X- and Gamma-ray astrophysics in the era of Multi-messenger astronomy

Abstract

Multi-messenger astronomy is becoming a major avenue to explore the Universe. Several well known astrophysical sources are also expected to emit other 'messenger' than photons: namely cosmic rays, gravitational waves and neutrinos. These additional messengers bring complementary pieces of information to the ones carried by electromagnetic radiation and concur to draw a complete phenomenological picture of several astrophysical events as well as to measure key cosmological parameters. Indeed, it is widely believed in the astronomical community that several aspects of fundamental physics and cosmology will be unveiled only within the framework of multi-messenger astronomy. The most recent breakthrough discoveries of a gravitational wave source associated with a short gamma-ray burst, and of a neutrino event found to be spatially consistent with a flaring blazar, have already shown the key role that high-energy sources will play in multi-messenger observations. The first part of this chapter provides a description of the main properties of gamma-ray bursts, blazars, and other high-energy sources from which we expect to detect gravitational waves and/or neutrinos in the next years, and the achievements that will be reached from multi-messenger observations. The second part of the chapter is focused on the major facilities that are playing and that will play a crucial role in multi-messenger observational campaigns. More specifically, we provide an overview of current and next generation ground-based gravitational wave interferometers and neutrino telescopes, as well as the major X-ray and gamma-ray observatories that will be crucial for multi-messenger observations in the coming years.