arXiv subjects

Andreas Rathke

Publications and source records attributed to Andreas Rathke.

9 recordsLinked to original sources

arXiv2006

Options for a nondedicated mission to test the Pioneer anomaly

The Doppler-tracking data of the Pioneer 10 and 11 spacecraft show an unmodelled constant acceleration in the direction of the inner Solar System. Serious efforts have been undertaken to find a conventional explanation for this effect, all without success at the time of writing. Hence the effect, commonly dubbed the Pioneer anomaly, is attracting considerable attention. Unfortunately, no other space mission has reached the long-term navigation accuracy to yield an independent test of the effect. To fill this gap we discuss strategies for an experimental verification of the anomaly via an upcoming space mission. Emphasis is put on two plausible scenarios: nondedicated concepts employing either a planetary exploration mission to the outer Solar System or a piggybacked micro-spacecraft to be launched from a mother spacecraft travelling to Saturn or Jupiter. The study analyses the impact of a Pioneer anomaly test on the system and trajectory design for these two paradigms. It is found that both paradigms are capable of verifying the Pioneer anomaly and determine its magnitude at 10% level. Moreover the concepts can discriminate between the most plausible classes of models of the anomaly, a central force, a blueshift of the radio signal and a drag-like force. The necessary adaptions of the system and mission design do not impair the planetary exploration goals of the missions.

astro-ph↗

arXiv2005

Pioneer anomaly: What can we learn from LISA?

The Doppler tracking data from two deep-space spacecraft, Pioneer 10 and 11, show an anomalous blueshift, which has been dubbed the "Pioneer anomaly". The effect is most commonly interpreted as a real deceleration of the spacecraft - an interpretation that faces serious challenges from planetary ephemerides. The Pioneer anomaly could as well indicate an unknown effect on the radio signal itself. Several authors have made suggestions how such a blueshift could be related to cosmology. We consider this interpretation of the Pioneer anomaly and study the impact of an anomalous blueshift on the Laser Interferometer Space Antenna (LISA), a planned joint ESA-NASA mission aiming at the detection of gravitational waves. The relative frequency shift (proportional to the light travel time) for the LISA arm length is estimated to 10E-16, which is much bigger than the expected amplitude of gravitational waves. The anomalous blueshift enters the LISA signal in two ways, as a small term folded with the gravitational wave signal, and as larger term at low frequencies. A detail analysis shows that both contributions remain undetectable and do not impair the gravitational-wave detection. This suggests that the Pioneer anomaly will have to be tested in the outer Solar system regardless if the effect is caused by an anomalous blueshift or by a real force.

gr-qc↗

arXiv2005

A critical analysis of the hydrino model

Recently, spectroscopic and calorimetric observations of hydrogen plasmas and chemical reactions with them have been interpreted as evidence for the existence of electronic states of the hydrogen atom with a binding energy of more than 13.6 eV. The theoretical basis for such states, that have been dubbed hydrinos, is investigated. We discuss both, the novel deterministic model of the hydrogen atom, in which the existence of hydrinos was predicted, and standard quantum mechanics. Severe inconsistencies in the deterministic model are pointed out and the incompatibility of hydrino states with quantum mechanics is reviewed.

quant-ph↗

arXiv2004

Testing for the Pioneer anomaly on a Pluto exploration mission

The Doppler-tracking data of the Pioneer 10 and 11 spacecraft show an unmodelled constant acceleration in the direction of the inner Solar System. An overview of the phenomenon, commonly dubbed the Pioneer anomaly, is given and the possibility for an experimental test of the anomaly as a secondary goal of an upcoming space mission is discussed using a putative Pluto orbiter probe as a paradigm.

astro-ph↗

arXiv2004

Constraining a possible dependence of Newton's constant on the Earth's magnetic field

Some time ago Mbelek and Lachieze-Rey proposed that the discrepancy between the results of the various measurements of Newton's constant could be explained by introducing a gravielectric coupling between the Earth's gravitational and magnetic fields mediated by two scalar fields. A critical assessment of this model is performed. By calculating the static field configuration of the relevant scalar around a nucleus in the linearised theory and then folding this result with the mass density of the nucleus its effective gravitational mass is determined. Considering test bodies of different materials one finds violations of the weak equivalence principle for torsion-balance experiments which are four orders of magnitude beyond the current experimental limit, thus rendering the model non-viable. The method presented can be applied to generic theories with gravielectric coupling and seems to rule out in general the explanation of the discrepant measurements of Newton's constant by such couplings.

gr-qc↗

arXiv2003

Will LIGO see RIGO's? - Radion-induced graviton oscillations in the two-brane world

One of the most interesting features of braneworld models is the existence of massive gravitational modes in addition to the usual massless one. Mixing of the modes which depends nontrivially on the inter-brane distance can be interpreted as radion-induced gravitational-wave oscillations, a classical analogy to meson and neutrino oscillations. We show that these oscillations arising in M-theory inspired two-brane setups could lead to effects detectable by gravitational-wave interferometers.

astro-ph↗

arXiv2003

Graviton oscillations in the two-brane world

We study the braneworld effective action in the two-brane Randall-Sundrum model. In the framework of this essentially-nonlocal action we reveal the origin of an infinite sequence of gravitational wave modes -- the usual massless one as well as the tower of Kaluza-Klein massive ones. Mixing of the modes, which parametrically depends on the background value of the modulus of the extra dimension, can be interpreted as radion-induced gravitational-wave oscillations, a classical analogue to meson and neutrino oscillations. We show that these oscillations arising in M-theory-inspired braneworld setups could lead to effects detectable by gravitational-wave interferometers.

hep-th↗

arXiv2003

Radion-induced gravitational wave oscillations and their phenomenology

We discuss the theory and phenomenology of the interplay between the massless graviton and its massive Kaluza-Klein modes in the Randall-Sundrum two-brane model. The equations of motion of the transverse traceless degrees of freedom are derived by means of a Green function approach as well as from an effective nonlocal action. The second procedure clarifies the extraction of the particle content from the nonlocal action and the issue of its diagonalization. The situation discussed is generic for the treatment of two-brane models if the on-brane fields are used as the dynamical degrees of freedom. The mixing of the effective graviton modes of the localized action can be interpreted as radion-induced gravitational-wave oscillations, a classical analogy to meson and neutrino oscillations. We show that these oscillations arising in M-theory-motivated braneworld setups could lead to effects detectable by gravitational-wave interferometers. The implications of this effect for models with ultra-light gravitons are discussed.

hep-th↗

arXiv2002

Nonlocal braneworld action: an alternative to Kaluza-Klein description

We construct the nonlocal braneworld action in the two-brane Randall-Sundrum model in a holographic setup alternative to Kaluza-Klein description: the action is written as a functional of the two metric and radion fields on the branes. This action effectively describes the dynamics of the gravitational field both on the branes and in the bulk in terms of the brane geometries directly accessible for observations. Its nonlocal form factors incorporate the cumulative effect of the bulk Kaluza-Klein modes. We also consider the reduced version of this action obtained by integrating out the fields on the negative-tension brane invisible from the viewpoint of the Planckian brane observer. This effective action features a nontrivial transition (AdS flow) between the local and nonlocal phases of the theory associated with the limits of small and large interbrane separation. Our results confirm a recently proposed braneworld scenario with diverging (repulsive) branes and suggest possible new implications of this phase transition in brane cosmology.

hep-th↗