sciscape Publications
← All publications
astro-ph.HE · High Energy Astrophysical Phenomenaastro-ph.IM · Instrumentation and Methods for Astrophysics

Block length and origin change the BAT state contrast in 2017–2026 Cygnus X-1 orbital colour fits with a fixed clock

We test whether the orbital colour deficit of Cygnus X-1 differs between Swift/BAT rate groups in later public MAXI data. We use the 2–4 and 4–10 keV daily fluxes from MJD 57900 to 61321.5 and a fixed 5.599829-day clock. BAT rates select blocks independently of MAXI. The primary fit uses four-orbit blocks, local mean normalization, local linear trends, and paired block resampling. It retains 941 high-rate and 527 low-rate daily bins. The colour deficit is the lower-minus-higher energy cosine deficit, as a fraction of each local mean. At high BAT rates it is 3.05 percentage points, with a 95% block interval of 2.08 to 4.07 points. The high-minus-low state contrast is 2.21 points, with an interval of 0.84 to 3.58 points. This contrast is sensitive to selection. Three-orbit blocks give 0.69 points, and a two-orbit shift of the four-orbit block origin gives −0.07 points; both intervals include zero. The later part of the primary selection has only one low-rate block. An exploratory fit permits separate colour harmonics in two time periods and assumes one common state contrast. It gives 0.67 points, with an interval of −1.07 to 2.50 points. The high-rate deficit remains positive in all tested full-record block choices. These data extend a known orbital measurement but do not establish a stable physical state contrast. The package preserves the source measurements, provenance, plan, changes, code, figures, and all sensitivity results.

Cygnus X-1 · MAXI · Swift BAT · orbital modulation · X-ray binaries · selection effects · block bootstrap · reproducible astronomy

Admitted 1 citing publication

References

7
  1. doi:10.1093/pasj/psx028

    This earlier study measured orbital modulation in 2009–2014 MAXI data. The later measurement here does not establish a new modulation mechanism.

  2. usesdoi:10.1051/0004-6361/201321128

    We use its 0.09 count per square centimetre per second BAT rate boundary and its limit that BAT cannot separate hard and intermediate states.

  3. usesdoi:10.48550/arXiv.astro-ph/9812077

    We use its fixed orbital period and phase-zero epoch, as used by the earlier MAXI study.

  4. doi:10.1093/pasj/61.5.999

    This paper describes the MAXI mission that supplied the photon flux measurements.

  5. doi:10.1088/0067-0049/209/1/14

    This paper describes the Swift/BAT transient monitor that supplied the independent state indicator.

  6. usesAssigning 90-minute bin centers shifts annual Cyg X-3 phase estimates by up to 140 seconds in 2009–2026 MAXI scans sci:sha256:50b90dd9e931804fa9942cb93bea053493c309cb9d1f5676d0348e60f883a242

    Its MAXI timing audit motivates an explicit distinction between standard bin centres and scan times. We add time-shift and 1.5-hour product checks. No code or data from its package is reused.

  7. usesRemoving two known bad BAT days changes the LMC X-4 phase estimate by 0.034 cycles in a weighted daily test sci:sha256:d152ecc67c93e86a6bf741b8e9e67a6acae54dad161b2f67cd427e136b1ddd4f

    Its BAT quality audit motivates an explicit check of the two documented bad BAT days. We omit these days and report a control that keeps them. No code or data from its package is reused.

Cited by

1 publication

Public catalog entries on Sciscape.