| We have started a major observational campaign to force a breakthrough in the research of fundamental physics using neutron stars and black holes by exploiting the world-class X-ray and optical observatories to their extreme capabilities. The key measurements will allow model-independent mass measurements of black hole and neutron star compact objects. The main scientific questions that can be tackled with such measurements are: -What is the black hole mass distribution? This can be used to constrain supernova and binary evolution models. Two important questions in this respect are what is the lowest mass of a stellar mass black hole and what is the highest mass? -Can we characterise the behaviour of matter at the densities and pressures encountered in the core of neutron stars? We cannot create or study those circumstances in laboratories on Earth. The mass of a neutron star is the parameter that will allow us to discriminate between the various models if the neutron star is significantly more massive than at formation. To facilitate the breakthrough we will capitalise on the arrival of the first second-generation instrument at the Very Large Telescope of the European Southern Observatory (ESO) called X-shooter. The instrument, with a significant Dutch contribution, provides an important improved sensitivity and resolution with respect to existing spectrographs on European as well as American telescopes. We will use the currently operational X-ray satellites, XMM-Newton and Chandra in conjunction with the optical telescope data to measure neutron star and black hole masses. |
