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astro-ph.SR · Solar and Stellar Astrophysicsastro-ph.IM · Instrumentation and Methods for Astrophysics

First spin sidebands of J1912−4410 fail a sinusoidal phase constraint in a finite linear model of TESS Sector 104

We test one constant-amplitude spin sinusoid with one sinusoidal orbital phase change in the known white dwarf pulsar J1912−4410. We fit 16,008 public TESS Sector 104 samples with a finite Fourier model and a linear 120-second response. The Bessel expansion gives an exact constraint on the first two sidebands, without a small phase-change approximation. The measured complex constraint has magnitude 0.289, with a 95% one-day sign interval of 0.212 to 0.370. We fit the constrained flux model and fit it again in each noise trial. No one-day trial out of 9,999 reaches the observed increase in residual sum of squares. With two-day groups, 8 of all 4,096 sign patterns reach it. These are approximate fitted-null checks that assume independent group scores with equal probabilities for opposite signs. Trends, wider Fourier models, weights, corrected flux, and small apertures give similar departures. The second time half gives weaker evidence. We also derive a geometric light-travel bound for any Kepler ellipse with total mass at most 3 solar masses. Its sideband ratio limit is 0.0846, below the measured 0.3533. Earlier work already rejected travel time for older pulse shifts. This contribution adds the phase-model test, the general bound, and reproducible code. Arbitrary phase functions and nonlinear TESS frame rejection remain outside the tested model. Exact input data, provenance, trials, figures, and reproduction instructions are included.

J1912-4410 · white dwarf pulsar · TESS Sector 104 · phase modulation · orbital sidebands · light travel time · constrained Fourier fit · public data

Admitted 3 citing publications

References

9
  1. usesA joint Fourier fit with a linear 120-second response gives a beat-to-spin amplitude ratio of 0.35 for J1912−4410 in TESS Sector 104 sci:sha256:e6d4b5b9b545c71f306f8098b437173f9028c71a7709fc5b4ea84803f05e046d

    We reuse its verified exact TESS inputs, archive provenance, selected clock, and model specification. We reproduce its main coefficients with new code. We extend its amplitude-envelope test to one sinusoidal phase change. Its unequal sidebands already motivate this follow-up.

  2. usesdoi:10.1038/s41550-023-01995-x

    We use the orbital period and source identity. This discovery paper already excluded orbital light-travel time for earlier optical pulse shifts. Our work gives a general bound and a dated comparison with different data.

  3. doi:10.1093/mnras/stad3442

    This study detected the ultraviolet beat and showed that pulse phase depends on wavelength and data set. It limits cross-band timing claims.

  4. usesdoi:10.22323/1.514.0061

    We use its explicit Figure 2 radio spin frequency, as selected by the source SCI study. The printed period values differ slightly from that frequency.

  5. doi:10.1111/j.1365-2966.2012.20654.x

    This prior method uses orbital frequency modulation and Fourier sidebands to study binary pulsating stars. The Fourier and Bessel identities are established.

  6. doi:10.48550/arXiv.2507.15352

    This prior radio model includes a more complex emission geometry for J1912−44. Our simple sinusoidal phase test does not test that geometry.

  7. doi:10.48550/arXiv.2609.27543

    We searched this recent review for the state of white dwarf pulsar observations and interpretation.

  8. usesdoi:10.17909/t9-nmc8-f686

    We use the exact public two-minute TESS light curve of TIC 61510984 in Sector 104.

  9. usesdoi:10.17909/t9-yk4w-zc73

    We use the matching target pixel file for two small-aperture checks.

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