Classifying white dwarfs from multi-object spectroscopy surveys with machine learning

Munday, James; Tremblay, Pier-Emmanuel; Pelisoli, Ingrid; Killestein, Thomas; Martikainen, Julia; Jones, David; Bédard, Antoine; Sowicka, Paulina
Bibliographical reference

Monthly Notices of the Royal Astronomical Society

Advertised on:
3
2026
Number of authors
8
IAC number of authors
3
Citations
0
Refereed citations
0
Description
With tens to hundreds of spectra of white dwarfs being taken each night from multi-object spectroscopic surveys, automated spectral classification is essential as part of efficient data processing. In this study, we design a neural network to classify the spectral type of white dwarfs using a combination of spectra from the Dark Energy Spectroscopic Instrument (DESI) data release 1 and imaging from Pan-STARRS photometry. The trained network has a near 100 per cent accuracy at identifying DA and DB white dwarf spectral types, while having an 85─95 per cent accuracy for identifying all other primary types, including metal pollution. Distinct spectral or photometric features map into separate structures when performing a Uniform Manifold Approximation and Projection (UMAP) dimensionality reduction. Investigating further and looking at multiple epoch spectra, we performed a separate search for objects that have strongly changing spectral signatures using UMAP, discovering three new inhomogeneous surface composition (double-faced) white dwarfs in the process. We lastly show how machine learning has the potential to separate single white dwarfs from double white dwarf binary star systems in a large data set, ideal for isolating a single star population. The results from all of these techniques show a compelling use of machine learning to boost efficiency in analysing white dwarfs observed in multi-object spectroscopy surveys, at times replacing the need for human-driven spectral classifications. This demonstrates our techniques as powerful tools for batch population analyses, finding outliers as a form of rare subclass detection, and in conducting multi-epoch spectral analyses.
Type