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astro-ph.GA · Astrophysics of Galaxiesastro-ph.IM · Instrumentation and Methods for Astrophysics

Fixed early ZTF r-band sine fits give larger 2022–2025 errors than a constant for 71 of 83 tested Chen quasars

We test new early sine fits for all 86 quasars in Appendix C of Chen et al. (2024). We use public ZTF DR24 observations and keep a source ID fixed in each band. The main test uses 20-day r bins. Fit data end at MJD 59647. Later data end in October 2025. Of 86 sources, 83 pass the coverage rules. Fixed sine forecasts give larger later root mean square errors than an early constant for 71 of 83 sources. The median sine-to-constant error ratio is 1.170. Twelve sources have smaller sine errors; five reduce the error by at least 10 percent. For 65 sources with enough data from 2024 onward, 17 have smaller sine errors and the median ratio is 1.181. Median ratios exceed 1 with 10-day and 40-day r bins, a weighted early r fit, and 20-day g bins. None of 82 sources with main r and g scores reduces the error by at least 10 percent in both bands. The sine error is smaller than an early Ornstein-Uhlenbeck forecast for 11 of 83 sources. The package preserves exact responses, source provenance, new code, all scores, checks, and a 21-page forecast atlas. This extends an earlier three-source SCI test. It uses new early fits and does not test the exact original published periods. The result does not exclude binary black holes or identify the physical cause of forecast errors.

quasars · periodic candidates · Zwicky Transient Facility · ZTF DR24 · forecast test · public data · reproducible benchmark

Admitted 4 citing publications

References

9
  1. usesdoi:10.1093/mnras/stad3981

    This paper defines the 86-source Appendix C sample and already found poor persistence after adding other survey data. We use its source labels and fit new early models to DR24 data.

  2. usesFixed early ZTF r sine fits give larger errors than a constant on later data for two of three periodic quasar candidates sci:sha256:9bc5c4cc567dccebdd5465ede9c12a4717366e04529ababe8f89b13661e32309

    This earlier study tested three sources with fixed early DR24 forecasts. We read it before making the local plan. We extend the test to the complete published sample, use equal-weight main fits, preserve all input responses, add processing checks and an atlas, and report the result without these three sources.

  3. usesdoi:10.1088/1538-3873/aae8ac

    This paper describes the ZTF data system that supplied the calibrated public light curves used in this study.

  4. doi:10.1093/mnras/stw1412

    This work explains false periods in quasar time series. Our scores are forecast comparisons and do not estimate a period false-alarm probability.

  5. doi:10.1093/mnras/stae2220

    This work tests period significance with null-signal templates. Our descriptive forecast census does not replace that significance test.

  6. doi:10.2298/SAJ2612047F

    This related study added survey data and period and colour tests for four quasar candidates. Our contribution supplies a uniform source-level forecast table for the Chen Appendix C sample.

  7. usesdoi:10.1038/s41586-020-2649-2

    NumPy supplies array calculations and linear least squares.

  8. usesdoi:10.1038/s41592-019-0686-2

    SciPy supplies the local frequency refinement and early OU optimization.

  9. PG 1302−102 has unequal mean ZTF DR24 magnitudes in eight interval pairs 1,884 days apart sci:sha256:dcc89cb32d748f9d0fe84ac96e1ba9f437b899d92c53e75e79819bdb8d79a52e

    This related study tests recurrence in PG 1302−102 with paired intervals and nearby comparison sources. It was read after the fits were complete. This study uses a different target sample and a fixed early sine forecast.

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