# Detections and Constraints on White Dwarf Variability from Time-Series GALEX Observations

## TL;DR

This study analyzes ultraviolet time-series data from GALEX to discover and characterize variability in over 23,000 white dwarfs, identifying new pulsators and eclipsing systems despite short observation baselines.

## Contribution

It introduces a novel ranking algorithm to detect white dwarf variability in GALEX data and reports 49 new variable white dwarfs, including pulsators and eclipsing binaries.

## Key findings

- Identified 49 new variable white dwarfs, including 41 pulsators and 8 eclipsing systems.
- Detected variability in sources as faint as Gaia G=20 mag.
- Estimated the occurrence rate of WD 1145+017-like transiting debris systems to be less than 0.5%.

## Abstract

We search for photometric variability in more than 23,000 known and candidate white dwarfs, the largest ultraviolet survey compiled for a single study of white dwarfs. We use gPhoton, a publicly available calibration/reduction pipeline, to generate time-series photometry of white dwarfs observed by GALEX. By implementing a system of weighted metrics, we select sources with variability due to pulsations and eclipses. Although GALEX observations have short baselines (< 30 min), we identify intrinsic variability in sources as faint as Gaia G = 20 mag. With our ranking algorithm, we identify 49 new variable white dwarfs (WDs) in archival GALEX observations. We detect 41 new pulsators: 37 have hydrogen-dominated atmospheres (DAVs), including one possible massive DAV, and four are helium-dominated pulsators (DBVs). We also detect eight new eclipsing systems; five are new discoveries, and three were previously known spectroscopic binaries. We perform synthetic injections of the light curve of WD 1145+017, a system with known transiting debris, to test our ability to recover similar systems. We find that the 3{\sigma} maximum occurrence rate of WD 1145+017-like transiting objects is < 0.5%.