There is an impressive income of observational data for compact objects, which include black holes, neutron stars, white dwarfs. These compact objects are generated through the accretion of matter. Recently, observations of LIGO/Virgo proved the existence of binary black holes mergers through detection of gravitational waves, and additionally the Event Horizon Telescope revealed the existence of supermassive black holes in centre of galaxy M87 and Milky Way. Future observational data,  will permit to probe additional gravitational parameters, eventually checking the validity of no-hair theorems, star trajectories beyond precession, novel observations of exceptional objects, including binary pulsars in a strong gravity field. One could possibly entertain the discovery of novel compact objects theoretically disfavoured from GR such as hairy black holes or wormholes, for example distinguishing a wormhole throat versus an event horizon. A fruitful way of  testing the behaviour of compact objects is to explore the features of modified gravity theories. 

The purpose of this workshop is to discuss the generation of compact objects by the interaction of matter to black holes in general modified gravity theories like scalar-tensor theories, high curvature theories and theories with high derivatives. 

The Workshop will take place in a Conference Room in the Building Averof of the School of Architecture in the Central Campus of National Technical University of Athens which is located at Patission Street in central Athens (see the map). Note that the entrance to the NTUA Campus is from Stournari Street. The Workshop is sponsored by the National Technical University of Athens, the University of Tuebingen, the University of Paris-Saclay and COST (European Cooperation in Science and Technology).