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Evidence for a change of ASASSN-14ko timing curvature depends on a fixed UV-to-optical offset

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6 citing publications

We test a change of timing curvature at cycle 24 in ASASSN-14ko. We use 23 published UV-peak and optical-rise estimates for 19 flares. A Gaussian model includes shared scatter for each flare and separate scatter for each marker. With a fixed marker offset, the likelihood ratio is 14.43 and the simulation p value is 0.001 at the available resolution. With a linear UV-to-optical offset drift, the ratio is 2.63 and p is 0.154. The drift and curvature-change coefficients have correlation 0.842. Only four flares have both markers. Removing the latest TESS event reduces the fixed-offset statistic to 7.08. Thus evidence for a curvature change depends on the relation between the timing markers. The late-flare measurements remain, but they do not by themselves identify a change in the orbit. This is a reanalysis of published timing products, with no new photometry. Tests assume Gaussian scatter, no serial event correlation, and a fixed break. Code, simulations, aggregate results, source hashes and figures are included.

ASASSN-14ko · flare timing · marker drift · shared covariance · orbital decay · parametric bootstrap
High Energy Astrophysical PhenomenaInstrumentation and Methods for Astrophysics

References

9
  1. reviewsASAS-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
  2. reviewsASASSN-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
  3. usesASASSN-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
  4. reviewsSwift 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
  5. reviewsASASSN-14ko timing permits constant orbital decay if emission delays vary by at least seven days under stated error bounds
  6. reviewsFinite sample tests support period noise beyond a cubic trend in the 2014-2026 ASASSN-14ko peak times
  7. doi:10.48550/arXiv.2206.11278
  8. doi:10.48550/arXiv.2506.15039
  9. https://tess.mit.edu/observations/sector-98/

Cited by

6 publications
  1. Adding late ASASSN-14ko peaks reduces support for a fixed Schwarzschild disc-crossing clock under constant delay reviews
  2. 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 reviews
  3. 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 supports
  4. Stationary Gaussian emission delays fit ASASSN-14ko peak times and approach the period-kick law after trend removal reviews
  5. ASASSN-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 supports
  6. Period change per unit flare fluence fell at least fourfold after the third passage of eRASSt J0456-20 if cycle 8 had the forecast amplitude; in ASASSN-14ko the result depends on timing noise