A blind ZTF DR24 search of 91,009 Gaia white dwarfs finds four deep 2022-2025 dimming events, one not reported before, and only 1 of 6 published debris candidates stays highly variable

Question: Do published debris-transit white dwarf (WD) candidates stay active after ZTF DR10, and does a blind search of later ZTF data find new deep dimming events? Approach: We took 91,009 Gaia EDR3 WD candidates (Gentile Fusillo et al. 2021 catalogue, the Bhattacharjee et al. 2025 cuts, Dec > -30 deg) and ZTF DR24 g and r light curves from the SNAD mirror. We calculated variability metrics in two windows: 2018-03 to 2022-01-05 (the DR10 span) and 2022-01-05 to 2025-10-30. We flagged 20-day binned dimming episodes and dip-shaped top-1 % variability, triaged 168 flagged WDs, and tested the remaining events against same-CCD comparison stars. We injected 6,800 grey dips into real light curves to measure detection efficiency. Results: The variability rank of the population persists (Spearman 0.64; 61 % of the earlier top 1 % stay top 1 %). Only 1 of the 6 Bhattacharjee et al. candidates (WD J0923+7326) and 2 of 8 known debris systems stay in the top 1 %. Several known systems also became quiet, so a quiet period does not refute a candidate. The blind search finds four deep, long, grey events: WD J2327+0019, WD J1944-2451 and WD J0015+3038, which van Roestel et al. (2026) report independently, and WD J0558-1449 (Gaia DR3 2992629136205665152, G = 19.86), which they do not list. WD J0558-1449 fades from 2024-09 to median 0.68 (g) and 0.72 (r) and is still faint at the end of the data. In each window the WDs are fainter than all 17 to 444 same-CCD comparison stars. The search detects 59-65 % of 100-day dips 30-50 % deep; seasonal gaps cause most misses. The onset rate of events at least 45 % deep in previously quiet WDs is 1.6e-5 per WD per year (95 % range 3.4e-6 to 4.8e-5), in agreement with van Roestel et al. Limitations: The light curves contain detections only, so total disappearances become gaps and depths are lower limits. WD J0558-1449 has only ZTF data and needs spectroscopy and independent photometry. Triage includes visual inspection. The rates rest on 2 to 4 events.

white dwarfs · transiting debris · planetary debris · ZTF · Gaia · dimming events · out-of-sample test · injection-recovery · occurrence rate · WD J0558-1449