Extragalactic TeV gamma ray sources carry potentially very useful information for probing basic physics. The goal of this project is to bring together all necessary ingredients to exploit these data the best. The axes of the proposal are the study of the cosmological standard model, the search for new light bosons (axion-like particles, ALPs) and the search for Lorentz invariance breaking. In all cases, specific properties in the sources energy spectra are sought. TeV photons allow probing the extragalactic background light, which they interact with. This is how the cosmological model will be tested (metric, cosmological parameters). In case of an absence of detection of exotic effects (axions, Lorentz invariance breakdown), it will be possible to constraint particles physics models predicting ALPs and to set lower limits on the energy scale up to which Lorentz invariance holds. The IRFU team is traditionally involved in the search for new physics, in particular the search for non-baryonic dark matter. This project aims at extending the activity of the group to other fundamental physics domains within astroparticle physics. We propose to join forces with the Polish group of R. Moderski, who is specialized in the modeling of conventional TeV gamma ray emissions. His PhD student A. Barnacka is already in joint supervision PhD thesis together with the IRFU group in Saclay. The Warsaw Nicolaus Copernicus Center appears as associated lab, which receives no funding from the ANR. Predictions for the intrinsic spectrum of the source and the magnetic field configuration will be used to make theoretical predictions. Those will be tested with the HESS, Fermi and HESS II data and then used to estimate the sensitivity of future gamma ray observatories to these effects. A key point of this project is that it aggregates different types of knowledge that can be used for other analyses as by-products. It is the merging of two teams specialized respectively in the modeling of TeV emissions and in the search for new physics with gamma-ray astronomy that is the important point here. So in a second phase, we propose to study other subjects, for example constraining the properties of the propagation of TeV photons in the intergalactic medium (large-scale relic magnetic fields, ultra-high energy cosmic rays, gravitational lensing, etc). Other even more challenging subjects may be studied if the previous analyses are successful, such as the use of gamma ray bursts. It is foreseen to organize two workshops dedicated to the search for new phenomena with TeV sources. This project enlarges the topics in which the IRFU team is traditionally involved. The proposal is held by a team of young physicists whose collaboration will naturally sustain when the project ends thanks to the starting of next generation observatories and the wealth of subjects raised. ANR funding will allow hiring a 3 year post-doc and increase significantly the work capacity of the team. The funding will also cover travels and the organization of dedicated workshops.