TESS 2-minute data of 4,265 white dwarfs within 100 pc show no new on-target transit; the search recovers WD 1856+534 b and puts a new 17.12 d eclipse on a nearby M dwarf

Question: Do the public TESS 2-minute light curves of nearby white dwarfs (WDs) contain new transiting planets, eclipsing companions or unexplained dips? Approach: We matched 16,676 Gaia EDR3 WDs within 100 pc to the TESS 2-minute target lists of sectors 1 to 56. We then took all 22,150 SPOC light curves (sectors 1 to 107) of 4,313 TIC targets (4,265 WDs). We ran a box least-squares search (P = 0.15 to 13 d) on the first and last sector of each target and a single-dip matched filter on all sectors. We applied automated vetting (shape, periodogram, physical depth, duration for a companion of 0.5 solar radii or less, repetition in other sectors), manual inspection, difference imaging of target pixel files, catalogue checks and 1,200 transit injections. Results: The search recovers WD 1856+534 b. No new periodic transit or eclipse is on a WD. Of 276 WDs with transit-like detections, 259 fail the automated tests and 16 of the remaining 17 are blends, systematics or weak, unconfirmed signals. Low crowding values are the main cause: in the median sector the WD supplies 34 % of the aperture flux. Difference imaging puts a 17.123503 +/- 0.000019 d, 2.5 h eclipse in the aperture of GALEX J081240.0-760437 on the M dwarf Gaia DR3 5210617837762868864 (20 arcsec away). We found no catalogue entry for this eclipsing binary. The same method puts a 9.135 d signal near HE 0330-0002 on the known eclipsing binary HD 22064. Known asteroids brighter than V = 16 are near the target at 26 of 200 isolated single-dip times and at 0 of 200 control times (p = 1.3e-8): background over-subtraction causes these dips. Injection-recovery gives 95 % upper limits on the planet rate per WD of 1.7 % (4 to 15 Earth radii, P = 0.15 to 1 d) and 9.2 % (1 to 4 Earth radii, P = 0.15 to 1 d). Limitations: BLS used two sectors per target. The completeness includes only the automated cuts. WDs with first 2-minute data after sector 56 are missing. Blends in crowded apertures can hide or imitate WD transits. A spectroscopic orbit is necessary to confirm the new M-dwarf binary.

white dwarfs · TESS · transit search · box least squares · eclipsing binary · blends · difference imaging · asteroids · false positives · occurrence rate · WD 1856+534 b · injection-recovery · null result