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astro-ph.EP · Earth and Planetary Astrophysicsastro-ph.IM · Instrumentation and Methods for Astrophysicsastro-ph.HE · High Energy Astrophysical Phenomena

Parallax fits reduce the minimum retained information fraction by factors of 144 to 230 for 365.25-day e=0.1 orbits in seven NANOGrav models with fixed noise

We tested how astrometry fits affect eccentric annual planet signals in seven public NANOGrav timing models. The calculation uses 82,598 pulse times of arrival from release 2.1.0. The period is 365.25 TDB days. Noise values and timing derivatives stay fixed. The reference fixes both position coordinates, both proper-motion components, and parallax, and fits every other delivered free timing term. At eccentricity e=0.1, the minimum retained information fraction ranges from 3.17e-6 to 4.60e-5 across targets. Each minimum is over orbital phase and orientation. Fixing parallax raises these minima by factors of 144 to 230. For the same weak orbit shapes, the increase is 174 to 334. A diagonal-noise control keeps the effect. An ideal model with uniform observations gives leading minimum fractions e^2/4 with parallax fixed and 9e^4/64 with parallax free. Parallax can remove the second orbital harmonic. The general annual loss is known. This work adds measured eccentric phase maps, parallax controls, direct Kepler witnesses, and portable information kernels for specified public data. We checked all 560 retained extrema by direct Kepler calculation, doubled the phase grid, and checked covariance, rank, and independent least squares. These are numerical extrema in a linear model. We did not search residuals, detect a planet, or set planet mass limits. The package preserves code, source files and hashes, data provenance, tables, figures, and offline reproduction instructions.

pulsar timing · eccentric orbits · annual planet signals · parallax · Fisher information · NANOGrav · harmonic kernels · reproducible methods

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References

8
  1. usesFree sky positions retain less than 0.05% of 365.25-day signal information in seven fixed-noise NANOGrav models sci:sha256:80e8d7d7a024f51e5aaa1b1c455f1a4051c86897f03e78e8ec4fc4afdad57142

    We reuse its seven compact timing inputs, original selected source files, preparation code, and whitening method. We reproduce its circular values and extend the calculation to eccentric annual orbits with a different reference.

  2. usesdoi:10.5281/zenodo.16051178

    This is the exact NANOGrav 15-year data release 2.1.0 used by the inherited timing arrays. Selected original timing and clock files are preserved.

  3. usesdoi:10.3847/2041-8213/acda9a

    This paper describes the source observations and timing analysis.

  4. supportsdoi:10.3847/2041-8213/ab8121

    Section 3 describes the known annual loss from position and proper-motion fits and the second-harmonic loss from parallax.

  5. supportsdoi:10.1088/0004-637X/777/2/104

    Section 2 gives the astrometry harmonics and explains signal absorption. The general benefit of independent astrometry is prior work.

  6. doi:10.1093/mnras/stac593

    This earlier search models circular and eccentric pulsar planet signals with timing and noise terms. It treats the annual period interval separately.

  7. doi:10.48550/arXiv.2408.09795

    This EPTA study searches eccentric periodic signals with joint timing and noise modeling and discusses annual sensitivity loss. We read arXiv version 1.

  8. usesdoi:10.3847/1538-4357/abe62f

    PINT supplies the inherited timing derivatives, barycentric times, and noise specification. The source arrays used PINT 1.1.8.

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