The detection and analysis of the gravitational radiation emitted by diverse astrophysical and cosmological sources promises to open a completely new window to the exploration of the Universe. The developments towards Gravitational Wave Astronomy are currently following different paths. On one hand, second-generation ground-based interferometric detectors [LIGO (USA), VIRGO (Italy-EGO), and KAGRA (Japan)] in the high-frequency band (1 − 104 Hz) are going to start operations during this decade, and are expected to provide the first detections. There are also plans for a third-generation observatory, the Einstein Telescope, an European project currently funded by the ASPERA network. These detectors will observe general relativistic phenomena such as the coalescence and merger of stellar compact binaries containing neutron stars and black holes. They are also sensitive to gravitational emissions from core-collapse supernovae and to early-universe backgrounds. On the other hand, the design of space-based detectors that will cover the low-frequency band (10−5 − 1 Hz) has a long history, and in particular the European project eLISA, which aims at becoming an European Space Agency Large mission, will search for supermassive black hole binary coalescence, inspirals of stellar compact objects into supermassive black holes, thousands of galactic binaries, and stochastic backgrounds of gravitational waves. Finally, we have the Pulsar Timing Arrays (PTAs), which look at variations in the arrival times of radio emissions from millisecond pulsars due to the passage of gravitational waves. There are three PTAs [NANOGrav (USA), EPTA (Europe), and PPTA (Australia)] operating radio-telescopes that monitor sets of millisecond pulsars to detect the presence of gravitational waves in the very low frequency band (10−9 − 10−7 Hz). These arrays, organized in the International PTA (IPTA) consortium, are expected to make the first detections on a timescale of decades, and are currently providing unique constraints on gravitational waves from inspirals of supermassive black holes, cosmic strings, and other sources. There is therefore a strong motivation to study the astrophysical mechanisms that create the different gravitational-wave sources (to understand their distribution and event rates) and also the physical connection between these sources and other astrophysical and cosmological processes. For instance, observations by large telescopes for electromagnetic transient signals together with gravitational-wave observations will provide rich information for high-energy phenomena such as gamma-ray bursts. Moreover, the detection of supermassive black hole mergers can help us understand the mechanisms of galaxy formation, explore the structure of black holes and test General Relativity and other theories of gravity. Taking into account the technological developments in gravitational-wave detectors, it is an excellent time to organize a workshop to discuss the state of the art of the main astrophysics associated with the sources of gravitational waves and the hidden universe that can be unveiled through these observations. At the same time, we will aim to produce a reference book on the topic, going beyond normal proceedings, which could be an useful entrance to the field and provide a wide panorama of the astrophysics of gravitational waves. The book will be edited by the organizers, and contributed by participants, especially invited speakers. Following tradition, the SOC will grant the Sant Cugat Forum of Astrophysics Award to Young Scientists.
All of these issues, as well as the logistics of the workshop in the framework of the Sant Cugat Forum of Astophysics are detailed in this web.