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Public ZTF data show a constant AT2023uqm period while its flare fluence grew 1.6-fold per flare; one energy-proportional clock for three periodic nuclear transients fails only for some markers

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Question: do the flare clocks of the three best-timed periodic nuclear transients (ASASSN-14ko, eRASSt J0456-20, AT2023uqm) follow one law in which the orbit loses energy in proportion to the radiated flare energy? Approach: we measured the five AT2023uqm flares again in public ZTF data-release light curves (2018-2025), with a seeing-dependent host model and two-Gaussian flare fits. For each source we fitted timing models with free jitter, including an energy-coupled clock (each passage changes the period by -k times its flare energy). A Monte Carlo over black-hole mass, stellar mass and bolometric energy converted k to Q, the orbital energy lost per passage over the radiated energy, and a simulation-calibrated likelihood-ratio test checked one common Q. Results: our AT2023uqm markers agree with the published markers within 0.0-2.7 d. The fluence grows by 1.59 +/- 0.07 per flare (r), but the period change per passage is +0.03 +/- 0.80 d (first peak) or +0.8 +/- 1.1 d (dip), and k is consistent with zero. The first peak moves earlier relative to the dip by 1.3 +/- 0.4 d per flare, so the period depends on the marker (524.45 to 527.06 d). For J0456-20 the energy-coupled clock fits cycles 1-5 as well as the best broken clock and forecasts cycles 6-7 with |z| <= 1.7 (X-ray weights). For ASASSN-14ko it is worse than a break in the period derivative. Q is 0.025 (95%: 0.003-0.21) for ASASSN-14ko and 0.023 (0.001-0.47) for J0456-20 (black-hole mass 1e7); these agree (p = 0.79). AT2023uqm disagrees with each of them for the dip marker (p = 0.015, 0.007); the three-source test gives p = 0.025 for the dip, but 0.11 with 2 d of extra jitter and 0.25 for the first peak. Q << 1 everywhere, so orbital energy does not power the flares. Gravitational waves and tidal heating cannot supply the ASASSN-14ko and early J0456-20 period decreases; drag needs discs of about 1-15 Msun, and mass-loss kicks explain J0456-20 only for a black-hole mass near 1e5. Limitations: few AT2023uqm times per marker, PSF photometry with host light, band-limited energies, black-hole masses uncertain by 0.3-2 dex, and no public data for the 2026 flares.

AT2023uqm · ASASSN-14ko · eRASSt J0456-20 · repeating partial tidal disruption · flare timing · orbital decay · ZTF data release · energy coupling · timing marker drift
High Energy Astrophysical PhenomenaAstrophysics of Galaxies

References

17
  1. uses, supportsASASSN-14ko flares were not weaker in 2022-2024 than in 2017-2021 while the period decrease slowed; a period change proportional to flare energy fails if the slowdown is real
  2. uses, challengesSwift and XMM-Newton data from 2023-2024 show two more X-ray flare cycles of eRASSt J0456-20: the recurrence time stays at 193 days and the flares fade by a factor of two per cycle
  3. usesASAS-SN and TESS peak times of ASASSN-14ko flares in 2022-2026 drift 2.2 days per cycle later than the published decaying-period ephemeris; the period stays near 108 days
  4. ASASSN-14ko flares from 2022 to 2026 peak up to 21 days later than the published constant period-derivative ephemeris; random period changes of about 0.6 days per orbit fit the peak times better
  5. ASASSN-14ko flares in 2023-2025 occur up to 21 days later than the Payne et al. 2022 ephemeris predicts, and the period decrease became slower after 2021
  6. Swift data show no third flare of AT2018fyk in the 2025 windows that the repeating partial disruption model predicted; a copy of the 2022 flare that starts before December 2025 is below 5% in UV
  7. supportsASASSN-14ko timing permits constant orbital decay if emission delays vary by at least seven days under stated error bounds
  8. Finite sample tests support period noise beyond a cubic trend in the 2014-2026 ASASSN-14ko peak times
  9. supportsEvidence for a change of ASASSN-14ko timing curvature depends on a fixed UV-to-optical offset
  10. SPHEREx near-infrared images show that the September 2025 ASASSN-14ko flare peaked 21 days after the Payne et al. 2022 ephemeris; the August 2026 flare peak time depends on its decline time
  11. useshttps://arxiv.org/abs/2510.26561
  12. useshttps://arxiv.org/abs/2401.14091
  13. useshttps://arxiv.org/abs/2208.12452
  14. useshttps://arxiv.org/abs/2009.03321
  15. https://arxiv.org/abs/2309.15849
  16. https://arxiv.org/abs/2606.06578
  17. useshttps://irsa.ipac.caltech.edu/Missions/ztf.html

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