SÉMINAIRE DU GRECO
"Recent progress in the theory of time transfer functions in Schwarzschild-like spacetimes: A unified description of Shapiro and lensing effects." |
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Pierre Teyssandier |
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Determining the travel time of a light ray as a function of the positions of the emitter and the receiver -- a so-called time transfer function -- is of crucial interest for modeling the geometric optical effects in metric theories of gravity. We present a complete solution to this problem within the linearized, weak-field approximation of a Schwarzschild-like metric. We prove in this context the existence of two time transfer functions, and we determine these functions in a closed-form. A discussion shows that there exist two main regimes, one of them occurring in gravitational lensing, the other one yielding the well-known Shapiro time delay completed by a series of so-called enhanced terms that must be taken into account for light rays grazing the Sun or giant planets. Thus we obtain a unified description of configurations which were treated until now in completely different ways. |
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lundi 16 janvier 2017 - 11:00 Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris |
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