Planetary ephemerides are a very powerful tool to constrain deviations from the theory of General Relativity using orbital dynamics. The effective field theory framework called the Standard-Model Extension (SME) has been developed in order to systematically parametrize hypothetical violations of Lorentz symmetry (in the Standard Model and in the gravitational sector). In this communication, we use the latest determinations of the supplementary advances of the perihelia and of the nodes obtained by planetary ephemerides analysis to constrain SME coefficients from the pure gravity sector and also from gravity-matter couplings. Our results do not show any deviation from GR and they improve current constraints. Moreover, combinations with existing constraints from Lunar Laser Ranging and from atom interferometry gravimetry allow us to disentangle contributions from the pure gravity sector from the gravity-matter couplings.

Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both general relativity and the standard model of particle physics called the standard-model extension (SME). We present new constraints on pure gravity SME coefficients obtained by analyzing lunar laser ranging (LLR) observations. We use a new numerical lunar ephemeris computed in the SME framework and we perform a LLR data analysis using a set of 20721 normal points covering the period of August, 1969 to December, 2013. We emphasize that linear combination of SME coefficients to which LLR data are sensitive and not the same as those fitted in previous postfit residuals analysis using LLR observations and based on theoretical grounds. We found no evidence for Lorentz violation at the level of 10 We improve previous constraints on SME coefficient by a factor up to 5 and 800 compared to postfit residuals analysis of respectively binary pulsars and LLR observations.

Context. In the dense and cold prestellar cores, many species freeze out onto grains to form ices. The most conspicuous case is that of CO itself. Only upper limits of this depletion amplitude can be estimated because the CO emission from the external undepleted layers mask the emission of CO left inside the depleted region. The finite signal-to-noise ratio of the observations is another limitation. However, depletion and even more desorption mechanisms are not well-known and need observational constraints, i.e., depletion profiles. Aims. We describe a method for retrieving the CO and N 2 abundance profiles inside prestellar cores, which is mostly free of initial conditions. Methods. DCO + is a daughter molecule of CO, which appears inside depleted prestellar cores. The main deuteration partners are the H + 3 isotopologues. By determining the abundance of these isotopologues via N 2 D + , N 2 H + , and ortho-H 2 D + observations and a chemical model, we can uniquely constrain the CO abundance, the only free parameter left, to fit the observed DCO + abundance. The N 2 abundance is also determined in the same manner once CO is known. DCO + -H 2 collisional rates including the hyperfine structure were computed in order to determine the DCO + abundance. Results. To illustrate the method, we apply it to the main L183 prestellar core and find that the CO abundance profile varies from ≥2.4 × 10 −5 at the core edge to ≤6.6 × 10 −8 at the center. This represents a relative decrease in abundance by ≥360, and by ≥2000 compared to the standard undepleted CO abundance (1-2 × 10 −4 ). Comparatively, N 2 abundance decreases much less, from ≤3.7 × 10 −7 down to ∼2.9 × 10 −8 , in contrast to the similar binding properties of the two species. Because the N 2 abundance is lower than its steady state value at the edge, while CO is close to its own, a possible explanation is that N 2 is still in its production phase in competition with depletion. Conclusions. The method allows the CO and N 2 abundance profiles to be retrieved in the depleted zone both without needing extremely high signal-to-noise observations and free of masking effects by extended emission from the cloud envelope. The main uncertainties are linked to the N 2 H + collisional rates and somewhat to the H + 3 isotopologue rates, both collisional and chemical, but hardly to the initial conditions of the model. This method opens up possibilities of testing depletion and desorption mechanisms in prestellar cores and time evolution models, and of addressing the debated CO/N 2 depletion controversy.

Lorentz symmetry is one of the pillars of both General Relativity and the Standard Model of particle physics. Motivated by ideas about quantum gravity, unification theories and violations of CPT symmetry, a significant effort has been put the last decades into testing Lorentz symmetry. This review focuses on Lorentz symmetry tests performed in the gravitational sector. We briefly review the basics of the pure gravitational sector of the Standard-Model Extension (SME) framework, a formalism developed in order to systematically parametrize hypothetical violations of the Lorentz invariance. Furthermore, we discuss the latest constraints obtained within this formalism including analyses of the following measurements: atomic gravimetry, Lunar Laser Ranging, Very Long Baseline Interferometry, planetary ephemerides, Gravity Probe B, binary pulsars, high energy cosmic rays, . . . In addition, we propose a combined analysis of all these results. We also discuss possible improvements on current analyses and present some sensitivity analyses for future observations.

The standard-model extension (SME) is an effective field theory framework aiming at parametrizing any violation to the Lorentz symmetry (LS) in all sectors of physics. In this Letter, we report the first direct experimental measurement of SME coefficients performed simultaneously within two sectors of the SME framework using lunar laser ranging observations. We consider the pure gravitational sector and the classical point-mass limit in the matter sector of the minimal SME. We report no deviation from general relativity and put new realistic stringent constraints on LS violations improving up to 3 orders of magnitude previous estimations.

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Context. Ground-based astro-geodetic observations and atmospheric occultations, are two examples of observational techniques requiring a scrutiny analysis of atmospheric refraction. In both cases, the measured changes in observables (range, Doppler shift, or signal attenuation) are geometrically related to changes in the photon path and the light time of the received electromagnetic signal. In the context of geometrical optics, the change in the physical properties of the signal are related to the refractive profile of the crossed medium. Therefore, having a clear knowledge of how the refractivity governs the photon path and the light time evolution is of prime importance to clearly understand observational features. Analytical studies usually focused on spherically symmetric atmospheres and only few aimed at exploring the effect of the non-spherical symmetry on the observables.Aims. In this paper, we analytically perform the integration of the photon path and the light time of rays traveling across a planetary atmosphere. We do not restrict our attention to spherically symmetric atmospheres and introduce a comprehensive mathematical framework which allows to handle any kind of analytical studies in the context of geometrical optics.Methods. Assuming that the index of refraction of the medium is a linear function of the Newtonian potential, we derive an exact solution to the equations of geometrical optics. The solution's arbitrary constants of integration are parametrized by the refractive response of the medium to the gravitational potential, and by the first integrals of the problem. Varying the constants, we are able to reformulate the equation of geometrical optics into a new set of osculating equations describing the constants' evolution for any arbitrary changes in the index of refraction profile.Results. The osculating equations are identical to the equation of geometrical optics, however, they offer a comprehensive framework to handle analytical studies which aim at exploring non-radial dependencies in the refractive profile. To highlight the capabilities of this new formalism, we carry out five realistic applications for which we derive analytical solutions. The accuracy of the method of integration is assessed by comparing our results to a numerical integration of the equations of geometrical optics in the presence of a quadrupolar moment J 2 . This shows that the analytical solution leads to the determination of the light time and the refractive bending with relative errors at the level of one part in 10 8 and one part in 10 5 , for typical values of the refractivity and the J 2 parameter at levels of 10 −4 and 10 −2 , respectively. * adrien.bourgoin@unibo.it arXiv:1901.08461v1 [physics.class-ph]

Based on a fully passive space segment, the lunar laser ranging experiment is the last of the Apollo Lunar Surface Experiments Package to operate. Observations from the Grasse lunar laser ranging station have been made on a daily basis since the first echoes obtained in 1981. In this paper, first, we review the principle and the technical aspects of lunar laser ranging. We then give a brief summary of the progress made at the Grasse laser ranging facility (Observatoire de la Côte d'Azur, Calern Plateau on the French Riviera) since the first echoes. The current performance, driven by the use of an infrared wavelength laser, is presented in the last section for the year 2018.