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In the realm of the Hubble tension-a review of solutions
Riess, Adam G.; Di Valentino, Eleonora; Melchiorri, Alessandro +6 more
The simplest ΛCDM model provides a good fit to a large span of cosmological data but harbors large areas of phenomenology and ignorance. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the model have emerged. The most statistically significant tension is the 4σ to 6σ disagreem…
Light propagation in 2PN approximation in the field of one moving monopole II. Boundary value problem
Zschocke, Sven
In this investigation the boundary value problem of light propagation in the gravitational field of one arbitrarily moving body with monopole structure is considered in the second post-Newtonian approximation. The solution of the boundary value problem comprises a set of altogether three transformations: , , and . Analytical solutions of these tra…
Gaia-like astrometry and gravitational waves
Klioner, Sergei A.
This paper discusses the effects of gravitational waves on high-accuracy astrometric observations such as those delivered by Gaia. Depending on the frequency of gravitational waves, two regimes for the influence of gravitational waves on astrometric data are identified: the regime when the effects of gravitational waves directly influence the deri…
Light propagation in 2PN approximation in the field of one moving monopole I. Initial value problem
Zschocke, Sven
In this investigation the light propagation in the gravitational field of one arbitrarily moving body with monopole structure is considered in the second post-Newtonian approximation. It is found that the light trajectory depends on the acceleration of the body. Some of these acceleration terms are important in order to get well-defined logarithmi…
The ray tracing analytical solution within the RAMOD framework. The case of a Gaia-like observer
Lattanzi, M. G.; Crosta, M.; Vecchiato, A. +1 more
This paper presents the analytical solution of the inverse ray tracing problem for photons emitted by a star and collected by an observer located in the gravitational field of the Solar System. This solution has been conceived to suit the accuracy achievable by the ESA Gaia satellite (launched on 19 December 2013) consistently with the measurement…
Time transfer functions as a way to validate light propagation solutions for space astrometry
Bertone, Stefano; Crosta, Mariateresa; Vecchiato, Alberto +3 more
Given the extreme accuracy of modern space astrometry, a precise relativistic modeling of observations is required. Concerning light propagation, the standard procedure is the solution of the null-geodesic equations. However, another approach based on the time transfer functions (TTF) has demonstrated its capability to give access to key quantitie…