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astro-ph.HE · High Energy Astrophysical Phenomenaastro-ph.IM · Instrumentation and Methods for Astrophysics

Tests with cycle blocks do not reject proportional MAXI curves in three SMC X-1 time ranges from 2012 to 2025

We test whether the mean long-cycle curves of SMC X-1 are proportional in the MAXI 2–4 and 4–10 keV bands. A separate Swift/BAT clock follows changes in cycle length. We select 73 crossing intervals with 3,459 paired daily measurements in 2012–2017, 2018–2023, and 2024–2025. The proportional model has a free positive scale in each range. Both bands have year offsets, orbital terms, and three cycle harmonics. The combined loss is 28.6654. Tests with shared band residual signs give p=0.0972, 0.1110, and 0.1822 for blocks of one, two, and four selected intervals. Thus, the combined test does not reject proportional curves at 5% under these residual models. The middle range passes a corrected secondary test only with two-interval blocks. A planned pooled fit for 2012–2023 gives p=0.0212. Added checks give p=0.2354 with equal weights and p=0.3902 after a daily-label eclipse cut. The positive pooled result is conditional on the fit and sample. Solver checks recover known injected shifts. Conditional injections also show the limited test resolution in the last range, which has only nine selected intervals. The package includes frozen data, code, a full interval ledger, results, figures, and reproduction commands. The primary test conditions on the BAT clock, can miss weak cycles, and does not include all calibration errors. Failure to reject does not prove energy independence or a physical cause.

SMC X-1 · MAXI · Swift BAT · superorbital cycle · X-ray binary · energy dependence · paired profiles · residual resampling · public data · reproducible analysis

Admitted 3 citing publications

References

10
  1. usesFits to SMC X-1 daily X-ray data give cycles near 39 days in early 2025 and 58 days in March to October 2026 sci:sha256:2b844e74a880049c4f649adc1442155a0914ddcf6068a00472ee732c7462cbd2

    We reuse its unchanged, frozen BAT and MAXI daily files. We extend the tested time scope and build a separate BAT crossing clock.

  2. usesMAXI data show no resolved cycle shape difference at 2–4 and 4–10 keV for SMC X-1 at a fixed 57.93-day period in March–October 2026 sci:sha256:0f0b0e8c66e3e049fda3787c14602025cc55f7bbbc55e09a5737d365c989541b

    We extend its proportional-band-curve question to three calendar ranges. We add a changing BAT clock and residual signs shared across several crossing intervals.

  3. Fits with two harmonics give longer bright and faint intervals in selected 2026 SMC X-1 MAXI data than in 2025 sci:sha256:f31ffeb62dc84f08551e32b20d6f295c58b239d799513c3b6f55a89b2507e8bb

    This related study tests bright and faint durations and sample sensitivity in shorter intervals.

  4. doi:10.3847/1538-4357/ab48e4

    This study already reports MAXI hardness changes during parts of the long cycle. Energy changes are not first discovered here.

  5. doi:10.1093/mnras/stad384

    This study gives prior evidence for short cycles and the 2020–2021 excursion.

  6. usesdoi:10.3847/1538-4357/ae1ca6

    We use the orbital frequency model in the version 1 text. Its single-cycle spectral result supplies a comparison with a different energy and time scope.

  7. usesdoi:10.1088/0067-0049/209/1/14

    We use public Swift/BAT daily monitor data described by this reference.

  8. usesdoi:10.1093/pasj/61.5.999

    We use public MAXI daily data from the mission described by this reference.

  9. doi:10.1093/mnras/stag168

    This study supplies prior disk-model and pointed-spectrum context. We do not test its physical model.

  10. doi:10.48550/arXiv.2605.21294

    This study supplies prior optical and MAXI context with a different tested question.

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