recent stuff on Pioneer anomaly

[Martin]

If anyone has a subscription they might want to check this and see what it says. i dont know if the article is any good.

http://www.newscientistspace.com/article/mg19025541.800.html

 

there is what looks like some new development here including a Moffat paper just this past week

the impressive thing is the first paper here is NOT ABOUT PIONEER BUT ABOUT GALAXY ROTATION CURVES,

 

Moffat started by inventing a modification of Gen Rel that would GET RID OF DARK MATTER as something needed to hold galaxys from flying apart from the observed spin. He made gravity a little stronger way out where it is usually very weak (like out at the edges) and then it fit the observed rotation speeds very well

 

http://arxiv.org/abs/astro-ph/0412195

Gravitational Theory, Galaxy Rotation Curves and Cosmology without Dark Matter

J. W. Moffat

33 pages, 20 figures, 1 table. To be published in Journal of Cosmology and Astroparticle Physics (JCAP)

JCAP 0505 (2005) 003

"Einstein gravity coupled to a massive skew symmetric field F_{\mu\nu\lambda} leads to an acceleration law that modifies the Newtonian law of attraction between particles. We use a framework of non-perturbative renormalization group equations as well as observational input to characterize special renormalization group trajectories to allow for the running of the effective gravitational coupling G and the coupling of the skew field to matter. The latter lead to an increase of Newton's constant at large galactic and cosmological distances. For weak fields a fit to the flat rotation curves of galaxies is obtained in terms of the mass (mass-to-light ratio M/L) of galaxies. The fits assume that the galaxies are not dominated by exotic dark matter and that the effective gravitational constant G runs with distance scale. The equations of motion for test particles yield predictions for the solar system and the binary pulsar PSR 1913+16 that agree with the observations. The gravitational lensing of clusters of galaxies can be explained without exotic dark matter. An FLRW cosmological model with an effective G=G(t) running with time can lead to consistent fits to cosmological data without assuming the existence of exotic cold dark matter."

 

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then the surprise is, that this model can be applied to the solar system and can ALSO fit the observed Pioneer behavior which indicates a tiny bit stronger way out at the edges.

 

http://arxiv.org/gr-qc/0511026

Gravitational solution to the Pioneer 10/11 anomaly

J. R. Brownstein, J. W. Moffat

12 pages, 3 figures, 2 tables.

Class. Quantum Grav. 23 (2006) 3427-3436

"A fully relativistic modified gravitational theory including a fifth force skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The theory allows for a variation with distance scales of the gravitational constant G, the fifth force skew symmetric field coupling strength omega and the mass of the skew symmetric field mu=1/lambda. A fit to the available anomalous acceleration data for the Pioneer 10/11 spacecraft is obtained for a phenomenological representation of the "running" constants and values of the associated parameters are shown to exist that are consistent with fifth force experimental bounds. The fit to the acceleration data is consistent with all current satellite, laser ranging and observations for the inner planets."

 

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and then a further gratifying development as of this week,

Moffat figured out a way that you could TEST HIS THEORY AND SEE IF IT IS WRONG without having to send another Pioneer-like probe way far out but just by making some extra accurate measurements involving EXISTING PROBES GOING ABOUT THEIR BUSINESS.

http://arxiv.org/abs/gr-qc/0605141

Time Delay Predictions in a Modified Gravity Theory

J. W. Moffat

5 pages

"The time delay effect for planets and spacecraft is obtained from a fully relativistic modified gravity theory including a fifth force skew symmetric field by fitting to the Pioneer 10/11 anomalous acceleration data. A possible detection of the predicted time delay corrections to general relativity for the outer planets and future spacecraft missions is considered. The time delay correction to GR predicted by the modified gravity is consistent with the observational limit of the Doppler tracking measurement reported by the Cassini spacecraft on its way to Saturn, and the correction increases to a value that could be measured for a spacecraft approaching Neptune and Pluto."

 

my attention was focused on this by Bee's VOYAGER thread where question came up about the Pioneer anomaly. IMO this Moffat thing has the potential of becoming a story.

 

another New Scientist article, older but free (so you dont need a subscription) is here

http://www.newscientistspace.com/article/dn8631

 

still more stuff

http://arxiv.org/abs/gr-qc/0512121

The Study of the Pioneer Anomaly: New Data and Objectives for New Investigation

Slava G. Turyshev, Viktor T. Toth, Larry R. Kellogg, Eunice. L. Lau, Kyong J. Lee

Comments: 43 pages, 40 figures, 3 tables, minor changes before publication

Journal-ref: Int.J.Mod.Phys. D15 (2006) 1-56

 

and more stuff

http://arxiv.org/abs/gr-qc/0603016

The Pioneer Anomaly: Seeking an explanation in newly recovered data

Viktor T Toth, Slava G Turyshev

22 pages, 21 figures, 2 tables