Windows on the Universe: the Era of Multi-Messenger Astrophysics

The Universe is the ultimate laboratory, and we can now probe it as never before through several powerful and diverse windows &ndash; electromagnetic waves, high-energy particles, and gravitational waves. Each of these windows provides a different view. Together they reveal a detailed picture of the Universe that will allow us to study matter, energy, and the cosmos in fundamentally new ways. The &ldquo;Windows on the Universe&rdquo; Multi-Messenger Astrophysics (WoU-MMA) program identifies three categories of messengers - electromagnetic waves, high-energy particles including neutrinos and cosmic rays, and gravitational waves. The goals of WoU-MMA are to build the capabilities and accelerate the synergy between observations and theory to realize integrated, multi-messenger astrophysical explorations of the Universe. The WoU-MMA program welcomes proposals in any area of research supported through the participating divisions that address at least one of the following criteria: <ul> <li>Coordination: Activities to coordinate observations involving more than one messenger.</li> <li>Observations: Observations of astrophysical objects or phenomena that are potentially sources of more than one messenger.</li> <li>Interpretation: Theory, experiment, simulations and other activities to understand or interpret observations of astrophysical objects that are sources of more than onemessenger.</li> </ul> Competitive proposals will accelerate the progress in multi-messenger astrophysics and advance the community activities that have been developed during the initial five-year period of the WoU-MMA program. These build on observational and analysis capabilities at the intersection of the explorations enabled by each of the three windows. Efforts to integrate research communities to develop full interoperability between the three windows, and to develop a skilled new workforce in this field, are also encouraged. Proposals should be submitted to the relevant programs listed below...