengths and geometries of our sample.